Assured Guaranty (AGO) 10-K 26 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 23, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Entity Registrant Name	ASSURED GUARANTY LTD
Entity Central Index Key	1273813
Document Type	10-K
Document Period End Date	31-Dec-14
Amendment Flag	FALSE
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$4,209,699,122
Entity Common Stock, Shares Outstanding		155,444,695
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Investment portfolio:
Fixed-maturity securities, available-for-sale, at fair value (amortized cost of $9,972 and $9,488)	$10,491	$9,711
Short-term investments, at fair value	767	904
Other invested assets	126	170
Total investment portfolio	11,384	10,785
Cash	75	184
Premiums receivable, net of commissions payable	729	876
Ceded unearned premium reserve	381	452
Deferred acquisition costs	121	124
Reinsurance recoverable on unpaid losses	78	36
Salvage and subrogation recoverable	151	174
Credit derivative assets	68	94
Deferred tax asset, net	260	688
Financial guaranty variable interest entities’ assets, at fair value	1,402	2,565
Other assets	276	309
Total assets	14,925	16,287
Liabilities and shareholders’ equity
Unearned premium reserve	4,261	4,595
Loss and loss adjustment expense reserve	799	592
Reinsurance balances payable, net	107	148
Long-term debt	1,303	816
Credit derivative liabilities	963	1,787
Current income tax payable	5	44
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	1,277	1,790
Financial guaranty variable interest entities’ liabilities without recourse, at fair value	142	1,081
Other liabilities	310	319
Total liabilities	9,167	11,172
Commitments and contingencies
Common stock ($0.01 par value, 500,000,000 shares authorized; 158,306,661 and 182,177,866 shares issued and outstanding)	2	2
Additional paid-in capital	1,887	2,466
Retained earnings	3,494	2,482
Accumulated other comprehensive income, net of tax of $159 and $71	370	160
Deferred equity compensation (320,193 and 320,193 shares)	5	5
Total shareholders’ equity	5,758	5,115
Total liabilities and shareholders’ equity	$14,925	$16,287

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]
Available-for-sale Securities, Amortized Cost Basis	$9,972	$9,488
Common stock par value (per share)	$0.01	$0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	158,306,661	182,177,866
Common stock, shares outstanding	158,306,661	182,177,866
Accumulated other comprehensive income, tax provision	$159	$71
Deferred equity compensation, shares	320,193	320,193

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenues
Net earned premiums	$570		$752		$853
Net investment income	403		393		404
Net realized investment gains (losses):
Other-than-temporary impairment losses	-76		-32		-58
Less: portion of other-than-temporary impairment loss recognized in other comprehensive income	-1		10		-41
Net impairment loss	-75		-42		-17
Other net realized investment gains (losses)	15		94		18
Net realized investment gains (losses)	-60		52		1
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements	23		-42		-108
Net unrealized gains (losses)	800	[1]	107	[1]	-477	[1]
Net change in fair value of credit derivatives	823		65		-585
Fair value gains (losses) on committed capital securities	-11		10		-18
Fair value gains (losses) on financial guaranty variable interest entities	255		346		191
Other income (loss)	14		-10		108
Total revenues	1,994		1,608		954
Expenses
Loss and loss adjustment expenses	126		154		504
Amortization of deferred acquisition costs	25		12		14
Interest expense	92		82		92
Other operating expenses	220		218		212
Total expenses	463		466		822
Income (loss) before income taxes	1,531		1,142		132
Provision (benefit) for income taxes
Current	96		157		57
Deferred	347		177		-35
Total provision (benefit) for income taxes	443		334		22
Net income (loss)	$1,088		$808		$110
Earnings per share:
Basic (in dollars per share)	$6.30	[2]	$4.32	[2]	$0.58
Diluted (in dollars per share)	$6.26	[2]	$4.30	[2]	$0.57
Dividends (in dollars per share)	$0.44	[2]	$0.40	[2]	$0.36
[1]	Except for net estimated credit impairments (i.e., net expected loss to be paid as discussed in Note 6), the unrealized gains and losses on credit derivatives are expected to reduce to zero as the exposure approaches its maturity date. With considerable volatility continuing in the market, unrealized gains (losses) on credit derivatives may fluctuate significantly in future periods.
[2]	Per share amounts for the quarters and the full years have each been calculated separately. Accordingly, quarterly amounts may not sum up to the annual amounts because of differences in the average common shares outstanding during each period and, with regard to diluted per share amounts only, because of the inclusion of the effect of potentially dilutive securities only in the periods in which such effect would have been dilutive.

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income (loss)	$1,088	$808	$110
Unrealized holding gains (losses) arising during the period on:
Investments with no other-than-temporary impairment, net of tax provision (benefit) of $80, $(106) and $56	196	-309	148
Investments with other-than-temporary impairment, net of tax provision (benefit) of $(9), $(17) and $(2)	-20	-35	-7
Unrealized holding gains (losses) arising during the period, net of tax	176	-344	141
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(21), $5 and $(7)	-41	14	-4
Change in net unrealized gains on investments	217	-358	145
Other, net of tax provision	-7	3	2
Other comprehensive income (loss)	210	-355	147
Comprehensive income (loss)	$1,298	$453	$257

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Investments with no other-than-temporary impairment, tax provision (benefit)	$80	($106)	$56
Investments with other-than-temporary impairment, tax provision (benefit)	-9	-17	-2
Reclassification adjustment for gains (losses) included in net income (loss), tax provision (benefit)	($21)	$5	($7)

Consolidated_Statement_of_Shar

Consolidated Statement of Shareholders' Equity (USD $)	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss) [Member]	Deferred Equity Compensation
In Millions, except Share data, unless otherwise specified
Beginning balance at Dec. 31, 2011	$4,652	$2	$2,570	$1,708	$368	$4
Beginning balance (in shares) at Dec. 31, 2011		182,235,798
Increase (Decrease) in Shareholders' Equity
Net Income	110			110
Dividends (2012 $0.36, 2013 $0.40, 2014 $0.44 per share)	-69			-69
Common stock issuance, net (in shares)		13,428,770
Common stock issuance, net	173		173
Common stock repurchases (in shares)		-2,066,759
Common stock repurchases	-24		-24
Share-based compensation and other (in shares)		405,488
Share-based compensation and other	5		5
Other comprehensive income (loss)	147				147
Ending balance at Dec. 31, 2012	4,994	2	2,724	1,749	515	4
Ending balance (in shares) at Dec. 31, 2012		194,003,297
Increase (Decrease) in Shareholders' Equity
Net Income	808			808
Dividends (2012 $0.36, 2013 $0.40, 2014 $0.44 per share)	-75			-75
Common stock repurchases (in shares)		-12,512,759
Common stock repurchases	-264		-264
Share-based compensation and other (in shares)		687,328
Share-based compensation and other	7		6			1
Other comprehensive income (loss)	-355				-355
Ending balance at Dec. 31, 2013	5,115	2	2,466	2,482	160	5
Ending balance (in shares) at Dec. 31, 2013		182,177,866
Increase (Decrease) in Shareholders' Equity
Net Income	1,088			1,088
Dividends (2012 $0.36, 2013 $0.40, 2014 $0.44 per share)	-76			-76
Common stock repurchases (in shares)		-24,413,781
Common stock repurchases	-590		-590
Share-based compensation and other (in shares)		542,576
Share-based compensation and other	11		11
Other comprehensive income (loss)	210				210
Ending balance at Dec. 31, 2014	$5,758	$2	$1,887	$3,494	$370	$5
Ending balance (in shares) at Dec. 31, 2014		158,306,661

Consolidated_Statement_of_Shar1

Consolidated Statement of Shareholders' Equity (Parenthetical) (USD $)

3 Months Ended

12 Months Ended

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Statement of Stockholders' Equity [Abstract]

Dividends, per share (in dollars per share)

$0.11

[1]

$0.11

[1]

$0.11

[1]

$0.11

[1]

$0.10

[1]

$0.10

[1]

$0.10

[1]

$0.10

[1]

$0.09

$0.44

[1]

$0.40

[1]

$0.36

[1]

Per share amounts for the quarters and the full years have each been calculated separately. Accordingly, quarterly amounts may not sum up to the annual amounts because of differences in the average common shares outstanding during each period and, with regard to diluted per share amounts only, because of the inclusion of the effect of potentially dilutive securities only in the periods in which such effect would have been dilutive.

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Operating Activities:
Net Income	$1,088		$808		$110
Adjustments to reconcile net income to net cash flows provided by operating activities:
Non-cash interest and operating expenses	23		19		18
Net amortization of premium (discount) on investments	-16		-8		8
Provision (benefit) for deferred income taxes	347		177		-35
Net realized investment losses (gains)	60		-52		-1
Net unrealized losses (gains) on credit derivatives	-800	[1]	-107	[1]	477	[1]
Fair value loss (gains) on committed capital securities	11		-10		18
Change in deferred acquisition costs	3		-8		18
Change in premiums receivable, net of commissions payable	108		86		48
Change in ceded unearned premium reserve	69		109		141
Change in unearned premium reserve	-332		-612		-749
Change in loss and loss adjustment expense reserve, net	182		136		-258
Change in current income tax	-45		30		129
Change in financial guaranty variable interest entities' assets and liabilities, net	-170		-295		-7
(Purchases) sales of trading securities, net	78		-16		-59
Other	-29		-13		-23
Net cash flows provided by (used in) operating activities	577		244		-165
Fixed-maturity securities:
Purchases	-2,801		-1,886		-1,649
Sales	1,251		1,029		912
Maturities	877		883		1,105
Sales (purchases) of short-term investments, net	158		-87		29
Net proceeds from paydowns on financial guaranty variable interest entities’ assets	408		663		545
Acquisition of MAC, net of cash acquired	0		0		-91
Other	11		79		92
Net cash flows provided by (used in) investing activities	-96		681		943
Financing activities
Proceeds from issuances of common stock	0		0		173
Dividends paid	-76		-75		-69
Repurchases of common stock	-590		-264		-24
Share activity under option and incentive plans	1		-1		-3
Net paydowns of financial guaranty variable entities’ liabilities	-396		-511		-724
Net proceeds from issuance of long-term debt	495		0		0
Repayment of long-term debt	-19		-27		-209
Net cash flows provided by (used in) financing activities	-585		-878		-856
Effect of foreign exchange rate changes	-5		-1		1
Increase (decrease) in cash	-109		46		-77
Cash at beginning of period	184		138		215
Cash at end of period	75		184		138
Supplemental cash flow information
Income taxes	122		110		-24
Interest	$86		$76		$85
[1]	Except for net estimated credit impairments (i.e., net expected loss to be paid as discussed in Note 6), the unrealized gains and losses on credit derivatives are expected to reduce to zero as the exposure approaches its maturity date. With considerable volatility continuing in the market, unrealized gains (losses) on credit derivatives may fluctuate significantly in future periods.

Business_and_Basis_of_Presenta

Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Basis of Presentation	Business and Basis of Presentation
	Business
	Assured Guaranty Ltd. (“AGL” and, together with its subsidiaries, “Assured Guaranty” or the “Company”) is a Bermuda-based holding company that provides, through its operating subsidiaries, credit protection products to the United States (“U.S.”) and international public finance (including infrastructure) and structured finance markets. The Company applies its credit underwriting judgment, risk management skills and capital markets experience to offer financial guaranty insurance that protects holders of debt instruments and other monetary obligations from defaults in scheduled payments. If an obligor defaults on a scheduled payment due on an obligation, including a scheduled principal or interest payment (“Debt Service”), the Company is required under its unconditional and irrevocable financial guaranty to pay the amount of the shortfall to the holder of the obligation. The Company markets its financial guaranty insurance directly to issuers and underwriters of public finance and structured finance securities as well as to investors in such obligations. The Company guarantees obligations issued principally in the U.S. and the United Kingdom ("U.K."), and also guarantees obligations issued in other countries and regions, including Australia and Western Europe.
	In the past, the Company sold credit protection by issuing policies that guaranteed payment obligations under credit derivatives, primarily credit default swaps ("CDS"). Financial guaranty contracts accounted for as credit derivatives are generally structured such that the circumstances giving rise to the Company’s obligation to make loss payments are similar to those for financial guaranty insurance contracts. The Company’s credit derivative transactions are governed by International Swaps and Derivative Association, Inc. (“ISDA”) documentation. The Company has not entered into any new CDS in order to sell credit protection since the beginning of 2009, when regulatory guidelines were issued that limited the terms under which such protection could be sold. The capital and margin requirements applicable under the Dodd-Frank Wall Street Reform and Consumer Protection Act (the “Dodd-Frank Act”) also contributed to the Company not entering into such new CDS since 2009. The Company actively pursues opportunities to terminate existing CDS, which have the effect of reducing future fair value volatility in income and/or reducing rating agency capital charges.
	Basis of Presentation
	The consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and, in the opinion of management, reflect all adjustments that are of a normal recurring nature, necessary for a fair statement of the financial condition, results of operations and cash flows of the Company and its consolidated financial guaranty variable interest entities (“FG VIEs”) for the periods presented. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
	The consolidated financial statements include the accounts of AGL, its direct and indirect subsidiaries, (collectively, the “Subsidiaries”), and its consolidated FG VIEs. Intercompany accounts and transactions between and among all consolidated entities have been eliminated. Certain prior year balances have been reclassified to conform to the current year's presentation.
	The Company's principal insurance company subsidiaries are:
	•	Assured Guaranty Municipal Corp. ("AGM"), domiciled in New York;
	•	Municipal Assurance Corp. ("MAC"), domiciled in New York;
	•	Assured Guaranty Corp. ("AGC"), domiciled in Maryland;
	•	Assured Guaranty (Europe) Ltd. ("AGE"), organized in the United Kingdom; and
	•	Assured Guaranty Re Ltd. (“AG Re”), domiciled in Bermuda.
	On December 22, 2014, AGC entered into an agreement to purchase all of the issued and outstanding capital stock of Radian Asset Assurance Inc. ("Radian Asset"), a New York domiciled financial guaranty insurer that ceased writing new business in 2008, for $810 million in cash (subject to adjustment for dividends paid and expenses incurred prior to closing). The Company believes that consummation of the acquisition and the subsequent merger of Radian Asset with and into AGC, which are expected to be completed in the first half of 2015, will enhance the financial condition of AGC and the Company. As of December 31, 2014, Radian Asset had an insured portfolio of statutory net par outstanding of $10 billion public finance obligations and $8 billion structured finance obligations. As of December 31, 2014, Radian Asset had approximately $1.3 billion of qualified statutory capital.
	MAC was purchased from Radian Asset in 2012 for $91 million in cash. Upon acquisition, the Company recorded $16 million in indefinite lived intangible assets, which represented the value of MAC's insurance licenses. MAC commenced underwriting U.S. public finance business in August 2013. MAC is indirectly owned by AGM and AGC. See Note 12, Insurance Company Regulatory Requirements.
	The Company’s organizational structure includes various holding companies, two of which—Assured Guaranty US Holdings Inc. (“AGUS”) and Assured Guaranty Municipal Holdings Inc. (“AGMH”) – have public debt outstanding. See Note 17, Long-Term Debt and Credit Facilities.
	Significant Accounting Policies
	The Company revalues assets, liabilities, revenue and expenses denominated in non-U.S. currencies into U.S. dollars using applicable exchange rates. Gains and losses relating to translating foreign functional currency financial statements for U.S. GAAP reporting are recorded in other comprehensive income (loss) ("OCI"). Gains and losses relating to transactions in foreign denominations in subsidiaries where the functional currency is the U.S. dollar, are reported in the consolidated statement of operations.
	The chief operating decision maker manages the operations of the Company at a consolidated level. Therefore, all results of operations are reported as one segment.
	Other significant accounting policies are included in the following notes.
	Significant Accounting Policies
	Premium revenue recognition	Note 4
	Policy acquisition cost	Note 5
	Expected loss to be paid (Insurance, Credit Derivatives and FG VIE contracts)	Note 6
	Loss and loss adjustment expense (Insurance Contracts)	Note 7
	Fair value measurement	Note 8
	Credit derivatives (at Fair Value)	Note 9
	Variable interest entities (at Fair Value)	Note 10
	Investments and Cash	Note 11
	Income Taxes	Note 13
	Earnings per share	Note 18
	Stock based compensation	Note 20

Rating_Actions

Rating Actions	12 Months Ended
	Dec. 31, 2014
Rating Actions [Abstract]
Rating Actions	Rating Actions
	When a rating agency assigns a public rating to a financial obligation guaranteed by one of AGL’s insurance company subsidiaries, it generally awards that obligation the same rating it has assigned to the financial strength of the AGL subsidiary that provides the guaranty. Investors in products insured by AGL’s insurance company subsidiaries frequently rely on ratings published by the rating agencies because such ratings influence the trading value of securities and form the basis for many institutions’ investment guidelines as well as individuals’ bond purchase decisions. Therefore, the Company manages its business with the goal of achieving strong financial strength ratings. However, the methodologies and models used by rating agencies differ, presenting conflicting goals that may make it inefficient or impractical to reach the highest rating level. The methodologies and models are not fully transparent, contain subjective elements and data (such as assumptions about future market demand for the Company’s products) and change frequently. Ratings are subject to continuous review and revision or withdrawal at any time. If the financial strength ratings of one (or more) of the Company’s insurance subsidiaries were reduced below current levels, the Company expects it could have adverse effects on the impacted subsidiary's future business opportunities as well as the premiums the impacted subsidiary could charge for its insurance policies.
	In the last several years, Standard & Poor's Ratings Services ("S&P") and Moody's Investors Service, Inc. ("Moody's") have changed, multiple times, their financial strength ratings of the Company's insurance subsidiaries, or changed the outlook on such ratings. More recently, Kroll Bond Rating Agency ("KBRA") has assigned financial strength ratings to some of the Company's insurance subsidiaries. The rating agencies' most recent actions and proposals related to the Company's insurance subsidiaries are:
	•	On March 18, 2014, S&P upgraded the financial strength ratings of all of AGL's insurance subsidiaries to AA (stable outlook) from AA- (stable outlook); it affirmed such ratings in a credit analysis issued on July 2, 2014.
	•	On July 2, 2014, Moody's affirmed the ratings of AGL and its subsidiaries, but changed to negative the outlook of the financial strength ratings of AGC and its subsidiary Assured Guaranty (UK) Ltd. ("AGUK").
	•	On August 4, 2014, KBRA affirmed MAC's AA+ (stable outlook) financial strength rating.
	•	On November 13, 2014, KBRA assigned a financial strength rating of AA+ (stable outlook) to AGM.
	•	On January 20, 2015, Moody's adopted changes to its credit methodology for financial guaranty insurance companies, and on February 18, 2015 Moody's published a credit opinion maintaining its existing ratings of AGL and its subsidiaries under that new methodology.
	There can be no assurance that any of the rating agencies will not take negative action on their financial strength ratings of the Company's insurance subsidiaries in the future.
	For a discussion of the effects of rating actions on the Company, see the following:
	•	Note 7, Financial Guaranty Insurance Losses
	•	Note 9, Financial Guaranty Contracts Accounted for as Credit Derivatives
	•	Note 14, Reinsurance and Other Monoline Exposures
	•	Note 17, Long-Term Debt and Credit Facilities (regarding the impact on the Company's insured leveraged lease transactions)

Outstanding_Exposure

Outstanding Exposure	12 Months Ended
	Dec. 31, 2014
Outstanding Exposure Disclosure
Outstanding Exposure	Outstanding Exposure
	The Company’s financial guaranty contracts are written in either insurance or credit derivative form, but collectively are considered financial guaranty contracts. The Company seeks to limit its exposure to losses by underwriting obligations that are investment grade at inception, or in the case of restructurings of troubled credits, the Company may underwrite new issuances that one or more of the rating agencies may rate below-investment-grade ("BIG") as part of its loss mitigation strategy. The Company diversifies its insured portfolio across asset classes and, in the structured finance portfolio, maintains rigorous subordination or collateralization requirements. Reinsurance is utilized in order to reduce net exposure to certain insured transactions.
	Public finance obligations insured by the Company consist primarily of general obligation bonds supported by the taxing powers of U.S. state or municipal governmental authorities, as well as tax-supported bonds, revenue bonds and other obligations supported by covenants from state or municipal governmental authorities or other municipal obligors to impose and collect fees and charges for public services or specific infrastructure projects. The Company also includes within public finance obligations those obligations backed by the cash flow from leases or other revenues from projects serving substantial public purposes, including utilities, toll roads, health care facilities and government office buildings.
	Structured finance obligations insured by the Company are generally issued by special purpose entities, including variable interest entities ("VIEs"), and backed by pools of assets having an ascertainable cash flow or market value or other specialized financial obligations. Some of these VIEs are consolidated as described in Note 10, Consolidated Variable Interest Entities. Unless otherwise specified, the outstanding par and Debt Service amounts presented in this note include outstanding exposures on VIEs whether or not they are consolidated.
	Significant Risk Management Activities
	The Portfolio Risk Management Committee, which includes members of senior management and senior credit and surveillance officers, sets specific risk policies and limits and is responsible for enterprise risk management, establishing the Company's risk appetite, credit underwriting of new business, surveillance and work-out.
	Surveillance personnel are responsible for monitoring and reporting on all transactions in the insured portfolio. The primary objective of the surveillance process is to monitor trends and changes in transaction credit quality, detect any deterioration in credit quality, and recommend to management such remedial actions as may be necessary or appropriate. All transactions in the insured portfolio are assigned internal credit ratings, and surveillance personnel are responsible for recommending adjustments to those ratings to reflect changes in transaction credit quality.
	Work-out personnel are responsible for managing work-out and loss mitigation situations, working with surveillance and legal personnel (as well as outside vendors) as appropriate. They develop strategies for the Company to enforce its contractual rights and remedies and to mitigate its losses, engage in negotiation discussions with transaction participants and, when necessary, manage (along with legal personnel) the Company's litigation proceedings.
	Surveillance Categories
	The Company segregates its insured portfolio into investment grade and BIG surveillance categories to facilitate the appropriate allocation of resources to monitoring and loss mitigation efforts and to aid in establishing the appropriate cycle for periodic review for each exposure. BIG exposures include all exposures with internal credit ratings below BBB-. The Company’s internal credit ratings are based on internal assessments of the likelihood of default and loss severity in the event of default. Internal credit ratings are expressed on a ratings scale similar to that used by the rating agencies and are generally reflective of an approach similar to that employed by the rating agencies, except that the Company's internal credit ratings focus on future performance rather than lifetime performance.
	The Company monitors its investment grade credits to determine whether any new credits need to be internally downgraded to BIG and refreshes its internal credit ratings on individual credits in quarterly, semi-annual or annual cycles based on the Company’s view of the credit’s quality, loss potential, volatility and sector. Ratings on credits in sectors identified as under the most stress or with the most potential volatility are reviewed every quarter. The Company’s credit ratings on assumed credits are based on the Company’s reviews of low-rated credits or credits in volatile sectors, unless such information is not available, in which case, the ceding company’s credit rating of the transactions are used. The Company models the performance of many of its structured finance transactions as part of its periodic internal credit rating review of them. The Company models most assumed residential mortgage-backed security ("RMBS") credits with par above $1 million, as well as certain RMBS credits below that amount.
	Credits identified as BIG are subjected to further review to determine the probability of a loss. See Note 6, Expected Loss to be Paid, for additional information. Surveillance personnel then assign each BIG transaction to the appropriate BIG surveillance category based upon whether a future loss is expected and whether a claim has been paid. For surveillance purposes, the Company calculates present value using a constant discount rate of 4.5%-5% depending on the insurance subsidiary. (A risk-free curve rate is used for calculating the expected loss for financial statement measurement purposes.)
	More extensive monitoring and intervention is employed for all BIG surveillance categories, with internal credit ratings reviewed quarterly. The Company expects “future losses” on a transaction when the Company believes there is at least a 50% chance that, on a present value basis, it will pay more claims over the future of that transaction than it will have reimbursed. The three BIG categories are:
	•	BIG Category 1: Below-investment-grade transactions showing sufficient deterioration to make future losses possible, but for which none are currently expected.
	•	BIG Category 2: Below-investment-grade transactions for which future losses are expected but for which no claims (other than liquidity claims which is a claim that the Company expects to be reimbursed within one year) have yet been paid.
	•	BIG Category 3: Below-investment-grade transactions for which future losses are expected and on which claims (other than liquidity claims) have been paid.
	Components of Outstanding Exposure
	Unless otherwise noted, ratings disclosed herein on the Company's insured portfolio reflect its internal ratings. The Company classifies those portions of risks benefiting from reimbursement obligations collateralized by eligible assets held in trust in acceptable reimbursement structures as the higher of 'AA' or their current internal rating. The Company excludes amounts attributable to loss mitigation securities (unless otherwise indicated) from par and Debt Service outstanding, because it manages such securities as investments and not insurance exposure.
	Financial Guaranty
	Debt Service Outstanding
		Gross Debt Service								Net Debt Service
		Outstanding								Outstanding
		December 31,				December 31,				December 31,				December 31,
		2014				2013				2014				2013
		(in millions)
	Public finance	$	587,245			$	650,924			$	553,612			$	610,011
	Structured finance	59,477				86,456				56,010				80,524
	Total financial guaranty	$	646,722			$	737,380			$	609,622			$	690,535
	In addition to the amounts shown in the table above, the Company’s net mortgage guaranty insurance debt service was approximately $127 million as of December 31, 2014 related to loans originated in Ireland and $152 million as of December 31, 2013 related to loans originated in Ireland and U.K..
	Financial Guaranty Portfolio by Internal Rating
	As of December 31, 2014
			Public Finance							Public Finance						Structured Finance						Structured Finance				Total
			U.S.							Non-U.S.						U.S						Non-U.S
	Rating		Net Par				%			Net Par				%		Net Par			%			Net Par		%		Net Par		%
	Category		Outstanding							Outstanding						Outstanding						Outstanding				Outstanding
			(dollars in millions)
	AAA		$	4,082			1.3	%		$	615			2	%	$	20,037		48.7	%		$	5,409	59.6	%	$	30,143	7.5	%
	AA		90,464				28.1			2,785				8.9		8,213			19.9			503		5.5		101,965		25.3
	A		176,298				54.7			7,192				22.9		2,940			7.1			445		4.9		186,875		46.3
	BBB		43,429				13.5			19,363				61.7		1,795			4.4			1,912		21.1		66,499		16.4
	BIG		7,850				2.4			1,404				4.5		8,186			19.9			807		8.9		18,247		4.5
	Total net par outstanding (1)		$	322,123			100	%		$	31,359			100	%	$	41,171		100	%		$	9,076	100	%	$	403,729	100	%
	_____________________
	-1	Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.
	Financial Guaranty Portfolio by Internal Rating
	As of December 31, 2013
			Public Finance							Public Finance						Structured Finance						Structured Finance				Total
			U.S.							Non-U.S.						U.S						Non-U.S
	Rating		Net Par				%			Net Par				%		Net Par			%			Net Par		%		Net Par		%
	Category		Outstanding							Outstanding						Outstanding						Outstanding				Outstanding
			(dollars in millions)
	AAA		$	4,998			1.4	%		$	1,016			3	%	$	32,317		54.9	%		$	9,684	69.1	%	$	48,015	10.5	%
	AA		107,503				30.5			422				1.2		9,431			16			577		4.1		117,933		25.7
	A		192,841				54.8			9,453				27.9		2,580			4.4			742		5.3		205,616		44.8
	BBB		37,745				10.7			21,499				63.2		3,815			6.4			1,946		13.9		65,005		14.1
	BIG		9,094				2.6			1,608				4.7		10,764			18.3			1,072		7.6		22,538		4.9
	Total net par outstanding (1)		$	352,181			100	%		$	33,998			100	%	$	58,907		100	%		$	14,021	100	%	$	459,107	100	%
	_____________________
	-1	Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of December 31, 2013, which are primarily in the BIG category.
	Financial Guaranty Portfolio
	by Sector
		Gross Par Outstanding								Ceded Par Outstanding							Net Par Outstanding
	Sector	As of December 31, 2014				As of December 31, 2013				As of December 31, 2014				As of December 31, 2013			As of December 31, 2014			As of December 31, 2013
		(dollars in millions)
Public finance:
U.S.:
General obligation	$	144,714			$	160,751			$	4,438			$	5,474		$	140,276		$	155,277
Tax backed	65,600				70,552				3,075				3,728			62,525			66,824
Municipal utilities	53,471				57,893				1,381				1,569			52,090			56,324
Transportation	28,914				32,514				1,091				1,684			27,823			30,830
Healthcare	16,225				17,663				1,377				1,531			14,848			16,132
Higher education	13,485				14,470				386				399			13,099			14,071
Infrastructure finance	5,098				5,014				917				900			4,181			4,114
Housing	2,880				3,518				101				132			2,779			3,386
Investor-owned utilities	944				992				0				1			944			991
Other public finance—U.S.	3,575				4,249				17				17			3,558			4,232
Total public finance—U.S.	334,906				367,616				12,783				15,435			322,123			352,181
Non-U.S.:
Infrastructure finance	15,091				17,373				2,283				2,670			12,808			14,703
Regulated utilities	14,582				15,502				3,668				4,297			10,914			11,205
Pooled infrastructure	2,565				2,754				145				234			2,420			2,520
Other public finance—non-U.S.	6,216				6,645				999				1,075			5,217			5,570
Total public finance—non-U.S.	38,454				42,274				7,095				8,276			31,359			33,998
Total public finance	373,360				409,890				19,878				23,711			353,482			386,179
Structured finance:
U.S.:
Pooled corporate obligations	21,791				32,955				1,145				1,630			20,646			31,325
RMBS	10,109				14,542				692				821			9,417			13,721
Insurance securitizations	3,480				3,082				47				47			3,433			3,035
Financial product	2,276				2,709				—				—			2,276			2,709
Consumer receivables	2,157				2,257				58				59			2,099			2,198
Commercial mortgage-backed securities ("CMBS") and other commercial real estate related exposures	1,979				3,990				22				38			1,957			3,952
Commercial receivables	567				918				7				7			560			911
Structured credit	71				71				2				2			69			69
Other structured finance—U.S.	858				2,067				144				1,080			714			987
Total structured finance—U.S.	43,288				62,591				2,117				3,684			41,171			58,907
Non-U.S.:
Pooled corporate obligations	7,439				12,232				835				1,174			6,604			11,058
Commercial receivables	965				1,286				21				23			944			1,263
RMBS	893				1,296				99				150			794			1,146
Structured credit	9				197				—				21			9			176
Other structured finance—non-U.S.	750				403				25				25			725			378
Total structured finance—non-U.S.	10,056				15,414				980				1,393			9,076			14,021
Total structured finance	53,344				78,005				3,097				5,077			50,247			72,928
Total net par outstanding	$	426,704			$	487,895			$	22,975			$	28,788		$	403,729		$	459,107
In addition to amounts shown in the tables above, the Company had outstanding commitments to provide guaranties of $276 million for structured finance and $248 million for public finance obligations at December 31, 2014. The structured finance commitments include the unfunded component of pooled corporate and other transactions. The expiration dates for the public finance commitments range between January 15, 2015 and February 17, 2017, with $124 million expiring prior to December 31, 2015. The commitments are contingent on the satisfaction of all conditions set forth in them and may expire unused or be canceled at the counterparty’s request. Therefore, the total commitment amount does not necessarily reflect actual future guaranteed amounts.
Actual maturities of insured obligations could differ from contractual maturities because borrowers have the right to call or prepay certain obligations with or without call or prepayment penalties. The expected maturities of structured finance obligations are, in general, considerably shorter than the contractual maturities for such obligations.
Expected Amortization of
Net Par Outstanding
As of December 31, 2014
	Public Finance				Structured Finance				Total
	(in millions)
0 to 5 years	$	98,431			$	36,482			$	134,913
5 to 10 years	75,279				5,454				80,733
10 to 15 years	67,354				2,874				70,228
15 to 20 years	51,139				2,412				53,551
20 years and above	61,279				3,025				64,304
Total net par outstanding	$	353,482			$	50,247			$	403,729
Components of BIG Portfolio
Components of BIG Net Par Outstanding
(Insurance and Credit Derivative Form)
As of December 31, 2014
	BIG Net Par Outstanding															Net Par
	BIG 1				BIG 2				BIG 3				Total BIG			Outstanding
									(in millions)
First lien U.S. RMBS:
Prime first lien	$	68			$	33			$	252			$	353		$	471
Alt-A first lien	585				531				725				1,841			2,532
Option ARM	47				18				118				183			407
Subprime	156				654				765				1,575			4,051
Second lien U.S. RMBS:
Closed-end second lien	—				19				115				134			218
Home equity lines of credit (“HELOCs”)	1,012				36				509				1,557			1,738
Total U.S. RMBS	1,868				1,291				2,484				5,643			9,417
Trust preferred securities (“TruPS”)	997				—				336				1,333			4,326
Other structured finance	1,021				240				756				2,017			36,504
U.S. public finance	6,577				1,156				117				7,850			322,123
Non-U.S. public finance	1,402				2				—				1,404			31,359
Total	$	11,865			$	2,689			$	3,693			$	18,247		$	403,729
Components of BIG Net Par Outstanding
(Insurance and Credit Derivative Form)
As of December 31, 2013
	BIG Net Par Outstanding															Net Par
	BIG 1				BIG 2				BIG 3				Total BIG			Outstanding
									(in millions)
First lien U.S. RMBS:
Prime first lien	$	52			$	321			$	30			$	403		$	541
Alt-A first lien	656				1,137				935				2,728			3,590
Option ARM	71				60				467				598			937
Subprime	297				908				740				1,945			6,130
Second lien U.S. RMBS:
Closed-end second lien	8				20				118				146			244
HELOCs	1,499				20				378				1,897			2,279
Total U.S. RMBS	2,583				2,466				2,668				7,717			13,721
TruPS	1,587				135				—				1,722			4,970
Other structured finance	1,367				309				721				2,397			54,237
U.S. public finance	8,205				440				449				9,094			352,181
Non-U.S. public finance	1,009				599				—				1,608			33,998
Total	$	14,751			$	3,949			$	3,838			$	22,538		$	459,107
BIG Net Par Outstanding
and Number of Risks
As of December 31, 2014
		Net Par Outstanding												Number of Risks(2)
Description		Financial				Credit				Total				Financial		Credit		Total
		Guaranty				Derivative								Guaranty		Derivative
		Insurance(1)												Insurance(1)
		(dollars in millions)
BIG:
Category 1		$	10,195			$	1,670			$	11,865			164		18		182
Category 2		2,135				554				2,689				75		14		89
Category 3		2,892				801				3,693				119		24		143
Total BIG		$	15,222			$	3,025			$	18,247			358		56		414
BIG Net Par Outstanding
and Number of Risks
As of December 31, 2013
		Net Par Outstanding												Number of Risks(2)
Description		Financial				Credit				Total				Financial		Credit		Total
		Guaranty				Derivative								Guaranty		Derivative
		Insurance(1)												Insurance(1)
		(dollars in millions)
BIG:
Category 1		$	12,391			$	2,360			$	14,751			185		25		210
Category 2		2,323				1,626				3,949				80		21		101
Category 3		3,031				807				3,838				119		27		146
Total BIG		$	17,745			$	4,793			$	22,538			384		73		457
_____________________
(1)    Includes net par outstanding for FG VIEs.
-2	A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments.
Geographic Distribution of Net Par Outstanding
The Company seeks to maintain a diversified portfolio of insured obligations designed to spread its risk across a number of geographic areas.
Geographic Distribution of
Net Par Outstanding
As of December 31, 2014
	Number of Risks			Net Par Outstanding				Percent of Total Net Par Outstanding
	(dollars in millions)
U.S.:
U.S. Public finance:
California	1,465			$	50,668			12.6	%
Pennsylvania	1,009			26,173				6.5
New York	995			26,044				6.5
Texas	1,239			25,449				6.3
Illinois	830			22,825				5.7
Florida	384			19,470				4.8
New Jersey	602			13,558				3.4
Michigan	668			12,739				3.2
Georgia	192			8,217				2
Ohio	507			7,818				1.9
Other states and U.S. territories	4,174			109,162				27
Total U.S. public finance	12,065			322,123				79.9
U.S. Structured finance (multiple states)	839			41,171				10.2
Total U.S.	12,904			363,294				90.1
Non-U.S.:
United Kingdom	114			19,856				4.9
Australia	26			4,121				1
Canada	10			3,526				0.9
France	20			2,820				0.7
Italy	9			1,501				0.4
Other	78			8,611				2
Total non-U.S.	257			40,435				9.9
Total	13,161			$	403,729			100	%
Exposure to the Selected European Countries
Several European countries continue to experience significant economic, fiscal and/or political strains such that the likelihood of default on obligations with a nexus to those countries may be higher than the Company anticipated when such factors did not exist. The European countries where the Company believes heightened uncertainties exist are: Hungary, Italy, Portugal and Spain (collectively, the “Selected European Countries”). The Company is closely monitoring its exposures in the Selected European Countries where it believes heightened uncertainties exist. Previously, the Company had included Ireland on this list but removed it during the third quarter of 2014 because of Ireland's strengthening economic performance and improving prospects; in 2014, Ireland's long-term foreign currency rating was upgraded one notch by S&P (to ‘A-’) and three notches by Moody’s (to ‘Baa1’). The Company’s direct economic exposure to the Selected European Countries (based on par for financial guaranty contracts and notional amount for financial guaranty contracts accounted for as derivatives) is shown in the following table, net of ceded reinsurance.
Net Direct Economic Exposure to Selected European Countries(1)
As of December 31, 2014
	Hungary				Italy				Portugal				Spain			Total
	(in millions)
Sovereign and sub-sovereign exposure:
Non-infrastructure public finance(2)	$	—			$	878			$	91			$	239		$	1,208
Infrastructure finance	313				13				11				135			472
Total sovereign and sub-sovereign exposure	313				891				102				374			1,680
Non-sovereign exposure:
Regulated utilities	—				220				—				—			220
RMBS	186				267				—				—			453
Total non-sovereign exposure	186				487				—				—			673
Total	$	499			$	1,378			$	102			$	374		$	2,353
Total BIG (See Note 6)	$	424			$	—			$	102			$	374		$	900
____________________
-1	While the Company’s exposures are shown in U.S. dollars, the obligations the Company insures are in various currencies, primarily Euros. One of the residential mortgage-backed securities included in the table above includes residential mortgages in both Italy and Germany, and only the portion of the transaction equal to the portion of the original mortgage pool in Italian mortgages is shown in the table.
-2	The exposure shown in the “Non-infrastructure public finance” category is from transactions backed by receivable payments from sub-sovereigns in Italy, Spain and Portugal. Sub-sovereign debt is debt issued by a governmental entity or government backed entity, or supported by such an entity, that is other than direct sovereign debt of the ultimate governing body of the country.
When the Company directly insures an obligation, it assigns the obligation to a geographic location or locations based on its view of the geographic location of the risk. The Company may also have direct exposures to the Selected European Countries in business assumed from unaffiliated monoline insurance companies, in which case the Company depends upon geographic information provided by the primary insurer.
The Company has excluded from the exposure tables above its indirect economic exposure to the Selected European Countries through policies it provides on pooled corporate and commercial receivables transactions. The Company calculates indirect exposure to a country by multiplying the par amount of a transaction insured by the Company times the percent of the relevant collateral pool reported as having a nexus to the country. On that basis, the Company has calculated exposure of $418 million of Selected European Countries (plus Greece) in transactions with $11.6 billion of net par outstanding. The indirect exposure to credits with a nexus to Greece is $12 million across several highly rated pooled corporate obligations with net par outstanding of $864 million.
Exposure to Puerto Rico
The Company insures general obligation bonds of the Commonwealth of Puerto Rico and various obligations of its related authorities and public corporations aggregating $4.9 billion net par as of December 31, 2014. The Company rates $4.7 billion net par of that amount BIG; included in that amount are the obligations of Puerto Rico Highway and Transportation Authority (“PRHTA”) (transportation), Puerto Rico Electric Power Authority (“PREPA”), and PRHTA (highway).
Puerto Rico has experienced significant general fund budget deficits in recent years. These deficits have been covered primarily with the net proceeds of bond issuances, interim financings provided by Government Development Bank for Puerto Rico (“GDB”) and, in some cases, one-time revenue measures or expense adjustment measures. In addition to high debt levels, Puerto Rico faces a challenging economic environment.
In June 2014, the Puerto Rico legislature passed the Puerto Rico Public Corporation Debt Enforcement and Recovery Act (the "Recovery Act") in order to provide a legislative framework for certain public corporations experiencing severe financial stress to restructure their debt, including PRHTA and PREPA. Subsequently, the Commonwealth stated PREPA might need to seek relief under the Recovery Act due to liquidity constraints, and disclosed PREPA had utilized approximately $42 million on deposit in its reserve account in order to pay debt service due on its bonds on July 1, 2014.
In August 2014, PREPA entered into forbearance agreements with the GDB, its bank lenders, and bondholders and financial guaranty insurers (including AGM and AGC) that hold or guarantee more than 60% of PREPA's outstanding bonds, in order to address its near-term liquidity issues. Creditors, including AGM and AGC, agreed not to exercise available rights and remedies until March 31, 2015, and the bank lenders agreed to extend the maturity of two revolving lines of credit to the same date. PREPA agreed it would continue to make principal and interest payments on its outstanding bonds, and interest payments on its lines of credit. It also agreed it would develop a five year business plan and a recovery program in respect of its operations; a preliminary business plan was released in December 2014. Creditors, including AGM and AGC, have begun discussions among themselves and with PREPA regarding potentially extending the forbearance agreements beyond March 31, 2015, but there can be no assurance that such discussions will result in such an extension.
Investors in bonds issued by PREPA had filed suit in the United States District Court for the District of Puerto Rico asserting the Recovery Act violates the U.S. Constitution. On February 6, 2015, the U.S. District Court for the District of Puerto Rico ruled the Recovery Act is preempted by the U.S. Bankruptcy Code and is therefore void; on February 19, 2015, the Commonwealth appealed the ruling to the U.S. Court of Appeals for the First Circuit. In addition, the Commonwealth's Resident Commissioner has introduced a bill to the U.S. Congress that, if passed, would enable the Commonwealth to authorize one or more of its public corporations to restructure their debts under chapter 9 of the U.S Bankruptcy Code if they were to become insolvent. The passage of the Recovery Act, its subsequent invalidation, and the introduction of legislation that would enable the Commonwealth to authorize chapter 9 protection for its public corporations have resulted in uncertainty among investors about the rights of creditors of the Commonwealth and its related authorities and public corporations.
Following the enactment of the Recovery Act, S&P, Moody’s and Fitch Ratings lowered the credit rating of the Commonwealth’s bonds and the ratings on certain of its public corporations. In February 2015, S&P and Moody’s each again lowered the credit rating of the Commonwealth's bonds and the ratings on certain of its public corporations. The Commonwealth has disclosed its liquidity has been adversely affected by rating agency downgrades and by the limited market access for its debt, and also noted it has relied on short-term financings and interim loans from the GDB and other private lenders, which reliance has constrained its liquidity and increased its near-term refinancing risk.
In December 2014, Puerto Rico's legislature approved a bill designed to stabilize PRHTA and improve the liquidity of the GDB. Signed by the governor on January 15, 2015, the legislation provides for certain tax revenues that would support PRHTA and require the transfer of certain liabilities and revenues from PHRTA to another authority, as well as requiring the transfer of the operations of poorly performing transit facilities to a new authority.
Puerto Rico
Gross Par and Gross Debt Service Outstanding
	Gross Par Outstanding								Gross Debt Service Outstanding
	December 31,				December 31,				December 31,				December 31,
	2014				2013				2014				2013
	(in millions)
Subject to the Now Voided Recovery Act (1)	$	3,058			$	3,279			$	5,326			$	5,748
Not subject to the Now Voided Recovery Act	2,977				3,517				4,748				5,599
Total	$	6,035			$	6,796			$	10,074			$	11,347
____________________
-1	On February 6, 2015, the U.S. District Court for the District of Puerto Rico ruled that the Recovery Act is preempted by the Federal Bankruptcy Code and is therefore void. On February 19, 2015, the Commonwealth appealed the ruling to the U.S. Court of Appeals for the First Circuit.
The following table shows the Company’s exposure to general obligation bonds of Puerto Rico and various obligations of its related authorities and public corporations.
Puerto Rico
Net Par Outstanding
		As of						As of
		31-Dec-14						31-Dec-13
		Total				Internal Rating		Total				Internal Rating
		(in millions)
Exposures subject to the Now Voided Recovery Act:
PRHTA (Transportation revenue)		$	844			BB-		$	872			BB-
PREPA		772				B-		860				BB-
Puerto Rico Aqueduct and Sewer Authority		384				BB-		384				BB-
PRHTA (Highway revenue)		273				BB		302				BB
Puerto Rico Convention Center District Authority		174				BB-		185				BB-
Puerto Rico Public Finance Corporation		—				—		44				B
Total		2,447						2,647
Exposures not subject to the Now Voided Recovery Act:
Commonwealth of Puerto Rico - General Obligation Bonds		1,672				BB		1,885				BB
Puerto Rico Municipal Finance Agency		399				BB-		450				BB-
Puerto Rico Sales Tax Financing Corporation		269				BBB		268				A-
Puerto Rico Public Buildings Authority		100				BB		139				BB
GDB		33				BB		33				BB
Puerto Rico Infrastructure Finance Authority		18				BB-		18				BB-
University of Puerto Rico		1				BB-		1				BB-
Total		2,492						2,794
Total net exposure to Puerto Rico		$	4,939					$	5,441
The following table shows the scheduled amortization of the general obligation bonds of Puerto Rico and various obligations of its related authorities and public corporations insured and rated BIG by the Company. The Company guarantees payments of interest and principal when those amounts are scheduled to be paid and cannot be required to pay on an accelerated basis. In the event that obligors default on their obligations, the Company would only be required to pay the shortfall between the principal and interest due in any given period and the amount paid by the obligors.
Amortization Schedule of Puerto Rico BIG Net Par Outstanding
and BIG Net Debt Service Outstanding
As of December 31, 2014
	Scheduled BIG Net Par Amortization												Scheduled BIG Net Debt Service Amortization
	Subject to the Now Voided Recovery Act				Not Subject to the Now Voided Recovery Act				Total				Subject to the Now Voided Recovery Act			Not Subject to the Now Voided Recovery Act			Total
	(in millions)
2015	$	126			$	205			$	331			$	249		$	319		$	568
2016	84				183				267				199			287			486
2017	41				166				207				153			262			415
2018	48				109				157				158			195			353
2019	61				126				187				168			207			375
2020	73				182				255				176			258			434
2021	51				58				109				151			124			275
2022	42				67				109				140			129			269
2023	102				40				142				198			99			297
2024	82				78				160				174			136			310
2025 - 2029	576				340				916				951			566			1,517
2030 - 2034	440				387				827				696			541			1,237
2035 - 2039	397				270				667				526			304			830
2040 - 2044	78				12				90				147			13			160
2045 - 2047	246				—				246				271			—			271
Total	$	2,447			$	2,223			$	4,670			$	4,357		$	3,440		$	7,797

Financial_Guaranty_Insurance_P

Financial Guaranty Insurance Premiums	12 Months Ended
	Dec. 31, 2014
Insurance [Abstract]
Financial Guaranty Insurance Premiums	Financial Guaranty Insurance Premiums
	The portfolio of outstanding exposures discussed in Note 3, Outstanding Exposure, includes financial guaranty contracts that meet the definition of insurance contracts as well as those that meet the definition of a derivative under GAAP. Amounts presented in this note relate only to financial guaranty insurance contracts, unless otherwise noted. See Note 9, Financial Guaranty Contracts Accounted for as Credit Derivatives for amounts that relate to CDS.
	Accounting Policies
	Accounting for financial guaranty contracts that meet the scope exception under derivative accounting guidance are subject to industry specific guidance for financial guaranty insurance. The accounting for contracts that fall under the financial guaranty insurance definition are consistent whether the contract was written on a direct basis, assumed from another financial guarantor under a reinsurance treaty, ceded to another insurer under a reinsurance treaty, or acquired in a business combination.
	Premium receivables comprise the present value of contractual or expected future premium collections discounted using the risk-free rate. Unearned premium reserve represents deferred premium revenue, less claim payments and recoveries received that have not yet been recognized in the statement of operations (“contra-paid”). The following discussion relates to the deferred premium revenue component of the unearned premium reserve, while the contra-paid is discussed in Note 7, Financial Guaranty Insurance Losses.
	The amount of deferred premium revenue at contract inception is determined as follows:
	•	For premiums received upfront on financial guaranty insurance contracts that were originally underwritten by the Company, deferred premium revenue is equal to the amount of cash received. Upfront premiums typically relate to public finance transactions.
	•	For premiums received in installments on financial guaranty insurance contracts that were originally underwritten by the Company, deferred premium revenue is the present value of either (1) contractual premiums due or (2) in cases where the underlying collateral is comprised of homogeneous pools of assets, the expected premiums to be collected over the life of the contract. To be considered a homogeneous pool of assets, prepayments must be contractually prepayable, the amount of prepayments must be probable, and the timing and amount of prepayments must be reasonably estimable. When the Company adjusts prepayment assumptions or expected premium collections, an adjustment is recorded to the deferred premium revenue, with a corresponding adjustment to the premium receivable, and prospective changes are recognized in premium revenues. Premiums receivable are discounted at the risk-free rate at inception and such discount rate is updated only when changes to prepayment assumptions are made that change the expected date of final maturity. Installment premiums typically relate to structured finance transactions, where the insurance premium rate is determined at the inception of the contract but the insured par is subject to prepayment throughout the life of the transaction.
	•	For financial guaranty insurance contracts acquired in a business combination, deferred premium revenue is equal to the fair value of the Company's stand-ready obligation portion of the insurance contract at the date of acquisition based on what a hypothetical similarly rated financial guaranty insurer would have charged for the contract at that date and not the actual cash flows under the insurance contract. The amount of deferred premium revenue may differ significantly from cash collections due primarily to fair value adjustments recorded in connection with a business combination.
	The Company recognizes deferred premium revenue as earned premium over the contractual period or expected period of the contract in proportion to the amount of insurance protection provided. As premium revenue is recognized, a corresponding decrease to the deferred premium revenue is recorded. The amount of insurance protection provided is a function of the insured principal amount outstanding. Accordingly, the proportionate share of premium revenue recognized in a given reporting period is a constant rate calculated based on the relationship between the insured principal amounts outstanding in the reporting period compared with the sum of each of the insured principal amounts outstanding for all periods. When an insured financial obligation is retired before its maturity, the financial guaranty insurance contract is extinguished. Any nonrefundable deferred premium revenue related to that contract is accelerated and recognized as premium revenue. When a premium receivable balance is deemed uncollectible, it is written off to bad debt expense.
	For reinsurance assumed contracts, earned premiums reported in the Company's consolidated statements of operations are calculated based upon data received from ceding companies, however, some ceding companies report premium data between 30 and 90 days after the end of the reporting period. The Company estimates earned premiums for the lag period.  Differences between such estimates and actual amounts are recorded in the period in which the actual amounts are determined. When installment premiums are related to reinsurance assumed contracts, the Company assesses the credit quality and liquidity of the ceding companies and the impact of any potential regulatory constraints to determine the collectability of such amounts.
	Financial Guaranty Insurance Premiums
	Deferred premium revenue ceded to reinsurers (ceded unearned premium reserve) is recorded as an asset. Direct, assumed and ceded earned premium revenue are presented together as net earned premiums in the statement of operations. Net earned premiums comprise the following:
	Net Earned Premiums
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Scheduled net earned premiums	$	415		$	470		$	581
	Acceleration of net earned premiums	136			263			249
	Accretion of discount on net premiums receivable	16			17			22
	Financial guaranty insurance net earned premiums	567			750			852
	Other	3			2			1
	Net earned premiums (1)	$	570		$	752		$	853
	___________________
	-1	Excludes $32 million, $60 million and $153 million for the year ended December 31, 2014, 2013 and 2012, respectively, related to consolidated FG VIEs.
	Components of
	Unearned Premium Reserve
		As of December 31, 2014									As of December 31, 2013
		Gross			Ceded			Net(1)			Gross			Ceded			Net(1)
		(in millions)
	Deferred premium revenue:
	Financial guaranty insurance	$	4,167		$	387		$	3,780		$	4,647		$	470		$	4,177
	Other	0			—			0			5			—			5
	Deferred premium revenue	$	4,167		$	387		$	3,780		$	4,652		$	470		$	4,182
	Contra-paid(2)	94			(6		)	100			(57		)	(18		)	(39		)
	Unearned premium reserve	$	4,261		$	381		$	3,880		$	4,595		$	452		$	4,143
	____________________
	-1	Excludes $125 million and $187 million deferred premium revenue and $42 million and $55 million of contra-paid related to FG VIEs as of December 31, 2014 and December 31, 2013, respectively.
	-2	See Note 7, "Financial Guaranty Insurance Losses– Insurance Contracts' Loss Information" for an explanation of "contra-paid".
	Gross Premium Receivable,
	Net of Commissions on Assumed Business
	Roll Forward
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Beginning of period, December 31	$	876		$	1,005		$	1,003
	Gross premium written, net of commissions on assumed business	171			145			211
	Gross premiums received, net of commissions on assumed business	(230		)	(259		)	(294		)
	Adjustments:
	Changes in the expected term	(66		)	(28		)	44
	Accretion of discount, net of commissions on assumed business	10			20			36
	Foreign exchange translation	(31		)	(1		)	13
	Consolidation/deconsolidation of FG VIEs	(1		)	—			(5		)
	Other adjustments	—			(6		)	(3		)
	End of period, December 31 (1)	$	729		$	876		$	1,005
	____________________
	-1	Excludes $19 million, $21 million and $29 million as of December 31, 2014 , 2013 and 2012, respectively, related to consolidated FG VIEs.
	Foreign exchange translation relates to installment premium receivables denominated in currencies other than the U.S. dollar. Approximately 51% and 48% of installment premiums at December 31, 2014 and 2013, respectively, are denominated in currencies other than the U.S. dollar, primarily the Euro and British Pound Sterling.
	The timing and cumulative amount of actual collections may differ from expected collections in the tables below due to factors such as foreign exchange rate fluctuations, counterparty collectability issues, accelerations, commutations and changes in expected lives.
	Expected Collections of
	Gross Premiums Receivable,
	Net of Commissions on Assumed Business
	(Undiscounted)
		As of December 31, 2014
	(in millions)
2015 (January 1 – March 31)	$	31
2015 (April 1 – June 30)	26
2015 (July 1 – September 30)	20
2015 (October 1 – December 31)	20
2016	74
2017	69
2018	62
2019	58
2020-2024	242
2025-2029	154
2030-2034	106
After 2034	102
Total(1)	$	964
____________________
-1	Excludes expected cash collections on FG VIEs of $25 million.
Scheduled Net Earned Premiums
	As of December 31, 2014
	(in millions)
2015 (January 1 – March 31)	$	93
2015 (April 1 – June 30)	91
2015 (July 1 – September 30)	89
2015 (October 1 – December 31)	86
Subtotal 2015	359
2016	332
2017	295
2018	269
2019	246
2020-2024	968
2025-2029	615
2030-2034	370
After 2034	326
Total present value basis(1)	3,780
Discount	208
Total future value	$	3,988
____________________
-1	Excludes scheduled net earned premiums on consolidated FG VIEs of $125 million.
Selected Information for Policies Paid in Installments
	As of			As of
	31-Dec-14			31-Dec-13
	(dollars in millions)
Premiums receivable, net of commission payable	$	729		$	876
Gross deferred premium revenue	1,370			1,576
Weighted-average risk-free rate used to discount premiums	3.5		%	3.4		%
Weighted-average period of premiums receivable (in years)	9.4			9.4

Financial_Guaranty_Insurance_A

Financial Guaranty Insurance Acquisition Costs	12 Months Ended
	Dec. 31, 2014
Insurance [Abstract]
Financial Guaranty Insurance Acquisition Costs	Financial Guaranty Insurance Acquisition Costs
	Accounting Policy
	Policy acquisition costs that are directly related and essential to successful insurance contract acquisition and ceding commission income on ceded reinsurance contracts are deferred for contracts accounted for as insurance. Amortization of deferred policy acquisition costs includes the accretion of discount on ceding commission income and expense. Acquisition costs associated with derivative contracts are not deferred.
	Direct costs related to the acquisition of new and renewal contracts that result directly from and are essential to the contract transaction are capitalized. These costs include expenses such as ceding commissions expense on assumed reinsurance contracts and the cost of underwriting personnel attributable to successful underwriting efforts. Ceding commission expense on assumed reinsurance contracts and ceding commission income on ceded reinsurance contracts that are associated with premiums received in installments are calculated at their contractually defined rates and included in deferred acquisition costs ("DAC"), with a corresponding offset to net premiums receivable or reinsurance balances payable. Management uses its judgment in determining the type and amount of costs to be deferred. The Company conducts an annual study to determine which operating costs qualify for deferral. Costs incurred for soliciting potential customers, market research, training, administration, unsuccessful acquisition efforts, and product development as well as all overhead type costs are charged to expense as incurred. DAC is amortized in proportion to net earned premiums. When an insured obligation is retired early, the remaining related DAC is expensed at that time.
	Expected losses, which include loss adjustment expenses (“LAE”), investment income, and the remaining costs of servicing the insured or reinsured business, are considered in determining the recoverability of DAC.
	Rollforward of
	Deferred Acquisition Costs
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Beginning of period	$	124		$	116		$	132
	Costs deferred during the period:
	Commissions on assumed and ceded business	7			9			(13		)
	Premium taxes	3			4			4
	Compensation and other acquisition costs	10			8			10
	Total	20			21			1
	Costs amortized during the period	(23		)	(13		)	(17		)
	End of period	$	121		$	124		$	116

Expected_Loss_to_be_Paid

Expected Loss to be Paid	12 Months Ended
	Dec. 31, 2014
Expected Losses [Abstract]
Expected Loss to be Paid	Expected Loss to be Paid
	The insured portfolio includes policies accounted for under three separate accounting models depending on the characteristics of the contract and the Company's control rights. The Company has paid and expects to pay future losses on policies which fall under each of the three accounting models. The following provides a summarized description of the three accounting models prescribed by GAAP with a reference to the notes that describe the accounting policies and required disclosures throughout this report. The three models are: (1) insurance, (2) derivative and (3) VIE consolidation.
	In order to effectively evaluate and manage the economics and liquidity of the entire insured portfolio, management compiles and analyzes loss information for all policies on a consistent basis. The Company monitors and assigns ratings and calculates expected losses in the same manner for all its exposures regardless of form or differing accounting models.
	This note provides information regarding expected claim payments to be made under all contracts in the insured portfolio. Net expected loss to be paid in the tables below consists of the present value of future: expected claim and LAE payments, expected recoveries of excess spread in the transaction structures, cessions to reinsurers, and expected recoveries for breaches of representations and warranties ("R&W") and other loss mitigation strategies.
	Accounting Policy
	Insurance Accounting
	For contracts accounted for as financial guaranty insurance, loss and LAE reserve is recorded only to the extent and for the amount that expected losses to be paid exceed unearned premium reserve. As a result, the Company has expected loss to be paid that have not yet been expensed. Such amounts will be recognized in future periods as deferred premium revenue amortizes into income. Expected loss to be paid is important from a liquidity perspective in that it represents the present value of amounts that the Company expects to pay or recover in future periods, regardless of the accounting model. Expected loss to be paid is an important measure used by management to analyze the net economic loss on all contacts. Expected loss to be expensed is important because it presents the Company's projection of incurred losses that will be recognized in future periods (excluding accretion of discount). See Note 7, Financial Guaranty Insurance Losses.
	Derivative Accounting, at Fair Value
	For contracts that do not meet the financial guaranty scope exception in the derivative accounting guidance (primarily due to the fact that the insured is not required to be exposed to the insured risk throughout the life of the contract), the Company records such credit derivative contracts at fair value on the consolidated balance sheet with changes in fair value recorded in the consolidated statement of operations. The fair value recorded on the balance sheet represents an exit price in a hypothetical market because the Company does not trade its credit derivative contracts. The fair value is determined using significant Level 3 inputs in an internally developed model while the expected loss to be paid (which represents the net present value of expected cash outflows) uses methodologies and assumptions consistent with financial guaranty insurance expected losses to be paid. See Note 8, Fair Value Measurement and Note 9, Financial Guaranty Contracts Accounted for as Credit Derivatives.
	VIE Consolidation, at Fair Value
	For financial guaranty insurance contracts issued on the debt of variable interest entities over which the Company is deemed to be the primary beneficiary due to its control rights, as defined in GAAP, the Company consolidates the FG VIE. The Company carries the assets and liabilities of the FG VIEs at fair value under the fair value option election. Management assesses the losses on the insured debt of the consolidated FG VIEs in the same manner as other financial guaranty insurance and credit derivative contracts. See Note 10, Consolidated Variable Interest Entities.
	Expected Loss to be Paid
	The expected loss to be paid is equal to the present value of expected future cash outflows for claim and LAE payments, net of inflows for expected salvage and subrogation (e.g. excess spread on the underlying collateral, and estimated and contractual recoveries for breaches of representations and warranties), using current risk-free rates. When the Company becomes entitled to the cash flow from the underlying collateral of an insured credit under salvage and subrogation rights as a result of a claim payment or estimated future claim payment, it reduces the expected loss to be paid on the contract. Net expected loss to be paid is defined as expected loss to be paid, net of amounts ceded to reinsurers.
	The current risk-free rate is based on the remaining period of the contract used in the premium revenue recognition calculation (i.e., the contractual or expected period, as applicable). The Company updates the discount rate each quarter and records the effect of such changes in economic loss development. Expected cash outflows and inflows are probability weighted cash flows that reflect the likelihood of all possible outcomes. The Company estimates the expected cash outflows and inflows using management's assumptions about the likelihood of all possible outcomes based on all information available to it. Those assumptions consider the relevant facts and circumstances and are consistent with the information tracked and monitored through the Company's risk-management activities.
	Economic Loss Development
	Economic loss development represents the change in net expected loss to be paid attributable to the effects of changes in assumptions based on observed market trends, changes in discount rates, accretion of discount and the economic effects of loss mitigation efforts.
	Expected loss to be paid and economic loss development include the effects of loss mitigation strategies such as negotiated and estimated recoveries for breaches of representations and warranties, and purchases of insured debt obligations. Additionally, in certain cases, issuers of insured obligations elected, or the Company and an issuer mutually agreed as part of a negotiation, to deliver the underlying collateral or insured obligation to the Company.
	In circumstances where the Company has purchased its own insured obligations that have expected losses, expected loss to be paid is reduced by the proportionate share of the insured obligation that is held in the investment portfolio. The difference between the purchase price of the obligation and the fair value excluding the value of the Company's insurance, is treated as a paid loss. Assets that are purchased by the Company are recorded in the investment portfolio, at fair value, excluding the value of the Company's insurance. See Note 11, Investments and Cash and Note 8, Fair Value Measurement.
	Loss Estimation Process
	The Company’s loss reserve committees estimate expected loss to be paid for all contracts. Surveillance personnel present analyses related to potential losses to the Company’s loss reserve committees for consideration in estimating the expected loss to be paid. Such analyses include the consideration of various scenarios with corresponding probabilities assigned to them. Depending upon the nature of the risk, the Company’s view of the potential size of any loss and the information available to the Company, that analysis may be based upon individually developed cash flow models, internal credit rating assessments and sector-driven loss severity assumptions or judgmental assessments. In the case of its assumed business, the Company may conduct its own analysis as just described or, depending on the Company’s view of the potential size of any loss and the information available to the Company, the Company may use loss estimates provided by ceding insurers. The Company’s loss reserve committees review and refresh the estimate of expected loss to be paid each quarter. The Company’s estimate of ultimate loss on a policy is subject to significant uncertainty over the life of the insured transaction due to the potential for significant variability in credit performance as a result of economic, fiscal and financial market variability over the long duration of most contracts. The determination of expected loss to be paid is an inherently subjective process involving numerous estimates, assumptions and judgments.
	The following tables present a roll forward of the present value of net expected loss to be paid for all contracts, whether accounted for as insurance, credit derivatives or FG VIEs, by sector, before and after the benefit for net expected recoveries for contractual breaches of R&W. The Company used weighted average risk-free rates for U.S. dollar denominated obligations, that ranged from 0.0% to 2.95% as of December 31, 2014 and 0.0% to 4.44% as of December 31, 2013.
	Net Expected Loss to be Paid
	Before Net Expected Recoveries for Breaches of R&W
	Roll Forward by Sector
	Year Ended December 31, 2014
		Net Expected				Economic Loss				(Paid)			Net Expected
		Loss to be				Development				Recovered			Loss to be
		Paid (Recovered) as of								Losses(1)			Paid (Recovered) as of
		December 31, 2013(2)											December 31, 2014(2)
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	25			$	(17	)		$	(2	)	$	6
	Alt-A first lien	578				(13		)		(155		)	410
	Option ARM	164				(45		)		(120		)	(1		)
	Subprime	422				43				(53		)	412
	Total first lien	1,189				(32		)		(330		)	827
	Second lien:
	Closed-end second lien	87				(3		)		9			93
	HELOCs	(71		)		35				17			(19		)
	Total second lien	16				32				26			74
	Total U.S. RMBS	1,205				0				(304		)	901
	TruPS	51				(28		)		—			23
	Other structured finance	120				96				2			218
	U.S. public finance	264				183				(144		)	303
	Non-U.S. public finance	57				(12		)		—			45
	Other insurance	(3		)		(1		)		—			(4		)
	Total	$	1,694			$	238			$	(446	)	$	1,486
	Net Expected Loss to be Paid
	Before Net Expected Recoveries for Breaches of R&W
	Roll Forward by Sector
	Year Ended December 31, 2013
		Net Expected				Economic Loss				(Paid)			Net Expected
		Loss to be				Development				Recovered			Loss to be
		Paid (Recovered) as of								Losses(1)			Paid (Recovered) as of
		December 31, 2012											December 31, 2013(2)
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	10			$	16			$	(1	)	$	25
	Alt-A first lien	693				(40		)		(75		)	578
	Option ARM	460				63				(359		)	164
	Subprime	351				101				(30		)	422
	Total first lien	1,514				140				(465		)	1,189
Second lien:
Closed-end second lien	99				(3		)		(9		)	87
HELOCs	39				3				(113		)	(71		)
Total second lien	138				0				(122		)	16
Total U.S. RMBS	1,652				140				(587		)	1,205
TruPS	27				7				17			51
Other structured finance	312				(41		)		(151		)	120
U.S. public finance	7				239				18			264
Non-U.S. public finance	52				17				(12		)	57
Other insurance	(3		)		(10		)		10			(3		)
Total	$	2,047			$	352			$	(705	)	$	1,694
____________________
-1	Net of ceded paid losses, whether or not such amounts have been settled with reinsurers. Ceded paid losses are typically settled 45 days after the end of the reporting period. Such amounts are recorded in reinsurance recoverable on paid losses included in other assets. The Company paid $37 million and $54 million in LAE for the years ended December 31, 2014 and 2013, respectively.
-2	Includes expected LAE to be paid of $16 million as of December 31, 2014 and $34 million as of December 31, 2013.
Net Expected Recoveries from
Breaches of R&W Rollforward
Year Ended December 31, 2014
	Future Net				R&W Development				R&W (Recovered)			Future Net
	R&W Benefit as of				and Accretion of				During 2014			R&W Benefit as of
	December 31, 2013				Discount							December 31, 2014 (1)
					During 2014
	(in millions)
U.S. RMBS:
First lien:
Prime first lien	$	4			$	(1	)		$	(1	)	$	2
Alt-A first lien	274				131				(299		)	106
Option ARM	173				14				(172		)	15
Subprime	118				50				(59		)	109
Total first lien	569				194				(531		)	232
Second lien:
Closed-end second lien	98				(6		)		(7		)	85
HELOC	45				80				(125		)	—
Total second lien	143				74				(132		)	85
Total	$	712			$	268			$	(663	)	$	317
Net Expected Recoveries from
Breaches of R&W Rollforward
Year Ended December 31, 2013
	Future Net				R&W Development				R&W (Recovered) During 2013			Future Net
	R&W Benefit as of				and Accretion of							R&W Benefit as of
	December 31, 2012				Discount							December 31, 2013
					During 2013
	(in millions)
U.S. RMBS:
First lien:
Prime first lien	$	4			$	—			$	—		$	4
Alt-A first lien	378				41				(145		)	274
Option ARM	591				161				(579		)	173
Subprime	109				9				—			118
Total first lien	1,082				211				(724		)	569
Second lien:
Closed-end second lien	138				(9		)		(31		)	98
HELOC	150				94				(199		)	45
Total second lien	288				85				(230		)	143
Total	$	1,370			$	296			$	(954	)	$	712
____________________
-1	See the section "Breaches of Representations and Warranties" below for eligible assets held in trust.
Net Expected Loss to be Paid
After Net Expected Recoveries for Breaches of R&W
Roll Forward by Sector
Year Ended December 31, 2014
	Net Expected				Economic Loss				(Paid)			Net Expected
	Loss to be				Development				Recovered			Loss to be
	Paid (Recovered) as of								Losses(1)			Paid (Recovered) as of
	December 31, 2013											December 31, 2014
	(in millions)
U.S. RMBS:
First lien:
Prime first lien	$	21			$	(16	)		$	(1	)	$	4
Alt-A first lien	304				(144		)		144			304
Option ARM	(9		)		(59		)		52			(16		)
Subprime	304				(7		)		6			303
Total first lien	620				(226		)		201			595
Second lien:
Closed-end second lien	(11		)		3				16			8
HELOCs	(116		)		(45		)		142			(19		)
Total second lien	(127		)		(42		)		158			(11		)
Total U.S. RMBS	493				(268		)		359			584
TruPS	51				(28		)		—			23
Other structured finance	120				96				2			218
U.S. public finance	264				183				(144		)	303
Non-U.S. public finance	57				(12		)		—			45
Other insurance	(3		)		(1		)		—			(4		)
Total	$	982			$	(30	)		$	217		$	1,169
Net Expected Loss to be Paid
After Net Expected Recoveries for Breaches of R&W
Roll Forward by Sector
Year Ended December 31, 2013
	Net Expected				Economic Loss				(Paid)			Net Expected
	Loss to be				Development				Recovered			Loss to be
	Paid (Recovered) as of								Losses(1)			Paid (Recovered) as of
	December 31, 2012											December 31, 2013
	(in millions)
U.S. RMBS:
First lien:
Prime first lien	$	6			$	16			$	(1	)	$	21
Alt-A first lien	315				(81		)		70			304
Option ARM	(131		)		(98		)		220			(9		)
Subprime	242				92				(30		)	304
Total first lien	432				(71		)		259			620
Second lien:
Closed-end second lien	(39		)		6				22			(11		)
HELOCs	(111		)		(91		)		86			(116		)
Total second lien	(150		)		(85		)		108			(127		)
Total U.S. RMBS	282				(156		)		367			493
TruPS	27				7				17			51
Other structured finance	312				(41		)		(151		)	120
U.S. public finance	7				239				18			264
Non-U.S. public finance	52				17				(12		)	57
Other insurance	(3		)		(10		)		10			(3		)
Total	$	677			$	56			$	249		$	982
____________________
-1	Net of ceded paid losses, whether or not such amounts have been settled with reinsurers. Ceded paid losses and recoveries are typically settled 45 days after the end of the reporting period. Such amounts are recorded in reinsurance recoverable on paid losses included in other assets.
The following tables present the present value of net expected loss to be paid for all contracts by accounting model, by sector and after the benefit for estimated and contractual recoveries for breaches of R&W.
Net Expected Loss to be Paid (Recovered)
By Accounting Model
As of December 31, 2014
	Financial				FG VIEs(1)				Credit			Total
	Guaranty								Derivatives(2)
	Insurance
	(in millions)
U.S. RMBS:
First lien:
Prime first lien	$	2			$	—			$	2		$	4
Alt-A first lien	288				17				(1		)	304
Option ARM	(15		)		—				(1		)	(16		)
Subprime	163				71				69			303
Total first lien	438				88				69			595
Second lien:
Closed-end second lien	(27		)		31				4			8
HELOCs	(26		)		7				—			(19		)
Total second lien	(53		)		38				4			(11		)
Total U.S. RMBS	385				126				73			584
TruPS	1				—				22			23
Other structured finance	255				—				(37		)	218
U.S. public finance	303				—				—			303
Non-U.S. public finance	45				—				—			45
Subtotal	$	989			$	126			$	58		1,173
Other												(4		)
Total												$	1,169
Net Expected Loss to be Paid (Recovered)
By Accounting Model
As of December 31, 2013
	Financial				FG VIEs(1)				Credit			Total
	Guaranty								Derivatives(2)
	Insurance
	(in millions)
U.S. RMBS:
First lien:
Prime first lien	$	3			$	—			$	18		$	21
Alt-A first lien	199				31				74			304
Option ARM	(18		)		(2		)		11			(9		)
Subprime	149				81				74			304
Total first lien	333				110				177			620
Second lien:
Closed-end second lien	(34		)		25				(2		)	(11		)
HELOCs	(41		)		(75		)		—			(116		)
Total second lien	(75		)		(50		)		(2		)	(127		)
Total U.S. RMBS	258				60				175			493
TruPS	3				—				48			51
Other structured finance	161				—				(41		)	120
U.S. public finance	264				—				—			264
Non-U.S. public finance	55				—				2			57
Subtotal	$	741			$	60			$	184		985
Other												(3		)
Total												$	982
___________________
(1)    Refer to Note 10, Consolidated Variable Interest Entities.
(2)    Refer to Note 9, Financial Guaranty Contracts Accounted for as Credit Derivatives.
The following tables present the net economic loss development for all contracts by accounting model, by sector and after the benefit for estimated and contractual recoveries for breaches of R&W.
Net Economic Loss Development (Benefit)
By Accounting Model
Year Ended December 31, 2014
	Financial				FG VIEs(1)				Credit			Total
	Guaranty								Derivatives(2)
	Insurance
	(in millions)
U.S. RMBS:
First lien:
Prime first lien	$	—			$	—			$	(16	)	$	(16	)
Alt-A first lien	(87		)		(13		)		(44		)	(144		)
Option ARM	(48		)		1				(12		)	(59		)
Subprime	(15		)		6				2			(7		)
Total first lien	(150		)		(6		)		(70		)	(226		)
Second lien:
Closed-end second lien	(2		)		8				(3		)	3
HELOCs	(128		)		83				—			(45		)
Total second lien	(130		)		91				(3		)	(42		)
Total U.S. RMBS	(280		)		85				(73		)	(268		)
TruPS	(2		)		—				(26		)	(28		)
Other structured finance	97				—				(1		)	96
U.S. public finance	183				—				—			183
Non-U.S. public finance	(10		)		—				(2		)	(12		)
Subtotal	$	(12	)		$	85			$	(102	)	(29		)
Other												(1		)
Total												$	(30	)
Net Economic Loss Development (Benefit)
By Accounting Model
Year Ended December 31, 2013
	Financial				FG VIEs(1)				Credit			Total
	Guaranty								Derivatives(2)
	Insurance
	(in millions)
U.S. RMBS:
First lien:
Prime first lien	$	(1	)		$	—			$	17		$	16
Alt-A first lien	(54		)		5				(32		)	(81		)
Option ARM	(62		)		(36		)		—			(98		)
Subprime	48				32				12			92
Total first lien	(69		)		1				(3		)	(71		)
Second lien:
Closed-end second lien	30				(34		)		10			6
HELOCs	(91		)		(1		)		1			(91		)
Total second lien	(61		)		(35		)		11			(85		)
Total U.S. RMBS	(130		)		(34		)		8			(156		)
TruPS	—				—				7			7
Other structured finance	(36		)		—				(5		)	(41		)
U.S. public finance	239				—				—			239
Non-U.S. public finance	16				—				1			17
Subtotal	$	89			$	(34	)		$	11		66
Other												(10		)
Total												$	56
___________________
(1)    Refer to Note 10, Consolidated Variable Interest Entities.
(2)    Refer to Note 9, Financial Guaranty Contracts Accounted for as Credit Derivatives.
Approach to Projecting Losses in U.S. RMBS
The Company projects losses on its insured U.S. RMBS on a transaction-by-transaction basis by projecting the performance of the underlying pool of mortgages over time and then applying the structural features (i.e., payment priorities and tranching) of the RMBS to the projected performance of the collateral over time. The resulting projected claim payments or reimbursements are then discounted using risk-free rates. For transactions where the Company projects it will receive recoveries from providers of R&W, it projects the amount of recoveries and either establishes a recovery for claims already paid or reduces its projected claim payments accordingly.
The further behind a mortgage borrower falls in making payments, the more likely it is that he or she will default. The rate at which borrowers from a particular delinquency category (number of monthly payments behind) eventually default is referred to as the “liquidation rate.” The Company derives its liquidation rate assumptions from observed roll rates, which are the rates at which loans progress from one delinquency category to the next and eventually to default and liquidation. The Company applies liquidation rates to the mortgage loan collateral in each delinquency category and makes certain timing assumptions to project near-term mortgage collateral defaults from loans that are currently delinquent.
Mortgage borrowers that are not more than one payment behind (generally considered performing borrowers) have demonstrated an ability and willingness to pay throughout the recession and mortgage crisis, and as a result are viewed as less likely to default than delinquent borrowers. Performing borrowers that eventually default will also need to progress through delinquency categories before any defaults occur. The Company projects how many of the currently performing loans will default and when they will default, by first converting the projected near term defaults of delinquent borrowers derived from liquidation rates into a vector of conditional default rates ("CDR"), then projecting how the conditional default rates will develop over time. Loans that are defaulted pursuant to the conditional default rate after the near-term liquidation of currently delinquent loans represent defaults of currently performing loans and projected re-performing loans. A conditional default rate is the outstanding principal amount of defaulted loans liquidated in the current month divided by the remaining outstanding amount of the whole pool of loans (or “collateral pool balance”). The collateral pool balance decreases over time as a result of scheduled principal payments, partial and whole principal prepayments, and defaults.
In order to derive collateral pool losses from the collateral pool defaults it has projected, the Company applies a loss severity. The loss severity is the amount of loss the transaction experiences on a defaulted loan after the application of net proceeds from the disposal of the underlying property. The Company projects loss severities by sector based on its experience to date. The Company continues to update its evaluation of these exposures as new information becomes available.
The Company has been enforcing claims for breaches of R&W regarding the characteristics of the loans included in the collateral pools. The Company calculates a credit for R&W recoveries to include in its cash flow projections. Where the Company has an agreement with an R&W provider (such as its agreements with Bank of America, Deutsche Bank and UBS, which are described in more detail under "Breaches of Representations and Warranties" below), that credit is based on the agreement or potential agreement. Where the Company does not have an agreement with the R&W provider but the Company believes the R&W provider to be economically viable, the Company estimates what portion of its past and projected future claims it believes will be reimbursed by that provider.
The Company projects the overall future cash flow from a collateral pool by adjusting the payment stream from the principal and interest contractually due on the underlying mortgages for the collateral losses it projects as described above; assumed voluntary prepayments; and servicer advances. The Company then applies an individual model of the structure of the transaction to the projected future cash flow from that transaction’s collateral pool to project the Company’s future claims and claim reimbursements for that individual transaction. Finally, the projected claims and reimbursements are discounted using risk-free rates. The Company runs several sets of assumptions regarding mortgage collateral performance, or scenarios, and probability weights them.
The ultimate performance of the Company’s RMBS transactions remains highly uncertain, may differ from the Company's projections and may be subject to considerable volatility due to the influence of many interrelated factors that are difficult to predict, including the level and timing of loan defaults, changes in housing prices, results from the Company’s loss mitigation activities and other variables. The Company will continue to monitor the performance of its RMBS exposures and will adjust its RMBS loss projection assumptions and scenarios based on actual performance and management’s view of future performance. If actual experience differs from the Company’s assumptions, the losses incurred could be materially different from the estimate.
The Company's RMBS loss projection methodology assumes that the housing and mortgage markets will continue improving. Each period the Company makes a judgment as to whether to change the assumptions it uses to make RMBS loss projections based on its observation during the period of the performance of its insured transactions (including early stage delinquencies, late stage delinquencies and loss severity) as well as the residential property market and economy in general, and, to the extent it observes changes, it makes a judgment as whether those changes are normal fluctuations or part of a trend.
Year-End 2014 Compared to Year-End 2013 U.S. RMBS Loss Projections
Based on its observations of the performance of its insured transactions (including early stage delinquencies, late stage delinquencies and loss severity) as well as the residential property market and economy in general, the Company chose to use the same general methodology to project first lien RMBS losses as of December 31, 2014 as it used as of December 31, 2013, but it made a number of refinements to reflect its observations, notably:
•	updated the liquidation rates it uses on delinquent loans based on observations and on an assumption that loan modifications (which improve liquidation rates) would over the next year be less frequent than they were over the most recent year
•	updated the liquidation rate it uses for loans reported as current but that had been reported as modified over the previous twelve months, based on observed data
•	established a liquidation rate assumption for loans reported as current and not modified in the past twelve months but that had been reported as delinquent in the previous twelve months
•	established loss severity assumptions by vintage category as well as product type, rather than just product type as done previously
•	beginning with the third quarter 2014, each quarter shortened by three months the period it is projecting it will take in the base case to reach the final CDR
The methodology and revised assumptions the Company uses to project first lien RMBS losses and the scenarios it employs are described in more detail below under " - U.S. First Lien RMBS Loss Projections: Alt A First Lien, Option ARM, Subprime and Prime". The Company estimated the impact of all of the refinements to its first lien RMBS assumptions described above to be a decrease of expected losses of approximately $42 million (before adjustments for settlements or loss mitigation purchases).
Based on its observations of the performance of its insured transactions (including early stage delinquencies, late stage delinquencies and loss severity) as well as the residential property market and economy in general, the Company chose to use the same general methodology to project second lien RMBS losses as of December 31, 2014 as it used as of December 31, 2013, but it made a number of refinements to reflect its observations, notably with respect to most HELOC projections to:
•	reflect increased recoveries on newly defaulted loans as well as previously defaulted loans
•	project incremental defaults associated with increased monthly payments that occur when interest-only periods end
•	increase the assumed final conditional prepayment rate ("CPR") from 10% to 15%
The net impact of the refinements in the first two bullet points, which were implemented in the third quarter 2014, was an increase of $36 million in expected losses in the Company's base case as of September 30, 2014. The net impact of the refinements in the third bullet point was an increase in $13 million in expected losses in the Company's base case as of December 31, 2014.
The methodology and assumptions the Company uses to project second lien RMBS losses and the scenarios it employs are described in more detail below under " - U.S. Second Lien RMBS Loss Projections: HELOCs and Closed-End Second Lien".
Year-End 2013 Compared to Year-End 2012 U.S. RMBS Loss Projections
Based on the Company's observation during the year of the performance of its insured RMBS transactions (including early stage delinquencies, late stage delinquencies and loss severity) as well as the residential property market and economy in general, the Company chose to use the same general methodology (with the refinements described below) to project RMBS losses as of December 31, 2013 as it used as of December 31, 2012. The Company's use of the same general approach to project RMBS losses as of December 31, 2013 as it used as of December 31, 2012 was consistent with its view at December 31, 2013 that the housing and mortgage market recovery was occurring at a slower pace than it anticipated at December 31, 2012.
The Company refined its first lien RMBS loss projection methodology as of December 31, 2013 to model explicitly the behavior of borrowers with loans that had been modified. The Company has observed that mortgage loan servicers were modifying more mortgage loans (reducing or forbearing from collecting interest or principal or both due on mortgage loans) to reduce the borrowers’ monthly payments and so improve their payment performance than was the case before the mortgage crisis. Borrowers who are current based on their new, reduced monthly payments are generally reported as current, but are more likely to default than borrowers who are current and whose loans have not been modified. The Company believes modified loans are most likely to default again during the first year after modification. The Company set its liquidation rate assumptions as of December 31, 2012 based on observed roll rates and with modification activity in mind. As of December 31, 2013 the Company made a number of refinements to its first lien RMBS loss projection assumptions to treat loan modifications explicitly. Specifically, in the base case approach, it:
•	established a liquidation rate assumption for loans reported as current but that had been reported as modified in the previous 12 months,
•	assumed that currently delinquent loans that did not roll to liquidation would behave like modified loans, and so applied the modified loan liquidation rate to them,
•	increased from two to three years the period over which it calculates the initial CDR based on assumed liquidations of non-performing loans and modified loans, to account for the longer period modified loans will take to default,
•	increased the period it assumes the transactions will experience the initial loss severity assumption before it improves and the period during which the transaction will experience low voluntary prepayment rates,
•	established an assumption for servicers not to advance loan payments on all delinquent loans
The methodology and revised assumptions the Company uses to project first lien RMBS losses and the scenarios it employs are described in more detail below under " - U.S. First Lien RMBS Loss Projections: Alt A First Lien, Option ARM, Subprime and Prime". The refinement in assumptions described above resulted in a reduction of the initial CDRs but the application of the initial CDRs for a longer period, which generally resulted in a higher amount of loans being liquidated at the initial CDR under the refined assumptions than under the initial CDR under the previous assumptions. The Company estimated the impact of all of the refinements to its assumptions described above to be an increase of expected losses of approximately $8 million (before adjustments for settlements or loss mitigation purchases) by running on the first lien RMBS portfolio as of December 31, 2013 base case assumptions similar to what it used as of December 31, 2012 and comparing those results to those results from the refined assumptions.
During 2013 the Company observed improvements in the performance of its second lien RMBS transactions that, when viewed in the context of their performance prior to 2013, suggested those transactions were beginning to respond to the improvements in the residential property market and economy being widely reported by market observers. Based on such observations, in projecting losses for second lien RMBS the Company chose to decrease by two months in its base scenario and by three months in its optimistic scenario the period it assumed it would take the mortgage market to recover as compared to December 31, 2012. Also during 2013 the Company observed material improvements in the delinquency measures of certain second lien RMBS for which the servicing had been transferred, and made certain adjustments on just those transactions to reflect its view that much of this improvement was due to loan modifications and reinstatements made by the new servicer and that such recently modified and reinstated loans may have a higher likelihood of defaulting again. The methodology and assumptions the Company used to project second lien RMBS losses and the scenarios it employed are described in more detail below under " - U.S. Second Lien RMBS Loss Projections: HELOCs and Closed-End Second Lien".
The Company observed some improvement in delinquency trends in most of its RMBS transactions during 2013, with some of that improvement in second liens driven by servicing transfers it effectuated. Such improvement is naturally transmitted to its projections for each individual RMBS transaction, since the projections are based on the delinquency performance of the loans in that individual transaction.
U.S. First Lien RMBS Loss Projections: Alt-A First Lien, Option ARM, Subprime and Prime
The majority of projected losses in first lien RMBS transactions are expected to come from non-performing mortgage loans (those that have been modified or have been delinquent in the previous 12 months, are two or more payments behind, are in foreclosure or that have been foreclosed and so the RMBS issuer owns the underlying real estate). Changes in the amount of non-performing loans from the amount projected in the previous period are one of the primary drivers of loss development in this portfolio. In order to determine the number of defaults resulting from these delinquent and foreclosed loans, the Company applies a liquidation rate assumption to loans in each of various non-performing categories. The Company arrived at its liquidation rates based on data purchased from a third party provider and assumptions about how delays in the foreclosure process and loan modifications may ultimately affect the rate at which loans are liquidated. Each year the Company reviews the most recent twenty-four months of this data and adjusts its liquidation rates based on its observations. The following table shows liquidation assumptions for various non-performing categories.
First Lien Liquidation Rates
	December 31, 2014		December 31, 2013		December 31, 2012
Current Loans Modified in Previous 12 Months
Alt A and Prime	25%		35%		N/A
Option ARM	25		35		N/A
Subprime	25		35		N/A
Current Loans Delinquent in the Previous 12 Months
Alt A and Prime	25		N/A		N/A
Option ARM	25		N/A		N/A
Subprime	25		N/A		N/A
30 – 59 Days Delinquent
Alt A and Prime	35		50		35%
Option ARM	40		50		50
Subprime	35		45		30
60 – 89 Days Delinquent
Alt A and Prime	50		60		55
Option ARM	55		65		65
Subprime	40		50		45
90+ Days Delinquent
Alt A and Prime	60		75		65
Option ARM	65		70		75
Subprime	55		60		60
Bankruptcy
Alt A and Prime	45		60		55
Option ARM	50		60		70
Subprime	40		55		50
Foreclosure
Alt A and Prime	75		85		85
Option ARM	80		80		85
Subprime	70		70		80
Real Estate Owned
All	100		100		100
While the Company uses liquidation rates as described above to project defaults of non-performing loans (including current loans modified or delinquent within the last 12 months), it projects defaults on presently current loans by applying a CDR trend. The start of that CDR trend is based on the defaults the Company projects will emerge from currently nonperforming, recently nonperforming and modified loans. The total amount of expected defaults from the non-performing loans is translated into a constant CDR (i.e., the CDR plateau), which, if applied for each of the next 36 months, would be sufficient to produce approximately the amount of defaults that were calculated to emerge from the various delinquency categories. The CDR thus calculated individually on the delinquent collateral pool for each RMBS is then used as the starting point for the CDR curve used to project defaults of the presently performing loans.
In the base case, after the initial 36-month CDR plateau period, each transaction’s CDR is projected to improve over 12 months to an intermediate CDR (calculated as 20% of its CDR plateau); that intermediate CDR is held constant for 36 months and then trails off in steps to a final CDR of 5% of the CDR plateau. In the base case, the Company assumes the final CDR will be reached eight years and six months after the initial 36-month CDR plateau period, which is six months shorter than assumed as of December 31, 2013 but the same calendar date as it assumed as of June 30, 2014. Under the Company’s methodology, defaults projected to occur in the first 36 months represent defaults that can be attributed to loans that were modified or delinquent in the last 12 months or that are currently delinquent or in foreclosure, while the defaults projected to occur using the projected CDR trend after the first 36 month period represent defaults attributable to borrowers that are currently performing or are projected to reperform.
Another important driver of loss projections is loss severity, which is the amount of loss the transaction incurs on a loan after the application of net proceeds from the disposal of the underlying property. Loss severities experienced in first lien transactions have reached historic high levels, and the Company is assuming in the base case that these high levels generally will continue for another 18 months. The Company determines its initial loss severity based on actual recent experience. The Company then assumes that loss severities begin returning to levels consistent with underwriting assumptions beginning after the initial 18 month period, declining to 40% in the base case over 2.5 years. Beginning for December 31, 2014, the Company differentiated the loss severity assumptions depending on the vintage of the transaction, as shown in the table below.
The following table shows the range as well as the average, weighted by outstanding net insured par, for key assumptions used in the calculation of expected loss to be paid for individual transactions for direct vintage 2004 - 2008 first lien U.S. RMBS.
Key Assumptions in Base Case Expected Loss Estimates
First Lien RMBS(1)
	As of							As of						As of
	31-Dec-14							31-Dec-13						31-Dec-12
	Range					Weighted Average		Range				Weighted Average		Range				Weighted Average
Alt-A First Lien
Plateau CDR	2	%	–	13.40%		7.30%		2.8	%	–	18.40%	9.70%		3.8	%	–	23.20%	13.30%
Intermediate CDR	0.4	%	–	2.70%		1.50%		0.6	%	–	3.70%	1.90%		0.8	%	–	4.60%	2.70%
Period until intermediate CDR	48 months							48 months						36 months
Final CDR	0.1	%	–	0.70%		0.30%		0.1	%	–	0.90%	0.50%		0.2	%	–	1.20%	0.60%
Initial loss severity:
2005 and prior	60%							65%						65%
2006	70%							65%						65%
2007	65%							65%						65%
Initial CPR	1.7	%	–	21.00%		7.70%		0	%	–	34.20%	9.70%		0	%	–	39.40%	7.40%
Final CPR(2)	15%							15%						15%
Option ARM
Plateau CDR	4.3	%	–	14.20%		10.60%		4.9	%	–	16.80%	11.90%		7	%	–	26.10%	18.40%
Intermediate CDR	0.9	%	–	2.80%		2.10%		1	%	–	3.40%	2.40%		1.4	%	–	5.20%	3.70%
Period until intermediate CDR	48 months							48 months						36 months
Final CDR	0.2	%	–	0.70%		0.50%		0.2	%	–	0.80%	0.50%		0.4	%	–	1.30%	0.80%
Initial loss severity:
2005 and prior	60%							65%						65%
2006	70%							65%						65%
2007	65%							65%						65%
Initial CPR	1.1	%	–	11.80%		4.90%		0.4	%	–	13.10%	4.70%		0	%	–	10.70%	4.00%
Final CPR(2)	15%							15%						15%
Subprime
Plateau CDR	4.9	%	–	15.00%		10.60%		5.6	%	–	16.20%	11.80%		7.3	%	–	26.20%	17.30%
Intermediate CDR	1	%	–	3.00%		2.10%		1.1	%	–	3.20%	2.40%		1.5	%	–	5.20%	3.50%
Period until intermediate CDR	48 months							48 months						36 months
Final CDR	0.2	%	–	0.70%		0.40%		0.3	%	–	0.80%	0.40%		0.4	%	–	1.30%	0.60%
Initial loss severity:
2005 and prior	75%							90%						90%
2006	90%							90%						90%
2007	90%							90%						90%
Initial CPR	0	%	–	10.50%		6.10%		0	%	–	15.70%	4.10%		0	%	–	17.60%	3.60%
Final CPR(2)	15%							15%						15%
____________________
(1)                                Represents variables for most heavily weighted scenario (the “base case”).
(2)	For transactions where the initial CPR is higher than the final CPR, the initial CPR is held constant and the final CPR is not used.
The rate at which the principal amount of loans is voluntarily prepaid may impact both the amount of losses projected (since that amount is a function of the conditional default rate, the loss severity and the loan balance over time) as well as the amount of excess spread (the amount by which the interest paid by the borrowers on the underlying loan exceeds the amount of interest owed on the insured obligations). The assumption for the voluntary CPR follows a similar pattern to that of the conditional default rate. The current level of voluntary prepayments is assumed to continue for the plateau period before gradually increasing over 12 months to the final CPR, which is assumed to be 15% in the base case. For transactions where the initial CPR is higher than the final CPR, the initial CPR is held constant and the final CPR is not used. These assumptions are the same as those the Company used for December 31, 2013 and December 31, 2012 except that, as of December 31, 2014 and December 31, 2013 the period of initial CDRs were assumed to last 12 months longer than they were assumed to last as of December 31, 2012, so the initial CPR is also held constant 12 months longer as of December 31, 2014 and December 31, 2013 than it was as of December 31, 2012.
In estimating expected losses, the Company modeled and probability weighted sensitivities for first lien transactions by varying its assumptions of how fast a recovery is expected to occur. One of the variables used to model sensitivities was how quickly the conditional default rate returned to its modeled equilibrium, which was defined as 5% of the initial conditional default rate. The Company also stressed CPR and the speed of recovery of loss severity rates. The Company probability weighted a total of five scenarios (including its base case) as of December 31, 2014. The Company used a similar approach to establish its pessimistic and optimistic scenarios as of December 31, 2014 as it used as of December 31, 2013 and December 31, 2012, increasing and decreasing the periods of stress from those used in the base case, except that all of the stress periods were longer as of December 31, 2014 and December 31, 2013 than they were as of December 31, 2012.
In a somewhat more stressful environment than that of the base case, where the conditional default rate plateau was extended six months (to be 42 months long) before the same more gradual conditional default rate recovery and loss severities were assumed to recover over 4.5 rather than 2.5 years (and subprime loss severities were assumed to recover only to 60% and Option ARM and Alt A loss severities to only 45%), expected loss to be paid would increase from current projections by approximately $29 million for Alt-A first liens, $9 million for Option ARM, $73 million for subprime and $2 million for prime transactions.
In an even more stressful scenario where loss severities were assumed to rise and then recover over nine years and the initial ramp-down of the conditional default rate was assumed to occur over 15 months and other assumptions were the same as the other stress scenario, expected loss to be paid would increase from current projections by approximately $79 million for Alt-A first liens, $21 million for Option ARM, $102 million for subprime and $7 million for prime transactions.
In a scenario with a somewhat less stressful environment than the base case, where conditional default rate recovery was somewhat less gradual, expected loss to be paid would increase from current projections by approximately $0.3 million for Alt-A first lien and would decrease by $12 million for Option ARM, $10 million for subprime and $0.1 million for prime transactions.
In an even less stressful scenario where the conditional default rate plateau was six months shorter (30 months, effectively assuming that liquidation rates would improve) and the conditional default rate recovery was more pronounced, (including an initial ramp-down of the conditional default rate over nine months), expected loss to be paid would decrease from current projections by approximately $28 million for Alt-A first lien, $26 million for Option ARM, $52 million for subprime and $1 million for prime transactions.
U.S. Second Lien RMBS Loss Projections: HELOCs and Closed-End Second Lien
The Company believes the primary variable affecting its expected losses in second lien RMBS transactions is the amount and timing of future losses in the collateral pool supporting the transactions. Expected losses are also a function of the structure of the transaction; the voluntary prepayment rate (typically also referred to as CPR of the collateral); the interest rate environment; and assumptions about the draw rate and loss severity.
The following table shows the range as well as the average, weighted by outstanding net insured par, for key assumptions for the calculation of expected loss to be paid for individual transactions for direct vintage 2004 - 2008 second lien U.S. RMBS.
Key Assumptions in Base Case Expected Loss Estimates
Second Lien RMBS(1)
HELOC key assumptions	As of							As of						As of
	31-Dec-14							31-Dec-13						31-Dec-12
	Range					Weighted Average		Range				Weighted Average		Range				Weighted Average
Plateau CDR	2.8	%	–	6.80%		4.10%		2.3	%	–	7.70%	4.90%		3.8	%	–	15.90%	8.80%
Final CDR trended down to	0.5	%	–	3.20%		1.20%		0.4	%	–	3.20%	1.10%		0.4	%	–	3.20%	1.20%
Period until final CDR	34 months							34 months						36 months
Initial CPR	6.9	%	–	21.80%		11.00%		2.7	%	–	21.50%	9.90%		2.9	%	–	15.40%	6.60%
Final CPR(2)	15	%	–	21.80%		15.50%		10%						10%
Loss severity	90	%	–	98%		90.40%		98%						98%
Closed-end second lien key assumptions	As of							As of						As of
	31-Dec-14							31-Dec-13						31-Dec-12
	Range					Weighted Average		Range				Weighted Average		Range				Weighted Average
Plateau CDR	5.5	%	–	12.50%		7.20%		7.3	%	–	15.10%	8.50%		7.3	%	–	20.70%	12.70%
Final CDR trended down to	3.5	%	–	9.10%		4.90%		3.5	%	–	9.10%	5.00%		3.5	%	–	9.10%	4.90%
Period until final CDR	34 months							34 months						36 months
Initial CPR	2.8	%	–	13.90%		9.90%		3.1	%	–	12.00%	7.10%		1.9	%	–	12.50%	4.00%
Final CPR(2)	15%							10%						10%
Loss severity	98%							98%						98%
____________________
-1	Represents variables for most heavily weighted scenario (the “base case”).
(2)	For transactions where the initial CPR is higher than the final CPR, the initial CPR is held constant and the final CPR is not used.
In second lien transactions the projection of near-term defaults from currently delinquent loans is relatively straightforward because loans in second lien transactions are generally “charged off” (treated as defaulted) by the securitization’s servicer once the loan is 180 days past due. Most second lien transactions report the amount of loans in five monthly delinquency categories (i.e., 30-59 days past due, 60-89 days past due, 90-119 days past due, 120-149 days past due and 150-179 days past due). The Company estimates the amount of loans that will default over the next five months by calculating current representative liquidation rates (the percent of loans in a given delinquency status that are assumed to ultimately default) from selected representative transactions and then applying an average of the preceding twelve months’ liquidation rates to the amount of loans in the delinquency categories. The amount of loans projected to default in the first through fifth months is expressed as a CDR. The first four months’ CDR is calculated by applying the liquidation rates to the current period past due balances (i.e., the 150-179 day balance is liquidated in the first projected month, the 120-149 day balance is liquidated in the second projected month, the 90-119 day balance is liquidated in the third projected month and the 60-89 day balance is liquidated in the fourth projected month). For the fifth month the CDR is calculated using the average 30-59 day past due balances for the prior three months, adjusted as necessary to reflect one-time service events. The fifth month CDR is then used as the basis for the plateau period that follows the embedded five months of losses.
For the base case scenario, the CDR (the “plateau CDR”) was held constant for one month. Once the plateau period has ended, the CDR is assumed to gradually trend down in uniform increments to its final long-term steady state CDR. (The long-term steady state CDR is calculated as the constant CDR that would have yielded the amount of losses originally expected at underwriting.) In the base case scenario, the time over which the CDR trends down to its final CDR is 28 months. Therefore, the total stress period for second lien transactions is 34 months, comprising five months of delinquent data, a one month plateau period and 28 months of decrease to the steady state CDR, the same as of December 31, 2013. This is two months shorter than used for December 31, 2012.
HELOC loans generally permit the borrower to pay only interest for an initial period (often ten years) and, after that period, require the borrower to make both the monthly interest payment and a monthly principal payment, and so increase the borrower's aggregate monthly payment. Some of the HELOC loans underlying the Company's insured HELOC transactions have reached their principal amortization period. Based on the Company’s observation, including information obtained over the last year on the performance of certain loans reaching their principal amortization period and its views of the efficacy of planned servicer intervention, it introduced this year an assumption in the projections for most of its HELOC transactions that 7.5% of loans reaching their amortization periods will default around the time of the payment increase. These projected defaults are in addition to those generated using the CDR curve as described above.
When a second lien loan defaults, there is generally a very low recovery. The Company had assumed as of December 31, 2013 that it will recover only 2% of the collateral defaulting. However, based on additional information the Company obtained over the last year, it increased this recovery assumption in the projections for most of its HELOC transactions as of December 31, 2014 to 10% of collateral defaulting in the future, and also assumed declining additional post-default receipts on previously defaulted collateral.
The rate at which the principal amount of loans is prepaid may impact both the amount of losses projected as well as the amount of excess spread. In the base case, the current CPR (based on experience of the most recent three quarters) is assumed to continue until the end of the plateau before gradually increasing to the final CPR over the same period the CDR decreases. For transactions where the initial CPR is higher than the final CPR, the initial CPR is held constant and the final CPR is not used. The final CPR is assumed to be 15% for both HELOC and closed-end second lien transactions, which is lower than the historical average but reflects the Company’s continued uncertainty about the projected performance of the borrowers in these transactions. This pattern is consistent with how the Company modeled the CPR at December 31, 2013. To the extent that prepayments differ from projected levels it could materially change the Company’s projected excess spread and losses.
The net impact of the three refinements the Company made to projecting expected losses in certain HELOC transactions described above (increased defaults of loans reaching their amortization period, increased recoveries, decreased the redefault rate on modified loans and the increase in the final CPR to 15%) was an increase of approximately $53 million in expected losses in the Company's base case as of December 31, 2014 compared to what it would have been without the refinements. The Company uses a number of other variables in its second lien loss projections, including the spread between relevant interest rate indices and HELOC draw rates (the amount of new advances provided on existing HELOCs expressed as a percentage of the current pool balance). These variables have been relatively stable over the past several quarters and in the relevant ranges have less impact on the projection results than the variables discussed above. However, in a number of HELOC transactions the servicers have been modifying poorly performing loans from floating to fixed rates, and, as a result, rising interest rates would negatively impact the excess spread available from these modified loans to support the transactions.  The Company incorporated these modifications in its assumptions.
In estimating expected losses, the Company modeled and probability weighted three possible CDR curves applicable to the period preceding the return to the long-term steady state CDR using the same approaches and weightings as it did as of December 31, 2013. The Company believes that the level of the elevated CDR and the length of time it will persist is the primary driver behind the likely amount of losses the collateral will suffer. The Company continues to evaluate the assumptions affecting its modeling results.
The Company’s base case assumed a one month CDR plateau and a 28 month ramp-down (for a total stress period of 34 months). The Company also modeled a scenario with a longer period of elevated defaults and another with a shorter period of elevated defaults. Increasing the CDR plateau to four months and increasing the ramp-down by five months to 33-months (for a total stress period of 42 months) would increase the expected loss by approximately $14 million for HELOC transactions and $1 million for closed-end second lien transactions. On the other hand, keeping the CDR plateau at one month but decreasing the length of the CDR ramp-down to 18 months (for a total stress period of 24 months) would decrease the expected loss by approximately $15 million for HELOC transactions and $1 million for closed-end second lien transactions.
Breaches of Representations and Warranties
Generally, when mortgage loans are transferred into a securitization, the loan originator(s) and/or sponsor(s) provide R&W that the loans meet certain characteristics, and a breach of such R&W often requires that the loan be repurchased from the securitization. In many of the transactions the Company insures, it is in a position to enforce these R&W provisions. The Company has pursued breaches of R&W on a loan-by-loan basis or in cases where a provider of R&W refused to honor its repurchase obligations, the Company sometimes chose to initiate litigation. See “Recovery Litigation” below. The Company's success in pursuing these strategies permitted the Company to enter into agreements with R&W providers under which those providers made payments to the Company, agreed to make payments to the Company in the future, and / or repurchased loans from the transactions, all in return for releases of related liability by the Company. In some instances, the entity providing the R&W (or an affiliate of that entity) also benefited from credit protection sold by the Company through a CDS, and the Company entered into an agreement terminating the CDS protection it provided (and so avoiding future losses on that transaction), again in return for releases of related liability by the Company and in certain instances other consideration. Such agreements with R&W providers provide the Company with many of the benefits of pursuing the R&W claims on a loan by loan basis or through litigation, but without the related expense and uncertainty. The Company continues to pursue these strategies against R&W providers with which it does not yet have agreements.
Through December 31, 2014 the Company has caused entities providing R&Ws to pay, or agree to pay, or to terminate insurance protection on future projected losses of, approximately $4.2 billion (gross of reinsurance) in respect of their R&W liabilities for transactions in which the Company has provided insurance.
Based on this success, the Company has included in its net expected loss estimates as of December 31, 2014 an estimated net benefit of $317 million (net of reinsurance). Most of this net benefit is projected to be received pursuant to existing agreements with R&W providers, although some is projected to be received in connection with transactions where the company does not yet have such an agreement. Most of the amount projected to be received pursuant to existing agreements with R&W providers benefits from eligible assets placed in trusts to collateralize the R&W provider’s future reimbursement obligation, with the amount of such collateral subject to increase or decrease from time to time as determined by rating agency requirements. Currently the Company has agreements with three counterparties where a future reimbursement obligation is collateralized by eligible assets held in trust:
•	Bank of America. Under the Company's agreement with Bank of America Corporation and certain of its subsidiaries (“Bank of America”), Bank of America agreed to reimburse the Company for 80% of claims on the first lien transactions covered by the agreement that the Company pays in the future, until the aggregate lifetime collateral losses (not insurance losses or claims) on those transactions reach $6.6 billion. As of December 31, 2014 aggregate lifetime collateral losses on those transactions was $4.1 billion, and the Company was projecting in its base case that such collateral losses would eventually reach $5.1 billion. Bank of America's reimbursement obligation is secured by $574 million of collateral held in trust for the Company's benefit.
•	Deutsche Bank. Under the Company's May 2012 agreement with Deutsche Bank AG and certain of its affiliates (collectively, “Deutsche Bank”), Deutsche Bank agreed to reimburse the Company for certain claims it pays in the future on eight first and second lien transactions, including 80% of claims it pays on those transactions until the aggregate lifetime claims (before reimbursement) reach $319 million. As of December 31, 2014, the Company was projecting in its base case that such aggregate lifetime claims would remain below $319 million. In the event aggregate lifetime claims paid exceed $389 million, Deutsche Bank must reimburse the Company for 85% of such claims paid (in excess of $389 million) until such claims paid reach $600 million.
When the agreement was first signed, Deutsche Bank was also required to reimburse AGC for future claims it pays on certain RMBS resecuritizations. AGC and Deutsche Bank terminated one of the resecuritization transactions on October 10, 2013, another on September 12, 2014 and two more in the fourth quarter of 2014. In the fourth quarter of 2014, AGC and Deutsche Bank also terminated one other BIG transaction under which AGC had provided credit protection to Deutsche Bank through a CDS. In connection with the 2014 terminations, AGC and Deutsche Bank agreed to terminate Deutsche Bank’s reimbursement obligation on all of the RMBS resecuritizations, and AGC made a termination payment to Deutsche Bank and released some of the collateral that had been held in trust. Deutsche Bank remains liable to reimburse the Company for certain claims it pays on eight first and second lien transactions, as described above, and such reimbursement obligation remains secured by $77 million of collateral held in trust for the Company’s benefit.
•	UBS. On May 6, 2013, the Company entered into an agreement with UBS Real Estate Securities Inc. and affiliates ("UBS") and a third party resolving the Company’s claims and liabilities related to specified RMBS transactions that were issued, underwritten or sponsored by UBS and insured by AGM or AGC under financial guaranty insurance policies. Under the agreement, UBS agreed to reimburse the Company for 85% of future losses on three first lien RMBS transactions, and such reimbursement obligation is secured by $109 million of collateral held in trust for the Company's benefit.
For the expected recovery from breaches of R&W in transactions not covered by agreements as of December 31, 2014, the Company did not incorporate any gain contingencies from potential litigation in its estimated repurchases. The amount the Company will ultimately recover related to such contractual R&W is uncertain and subject to a number of factors including the counterparty's ability to pay, the number and loss amount of loans determined to have breached R&W and, potentially, negotiated settlements or litigation recoveries. As such, the Company's estimate of recoveries is uncertain and actual amounts realized may differ significantly from these estimates. In arriving at the expected recovery from breaches of R&W not already covered by agreements, the Company considered the creditworthiness of the provider of the R&W, the number of breaches found on defaulted loans, the success rate in resolving these breaches across those transactions where material repurchases have been made and the potential amount of time until the recovery is realized. The calculation of expected recovery from breaches of such contractual R&W involved a variety of scenarios which ranged from the Company recovering substantially all of the losses it incurred due to violations of R&W to the Company realizing limited recoveries. These scenarios were probability weighted in order to determine the recovery incorporated into the Company's estimate of expected losses. This approach was used for both loans that had already defaulted and those assumed to default in the future. The Company adjusts the calculation of its expected recovery from breaches of R&W based on changing facts and circumstances with respect to each counterparty and transaction.
The Company uses the same RMBS projection scenarios and weightings to project its future R&W benefit as it uses to project RMBS losses on its portfolio. To the extent the Company increases its loss projections, the R&W benefit (whether pursuant to an R&W agreement or not) generally will also increase, subject to the agreement limits and thresholds described above. Similarly, to the extent the Company decreases its loss projections, the R&W benefit (whether pursuant to an R&W agreement or not) generally will also decrease, subject to the agreement limits and thresholds described above.
The number of risks subject to R&W recovery is 29, with related net debt service of $2.1 billion as of December 31, 2014 compared to 42 with net debt service of $5.0 billion as of December 31, 2013. Included in these amounts is net debt service related to transactions not yet subject to an agreement. A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments.
The following table provides a breakdown of the development and accretion amount in the roll forward of estimated recoveries associated with claims for breaches of R&W.
Components of R&W Development
	Year Ended December 31,
	2014				2013
	(in millions)
Inclusion or removal of deals with breaches of R&W during period	$	—			$	6
Change in recovery assumptions as the result of recovery success	31				(6		)
Estimated increase (decrease) in defaults that will result in additional (lower) breaches	(37		)		(8		)
Settlements and anticipated settlements	263				289
Accretion of discount on balance	11				15
Total	$	268			$	296
Trust Preferred Securities Collateralized Debt Obligations
The Company has insured or reinsured $4.3 billion of net par (72% of which is in CDS form) of collateralized debt obligations (“CDOs”) backed by TruPS and similar debt instruments, or “TruPS CDOs.” Of the $4.3 billion, $1.3 billion is rated BIG. The underlying collateral in the TruPS CDOs consists of subordinated debt instruments such as TruPS issued by bank holding companies and similar instruments issued by insurance companies, real estate investment trusts (“REITs”) and other real estate related issuers.
The Company projects losses for TruPS CDOs by projecting the performance of the asset pools across several scenarios (which it weights) and applying the CDO structures to the resulting cash flows. At December 31, 2014, the Company has projected expected losses to be paid for TruPS CDOs of $23 million. During 2014 there was positive economic development of approximately $28 million, which was due primarily to improving collateral performance throughout 2014.
“XXX” Life Insurance Transactions
The Company’s $3.1 billion net par of XXX life insurance transactions as of December 31, 2014 include $598 million rated BIG. The BIG “XXX” life insurance reserve securitizations are based on discrete blocks of individual life insurance business. In each such transaction the monies raised by the sale of the bonds insured by the Company were used to capitalize a special purpose vehicle that provides reinsurance to a life insurer or reinsurer. The monies are invested at inception in accounts managed by third-party investment managers.
The BIG “XXX” life insurance transactions consist of two transactions, notes issued by each of Ballantyne Re p.l.c and Orkney Re II p.l.c. These transactions had material amounts of their assets invested in U.S. RMBS. Based on its analysis of the information currently available, including estimates of future investment performance, and projected credit impairments on the invested assets and performance of the blocks of life insurance business at December 31, 2014, the Company’s projected net expected loss to be paid is $161 million. The economic loss development during 2014 was approximately $93 million, which was due primarily to changes in lapse assumptions on the underlying life insurance policies, modest deterioration in life insurance cash flow projections, and a decrease in the risk free rates used to discount the losses.
Manufactured Housing
The Company insures or reinsures a total of $223 million net par of securities backed by manufactured housing loans, of which $160 million is rated BIG. The Company has expected loss to be paid of $25 million as of December 31, 2014. The economic loss development during 2014 was relatively flat.
Student Loan Transactions
The Company has insured or reinsured $2.5 billion net par of student loan securitizations, of which $1.8 billion was issued by private issuers and classified as asset-backed and $0.7 billion was issued by public authorities and classified as public finance. Of these amounts, $196 million and $101 million, respectively, are rated BIG. The Company is projecting approximately $83 million of net expected loss to be paid in these portfolios. In general, the losses are due to: (i) the poor credit performance of private student loan collateral and high loss severities, or (ii) high interest rates on auction rate securities with respect to which the auctions have failed. The economic loss development during 2014 was approximately $18 million, which was due to a decrease during 2014 in the risk free rates used to discount the losses, and some deterioration in collateral performance during the first six months of 2014.
Selected U.S. Public Finance Transactions
The Company insures general obligation bonds of the Commonwealth of Puerto Rico and various obligations of its related authorities and public corporations aggregating $4.9 billion net par. The Company rates $4.7 billion net par of that amount BIG. For additional information regarding the Company's exposure to general obligations of Commonwealth of Puerto Rico and various obligations of its related authorities and public corporations, please refer to "Exposure to Puerto Rico" in Note 3, Outstanding Exposure.
The Company has net par exposure to the City of Detroit, Michigan of $2.0 billion as of December 31, 2014 to the general obligation and water and sewer utility sectors, as described below (which exposures are now investment grade by virtue of improvements and agreements reached through the bankruptcy process and settlement). In December 2014, the City of Detroit emerged from bankruptcy under Chapter 9 of the U.S. Bankruptcy Code. The City’s proposed plan of adjustment and disclosure statement with the Bankruptcy Court was approved in November 2014.
•	The Company has net par exposure to $1.0 billion of sewer revenue bonds and $878 million of water revenue bonds. The sewer and water systems provide services to areas that extend beyond the city limits, and the bonds are secured by a lien on "special revenues." The Company rates the bonds, which are secured by a lien on "special revenues," BBB. The exposure reflects the City's issuance in September 2014 of new series of sewer and water revenue bonds to finance (i) the purchase of outstanding sewer and water revenue bonds offered and accepted under a tender offer commenced by the City and (ii) the refunding of certain other sewer revenue and revenue refunding bonds, and the Company's insurance of a portion of such issuance. In connection with these transactions, approximately $677 million of the Company's then combined $1.8 billion net par exposure to the sewer and water revenue bonds was purchased in the tender offer or refunded, and the Company insured approximately $841 million gross par of the new sewer and water revenue bonds. Under the City's amended plan of adjustment, the impairment of all outstanding sewer and water revenue bonds (even those not purchased pursuant to the tender offer or refunded) that had been proposed was removed, including those provisions which provided for the impairment of interest rates and call protection on such bonds.
•	The Company has net par exposure of $107 million to Michigan Finance Authority by virtue of a court ordered exchange with all holders of the City’s general obligation bonds which occurred upon emergence from bankruptcy in December 2014.  The Michigan Finance Authority bonds are secured by a pledge of the unlimited tax, full faith, credit and resources of the City and the specific ad valorem taxes approved by the voters solely to pay debt service on the general obligation bonds and additional security in the form of a subordinate statutory lien on, and intercept of, the City’s distributable state aid.
•	The Company no longer has  exposure to the City's Pension Obligation Certificates.   Upon the effective date of the City’s plan of adjustment, a commutation agreement between AG Re and Financial Guaranty Insurance Co. ("FGIC") pursuant to which FGIC commuted all the reinsurance AG Re provided to FGIC with respect to the Pension Obligation Certificates became effective.
On June 28, 2012, the City of Stockton, California filed for bankruptcy protection under Chapter 9 of the U.S. Bankruptcy Code. The Company's net exposure to the City's general fund is $117 million, consisting of pension obligation bonds. The Company also had exposure to lease revenue bonds; as of December 31, 2014, the Company owned all of such bonds and held them in its investment portfolio. On October 3, 2013, the Company reached a settlement with the City regarding the treatment of the bonds insured by the Company in the City's plan of adjustment. Under the terms of the settlement, the Company will continue to receive net revenues from an office building and an option to take title to that building, and will be entitled to certain fixed payments and certain variable payments contingent on the City's revenue growth. On October 30, 2014, the bankruptcy court confirmed the City's plan of adjustment, which includes the terms of such settlement, and the plan became effective on February 25, 2015.
The Company has $336 million of net par exposure to the Louisville Arena Authority. The bond proceeds were used to construct the KFC Yum Center, home to the University of Louisville men's and women's basketball teams. Actual revenues available for Debt Service are well below original projections, and under the Company's internal rating scale, the transaction is BIG.
The Company projects that its total net expected loss across its troubled U.S. public finance credits as of December 31, 2014, which incorporated the likelihood of the outcomes mentioned above, will be $303 million, compared with a net expected loss of $264 million as of December 31, 2013. Economic loss development in 2014 was approximately $183 million, which was primarily attributable to Puerto Rico and Detroit exposures.
Certain Selected European Country Transactions
The Company insures and reinsures credits with sub-sovereign exposure to various Spanish and Portuguese issuers where a Spanish and Portuguese sovereign default may cause the regions also to default. The Company's gross exposure to these Spanish and Portuguese credits is $521 million and $114 million, respectively and exposure net of reinsurance for Spanish and Portuguese credits is $374 million and $102 million, respectively. The Company rates most of these issuers in the BB category due to the financial condition of Spain and Portugal and their dependence on the sovereign. The Company's Hungary exposure is to infrastructure bonds dependent on payments from Hungarian governmental entities and covered mortgage bonds issued by Hungarian banks. The Company's gross exposure to these Hungarian credits is $529 million and its exposure net of reinsurance is $499 million, most of which is rated BIG. The Company estimated net expected losses of $45 million related to these Spanish, Portuguese and Hungarian credits. The positive economic loss development during 2014 was approximately $5 million, which was primarily attributable to the favorable movement in the exchange rates between the US Dollar and both the Euro and Hungarian Forint during the year.
Infrastructure Finance
The Company has insured exposure of approximately $3.0 billion to infrastructure transactions with refinancing risk as to which the Company may need to make claim payments that it did not anticipate paying when the policies were issued. Although the Company may not experience ultimate loss on a particular transaction, the aggregate amount of the claim payments may be substantial and reimbursement may not occur for an extended time, if at all. These transactions generally involve long-term infrastructure projects that were financed by bonds that mature prior to the expiration of the project concession. The Company expected the cash flows from these projects to be sufficient to repay all of the debt over the life of the project concession, but also expected the debt to be refinanced in the market at or prior to its maturity. If the issuer is unable to refinance the debt due to market conditions, the Company may have to pay a claim when the debt matures, and then recover its payment from cash flows produced by the project in the future. The Company generally projects that in most scenarios it will be fully reimbursed for such payments. However, the recovery of the payments is uncertain and may take from 10 to 35 years, depending on the transaction and the performance of the underlying collateral. The Company estimates total claims for the two largest transactions with significant refinancing risk, assuming no refinancing, and based on certain performance assumptions could be $1.8 billion on a gross basis; such claims would be payable from 2017 through 2022.
Recovery Litigation
“XXX” Life Insurance Transactions
In December 2008, AGUK filed an action against J.P. Morgan Investment Management Inc. (“JPMIM”), the investment manager in the Orkney Re II transaction, in the Supreme Court of the State of New York alleging that JPMIM engaged in breaches of fiduciary duty, gross negligence and breaches of contract based upon its handling of the investments of Orkney Re II. After AGUK’s claims were dismissed with prejudice in January 2010, AGUK was successful in its subsequent motions and appeals and, as of December 2011, all of AGUK’s claims for breaches of fiduciary duty, gross negligence and contract were reinstated in full. Separately, at the trial court level, discovery is ongoing.
RMBS Transactions
In November 2014, AGM and its affiliate AGC reached a confidential settlement with DLJ Mortgage Capital, Inc., Credit Suisse First Boston Mortgage Securities Corp. and Credit Suisse Securities (USA) LLC to resolve a lawsuit relating to six first lien U.S. RMBS transactions.  AGM and AGC sought damages for alleged breaches of representations and warranties in respect of the underlying loans in these transactions, and failure to cure or repurchase defective loans identified by AGM and AGC.  On November 25, 2014, the parties filed a joint stipulation discontinuing the lawsuit with prejudice.  However, on November 20, 2014, U.S. Bank National Association, as trustee for the transactions, had filed a motion to intervene as a plaintiff in the lawsuit.  On November 26, 2014, the trustee submitted a letter stating that the joint stipulation is ineffective and that the lawsuit may be discontinued only by court order, and requesting an opportunity to review and potentially oppose the settlement.  The court has yet to rule on the trustee’s motion or the trustee’s letter. AGM believes the trustee’s motion and letter are without merit. In the fourth quarter of 2014, AGM recorded a benefit in connection with the settlement.
Previously, AGM also had sued Deutsche Bank AG affiliates DB Structured Products, Inc. and ACE Securities Corp. on a second lien U.S. RMBS transaction that it had insured. In November 2014, AGM resolved those claims against Deutsche Bank and filed a stipulation with the Supreme Court of the State of New York to dismiss the lawsuit; the court ordered the dismissal of the matter on November 17, 2014.

Financial_Guaranty_Insurance_L

Financial Guaranty Insurance Losses	12 Months Ended
	Dec. 31, 2014
Insurance [Abstract]
Financial Guaranty Insurance Losses	Financial Guaranty Insurance Losses
	Accounting Policies
	Loss and LAE Reserve
	Loss and LAE reserve reported on the balance sheet relates only to direct and assumed reinsurance contracts that are accounted for as insurance, substantially all of which are financial guaranty insurance contracts. The corresponding reserve ceded to reinsurers is reported as reinsurance recoverable on unpaid losses. As discussed in Note 8, Fair Value Measurement, contracts that meet the definition of a derivative, as well as consolidated FG VIE assets and liabilities, are recorded separately at fair value. Any expected losses related to consolidated FG VIEs are eliminated upon consolidation. Any expected losses on credit derivatives are not recorded as loss and LAE reserve on the consolidated balance sheet.
	Under financial guaranty insurance accounting, the sum of unearned premium reserve and loss and LAE reserve represents the Company's stand‑ready obligation. Unearned premium reserve is deferred premium revenue, less claim payments and recoveries received that have not yet been recognized in the statement of operations ("contra-paid"). At contract inception, the entire stand-ready obligation is represented by unearned premium reserve. A loss and LAE reserve for an insurance contract is only recorded when the expected loss to be paid net of contra-paid (“total losses”) exceed the deferred premium revenue, on a contract by contract basis.
	When a claim payment is made on a contract, it first reduces any recorded loss and LAE reserve. To the extent there is no loss and LAE reserve on a contract, which occurs when total losses are less than deferred premium revenue, or to the extent loss and LAE reserve is not sufficient to cover a claim payment, then such claim payment is recorded as “contra-paid,” which reduces the unearned premium reserve. The contra-paid is recognized in the line item “loss and LAE” in the consolidated statement of operations when and for the amount that total losses exceed the remaining deferred premium revenue on the insurance contract. Loss and LAE in the consolidated statement of operations is presented net of cessions to reinsurers.
	Salvage and Subrogation Recoverable
	When the Company becomes entitled to the cash flow from the underlying collateral of an insured credit under salvage and subrogation rights as a result of a claim payment or estimated future claim payment, it reduces the expected loss to be paid on the contract. Such reduction in expected loss to be paid can result in one of the following:
	•	a reduction in the corresponding loss and LAE reserve with a benefit to the income statement,
	•	no entry recorded, if “total loss” is not in excess of deferred premium revenue, or
	•	the recording of a salvage asset with a benefit to the income statement if the transaction is in a net recovery position at the reporting date.
	The Company recognizes the expected recovery of claim payments (including recoveries from settlement with R&W providers) made by an acquired subsidiary prior to the date of acquisition, consistent with its policy for recognizing recoveries on all financial guaranty insurance contracts. To the extent that the estimated amount of recoveries increases or decreases, due to changes in facts and circumstances, including the examination of additional loan files and our experience in recovering loans put back to the originator, the Company would recognize a benefit or expense consistent with how changes in the expected recovery of all other claim payments are recorded. The ceded component of salvage and subrogation recoverable is recorded in the line item reinsurance balances payable.
	Expected Loss to be Expensed
	Expected loss to be expensed represents past or expected future net claim payments that have not yet been expensed. Such amounts will be expensed in future periods as deferred premium revenue amortizes into income on financial guaranty insurance policies. Expected loss to be expensed is the Company's projection of incurred losses that will be recognized in future periods, excluding accretion of discount.
	Insurance Contracts' Loss Information
	The following table provides balance sheet information on loss and LAE reserves and salvage and subrogation recoverable, net of reinsurance. The Company used weighted average risk-free rates for U.S. dollar denominated financial guaranty insurance obligations that ranged from 0.0% to 2.95% as of December 31, 2014 and 0.0% to 4.44% as of December 31, 2013. Financial guaranty insurance expected LAE reserve was $12 million as of December 31, 2014 and $27 million as of December 31, 2013.
	Loss and LAE Reserve and Salvage and Subrogation Recoverable
	Net of Reinsurance
	Insurance Contracts
		As of December 31, 2014									As of December 31, 2013
		Loss and			Salvage and			Net Reserve (Recoverable)			Loss and			Salvage and			Net Reserve (Recoverable)
		LAE			Subrogation						LAE			Subrogation
		Reserve, net			Recoverable, net						Reserve, net			Recoverable, net
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	2		$	—		$	2		$	3		$	—		$	3
	Alt-A first lien	87			—			87			108			—			108
	Option ARM	28			40			(12		)	22			47			(25		)
	Subprime	166			8			158			143			2			141
	First lien	283			48			235			276			49			227
	Second lien:
	Closed-end second lien	4			39			(35		)	5			45			(40		)
	HELOC	3			39			(36		)	5			127			(122		)
	Second lien	7			78			(71		)	10			172			(162		)
	Total U.S. RMBS	290			126			164			286			221			65
	TruPS	0			—			0			2			—			2
	Other structured finance	236			2			234			145			6			139
	U.S. public finance	243			8			235			189			8			181
	Non-U.S. public finance	30			—			30			35			—			35
	Financial guaranty	799			136			663			657			235			422
	Other recoverables	—			13			(13		)	—			15			(15		)
	Subtotal	799			149			650			657			250			407
	Effect of consolidating FG VIEs	(80		)	(1		)	(79		)	(103		)	(85		)	(18		)
	Subtotal	719			148			571			554			165			389
	Other	2			6			(4		)	2			5			(3		)
	Total (1)	$	721		$	154		$	567		$	556		$	170		$	386
	____________________
	(1)                                 See “Components of Net Reserves (Salvage)” table for loss and LAE reserve and salvage and subrogation recoverable components.
	The following table reconciles the reported gross and ceded reserve and salvage and subrogation amount to the financial guaranty net reserves (salvage) in the financial guaranty BIG transaction loss summary tables.
	Components of Net Reserves (Salvage)
	Insurance Contracts
		As of			As of
		31-Dec-14			31-Dec-13
		(in millions)
	Loss and LAE reserve	$	799		$	592
	Reinsurance recoverable on unpaid losses	(78		)	(36		)
	Loss and LAE reserve, net	721			556
	Salvage and subrogation recoverable	(151		)	(174		)
	Salvage and subrogation payable(1)	10			19
	Other recoverables(2)	(13		)	(15		)
	Salvage and subrogation recoverable, net and other recoverable	(154		)	(170		)
	Subtotal	567			386
	Less: other (non-financial guaranty business)	(4		)	(3		)
Net reserves (salvage) - financial guaranty	$	571		$	389
____________________
(1)          Recorded as a component of reinsurance balances payable.
(2)     R&W recoverables recorded in other assets on the consolidated balance sheet.
Balance Sheet Classification of
Net Expected Recoveries for Breaches of R&W
Insurance Contracts
	As of December 31, 2014									As of December 31, 2013
	For all			Effect of			Reported on			For all			Effect of			Reported on
	Financial			Consolidating			Balance Sheet(1)			Financial			Consolidating			Balance Sheet(1)
	Guaranty			FG VIEs						Guaranty			FG VIEs
	Insurance									Insurance
	Contracts									Contracts
	(in millions)
Salvage and subrogation recoverable, net	$	20		$	—		$	20		$	122		$	(49	)	$	73
Loss and LAE reserve, net	185			(8		)	177			363			(24		)	339
____________________
-1	The remaining benefit for R&W is either recorded at fair value in FG VIE assets, or not recorded on the balance sheet until the total loss, net of R&W, exceeds unearned premium reserve.
The table below provides a reconciliation of net expected loss to be paid to net expected loss to be expensed. Expected loss to be paid differs from expected loss to be expensed due to: (1) the contra-paid which represent the claim payments made and recoveries received that have not yet been recognized in the statement of operations, (2) salvage and subrogation recoverable for transactions that are in a net recovery position where the Company has not yet received recoveries on claims previously paid (having the effect of reducing net expected loss to be paid by the amount of the previously paid claim and the expected recovery), but will have no future income effect (because the previously paid claims and the corresponding recovery of those claims will offset in income in future periods), and (3) loss reserves that have already been established (and therefore expensed but not yet paid).
Reconciliation of Net Expected Loss to be Paid and
Net Expected Loss to be Expensed
Financial Guaranty Insurance Contracts
	As of December 31, 2014
	(in millions)
Net expected loss to be paid	$	1,115
Less: net expected loss to be paid for FG VIEs	126
Total	989
Contra-paid, net	(100		)
Salvage and subrogation recoverable, net of reinsurance	135
Loss and LAE reserve, net of reinsurance	(719		)
Other recoveries (1)	13
Net expected loss to be expensed (present value)(2)	$	318
____________________
-1	R&W recoverables recorded in other assets on the consolidated balance sheet.
-2	Excludes $89 million as of December 31, 2014 related to consolidated FG VIEs.
The following table provides a schedule of the expected timing of net expected losses to be expensed. The amount and timing of actual loss and LAE may differ from the estimates shown below due to factors such as refundings, accelerations, commutations, changes in expected lives and updates to loss estimates. This table excludes amounts related to FG VIEs, which are eliminated in consolidation.
Net Expected Loss to be Expensed
Financial Guaranty Insurance Contracts
	As of December 31, 2014
	(in millions)
2015 (January 1 – March 31)	$	8
2015 (April 1 – June 30)	8
2015 (July 1 – September 30)	8
2015 (October 1 – December 31)	9
Subtotal 2015	33
2016	34
2017	27
2018	24
2019	22
2020-2024	79
2025-2029	46
2030-2034	32
After 2034	21
Net expected loss to be expensed	318
Discount	413
Total future value	$	731
The following table presents the loss and LAE recorded in the consolidated statements of operations by sector for insurance contracts. Amounts presented are net of reinsurance.
Loss and LAE
Reported on the
Consolidated Statements of Operations
	Year Ended December 31,
	2014			2013			2012
	(in millions)
Structured Finance:
U.S. RMBS:
First lien:
Prime first lien	$	(1	)	$	1		$	2
Alt-A first lien	(66		)	(2		)	51
Option ARM	(37		)	(48		)	137
Subprime	8			80			38
First lien	(96		)	31			228
Second lien:
Closed-end second lien	(2		)	18			31
HELOC	(31		)	(53		)	49
Second lien	(33		)	(35		)	80
Total U.S. RMBS	(129		)	(4		)	308
TruPS	(1		)	(1		)	(10		)
Other structured finance	96			(34		)	3
Structured finance	(34		)	(39		)	301
Public Finance:
U.S. public finance	192			198			51
Non-U.S. public finance	(1		)	16			234
Public finance	191			214			285
Subtotal	157			175			586
Other	(1		)	—			(17		)
Loss and LAE on insurance contracts before FG VIE consolidation	156			175			569
Effect of consolidating FG VIEs	(30		)	(21		)	(65		)
Loss and LAE	$	126		$	154		$	504
The following table provides information on financial guaranty insurance contracts categorized as BIG.
Financial Guaranty Insurance
BIG Transaction Loss Summary
As of December 31, 2014
	BIG Categories
	BIG 1						BIG 2						BIG 3						Total			Effect of			Total
																			BIG, Net			Consolidating
	Gross			Ceded			Gross			Ceded			Gross			Ceded						FG VIEs
	(dollars in millions)
Number of risks(1)	164			(59		)	75			(15		)	119			(38		)	358			—			358
Remaining weighted-average contract period (in years)	9.9			7.4			10.1			8.9			9.6			6.9			10.3			—			10.3
Outstanding exposure:
Principal	$	12,358		$	(2,163	)	$	2,421		$	(286	)	$	3,067		$	(175	)	$	15,222		$	—		$	15,222
Interest	6,350			(838		)	1,274			(121		)	1,034			(48		)	7,651			—			7,651
Total(2)	$	18,708		$	(3,001	)	$	3,695		$	(407	)	$	4,101		$	(223	)	$	22,873		$	—		$	22,873
Expected cash outflows (inflows)	$	1,762		$	(626	)	$	763		$	(77	)	$	1,716		$	(75	)	$	3,463		$	(345	)	$	3,118
Potential recoveries
Undiscounted R&W	(39		)	0			(48		)	2			(171		)	9			(247		)	8			(239		)
Other(3)	(1,687		)	608			(206		)	5			(404		)	30			(1,654		)	177			(1,477		)
Total potential recoveries	(1,726		)	608			(254		)	7			(575		)	39			(1,901		)	185			(1,716		)
Subtotal	36			(18		)	509			(70		)	1,141			(36		)	1,562			(160		)	1,402
Discount	3			0			(117		)	11			(353		)	9			(447		)	34			(413		)
Present value of expected cash flows	$	39		$	(18	)	$	392		$	(59	)	$	788		$	(27	)	$	1,115		$	(126	)	$	989
Deferred premium revenue	$	378		$	(70	)	$	119		$	(6	)	$	312		$	(33	)	$	700		$	(116	)	$	584
Reserves (salvage)(4)	$	(42	)	$	(5	)	$	278		$	(53	)	$	482		$	(10	)	$	650		$	(79	)	$	571
Financial Guaranty Insurance
BIG Transaction Loss Summary
As of December 31, 2013
	BIG Categories
	BIG 1						BIG 2						BIG 3						Total			Effect of			Total
																			BIG, Net			Consolidating
	Gross			Ceded			Gross			Ceded			Gross			Ceded						FG VIEs
	(dollars in millions)
Number of risks(1)	185			(72		)	80			(24		)	119			(34		)	384			—			384
Remaining weighted-average contract period (in years)	10.5			8.1			8.3			5.9			9.8			7.2			10.5			—			10.5
Outstanding exposure:
Principal	$	15,132		$	(2,741	)	$	2,483		$	(160	)	$	3,189		$	(158	)	$	17,745		$	—		$	17,745
Interest	8,114			(1,144		)	1,181			(53		)	1,244			(52		)	9,290			—			9,290
Total(2)	$	23,246		$	(3,885	)	$	3,664		$	(213	)	$	4,433		$	(210	)	$	27,035		$	—		$	27,035
Expected cash outflows (inflows)	$	1,853		$	(528	)	$	1,038		$	(40	)	$	1,681		$	(62	)	$	3,942		$	(690	)	$	3,252
Potential recoveries
Undiscounted R&W	(105		)	1			(201		)	8			(356		)	13			(640		)	72			(568		)
Other(3)	(1,774		)	513			(470		)	19			(351		)	19			(2,044		)	507			(1,537		)
Total potential recoveries	(1,879		)	514			(671		)	27			(707		)	32			(2,684		)	579			(2,105		)
Subtotal	(26		)	(14		)	367			(13		)	974			(30		)	1,258			(111		)	1,147
Discount	13			—			(126		)	3			(352		)	5			(457		)	51			(406		)
Present value of expected cash flows	$	(13	)	$	(14	)	$	241		$	(10	)	$	622		$	(25	)	$	801		$	(60	)	$	741
Deferred premium revenue	$	517		$	(90	)	$	163		$	(7	)	$	303		$	(27	)	$	859		$	(178	)	$	681
Reserves (salvage)(4)	$	(114	)	$	1		$	117		$	(4	)	$	420		$	(13	)	$	407		$	(18	)	$	389
____________________
-1	A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments. The ceded number of risks represents the number of risks for which the Company ceded a portion of its exposure.
-2	Includes BIG amounts related to FG VIEs.
-3	Includes excess spread and draws on HELOCs.
-4	See table “Components of net reserves (salvage).”
Ratings Impact on Financial Guaranty Business
A downgrade of one of the Company’s insurance subsidiaries may result in increased claims under financial guaranties issued by the Company, if the insured obligors were unable to pay.
For example, AGM has issued financial guaranty insurance policies in respect of the obligations of municipal obligors under interest rate swaps. Under the swaps, AGM insures periodic payments owed by the municipal obligors to the bank counterparties. Under certain of the swaps, AGM also insures termination payments that may be owed by the municipal obligors to the bank counterparties. If (i) AGM has been downgraded below the rating trigger set forth in a swap under which it has insured the termination payment, which rating trigger varies on a transaction by transaction basis; (ii) the municipal obligor has the right to cure by, but has failed in, posting collateral, replacing AGM or otherwise curing the downgrade of AGM; (iii) the transaction documents include as a condition that an event of default or termination event with respect to the municipal obligor has occurred, such as the rating of the municipal obligor being downgraded past a specified level, and such condition has been met; (iv) the bank counterparty has elected to terminate the swap; (v) a termination payment is payable by the municipal obligor; and (vi) the municipal obligor has failed to make the termination payment payable by it, then AGM would be required to pay the termination payment due by the municipal obligor, in an amount not to exceed the policy limit set forth in the financial guaranty insurance policy. At AGM's current financial strength ratings, if the conditions giving rise to the obligation of AGM to make a termination payment under the swap termination policies were all satisfied, then AGM could pay claims in an amount not exceeding approximately $146 million in respect of such termination payments. Taking into consideration whether the rating of the municipal obligor is below any applicable specified trigger, if the financial strength ratings of AGM were further downgraded below "A" by S&P or below "A2" by Moody's, and the conditions giving rise to the obligation of AGM to make a payment under the swap policies were all satisfied, then AGM could pay claims in an additional amount not exceeding approximately $393 million in respect of such termination payments.
As another example, with respect to variable rate demand obligations ("VRDOs") for which a bank has agreed to provide a liquidity facility, a downgrade of AGM or AGC may provide the bank with the right to give notice to bondholders that the bank will terminate the liquidity facility, causing the bondholders to tender their bonds to the bank. Bonds held by the bank accrue interest at a “bank bond rate” that is higher than the rate otherwise borne by the bond (typically the prime rate plus 2.00% — 3.00%, and capped at the lesser of 25% and the maximum legal limit). In the event the bank holds such bonds for longer than a specified period of time, usually 90-180 days, the bank has the right to demand accelerated repayment of bond principal, usually through payment of equal installments over a period of not less than five years. In the event that a municipal obligor is unable to pay interest accruing at the bank bond rate or to pay principal during the shortened amortization period, a claim could be submitted to AGM or AGC under its financial guaranty policy. As of December 31, 2014, AGM and AGC had insured approximately $6.0 billion net par of VRDOs, of which approximately $0.3 billion of net par constituted VRDOs issued by municipal obligors rated BBB- or lower pursuant to the Company’s internal rating. The specific terms relating to the rating levels that trigger the bank’s termination right, and whether it is triggered by a downgrade by one rating agency or a downgrade by all rating agencies then rating the insurer, vary depending on the transaction.
In addition, AGM may be required to pay claims in respect of AGMH’s former financial products business if Dexia SA and its affiliates, from which the Company had purchased AGMH and its subsidiaries, do not comply with their obligations following a downgrade of the financial strength rating of AGM. Most of the guaranteed investment contracts ("GICs") insured by AGM allow the GIC holder to terminate the GIC and withdraw the funds in the event of a downgrade of AGM below A3 or A-, with no right of the GIC issuer to avoid such withdrawal by posting collateral or otherwise enhancing its credit. Each GIC contract stipulates the thresholds below which the GIC issuer must post eligible collateral, along with the types of securities eligible for posting and the collateralization percentage applicable to each security type. These collateralization percentages range from 100% of the GIC balance for cash posted as collateral to, typically, 108% for asset-backed securities. If the entire aggregate accreted GIC balance of approximately $2.3 billion as of December 31, 2014 were terminated, the assets of the GIC issuers (which had an aggregate accreted principal of approximately $3.4 billion and an aggregate market value of approximately $3.1 billion) would be sufficient to fund the withdrawal of the GIC funds.

Fair_Value_Measurement

Fair Value Measurement	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurement
	The Company carries a significant portion of its assets and liabilities at fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (i.e., exit price). The price represents the price available in the principal market for the asset or liability. If there is no principal market, then the price is based on a hypothetical market that maximizes the value received for an asset or minimizes the amount paid for a liability (i.e., the most advantageous market).
	Fair value is based on quoted market prices, where available. If listed prices or quotes are not available, fair value is based on either internally developed models that primarily use, as inputs, market-based or independently sourced market parameters, including but not limited to yield curves, interest rates and debt prices or with the assistance of an independent third-party using a discounted cash flow approach and the third party’s proprietary pricing models. In addition to market information, models also incorporate transaction details, such as maturity of the instrument and contractual features designed to reduce the Company’s credit exposure, such as collateral rights as applicable.
	Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. These adjustments include amounts to reflect counterparty credit quality, the Company’s creditworthiness and constraints on liquidity. As markets and products develop and the pricing for certain products becomes more or less transparent, the Company may refine its methodologies and assumptions. During 2014, no changes were made to the Company’s valuation models that had or are expected to have, a material impact on the Company’s consolidated balance sheets or statements of operations and comprehensive income.
	The Company’s methods for calculating fair value produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. The use of different methodologies or assumptions to determine fair value of certain financial instruments could result in a different estimate of fair value at the reporting date.
	The fair value hierarchy is determined based on whether the inputs to valuation techniques used to measure fair value are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect Company estimates of market assumptions. The fair value hierarchy prioritizes model inputs into three broad levels as follows, with Level 1 being the highest and Level 3 the lowest. An asset or liability’s categorization within the fair value hierarchy is based on the lowest level of significant input to its valuation.
	Level 1—Quoted prices for identical instruments in active markets. The Company generally defines an active market as a market in which trading occurs at significant volumes. Active markets generally are more liquid and have a lower bid-ask spread than an inactive market.
	Level 2—Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and observable inputs other than quoted prices, such as interest rates or yield curves and other inputs derived from or corroborated by observable market inputs.
	Level 3—Model derived valuations in which one or more significant inputs or significant value drivers are unobservable. Financial instruments are considered Level 3 when their values are determined using pricing models, discounted cash flow methodologies or similar techniques and at least one significant model assumption or input is unobservable. Level 3 financial instruments also include those for which the determination of fair value requires significant management judgment or estimation.
	Transfers between Levels 1, 2 and 3 are recognized at the end of the period when the transfer occurs. The Company reviews the classification between Levels 1, 2 and 3 quarterly to determine whether a transfer is necessary. During the periods presented, there were no transfers between Level 1, 2 and 3.
	Measured and Carried at Fair Value
	Fixed-Maturity Securities and Short-Term Investments
	The fair value of bonds in the investment portfolio is generally based on prices received from third party pricing services or alternative pricing sources with reasonable levels of price transparency. The pricing services prepare estimates of fair value measurements using their pricing models, which include available relevant market information, benchmark curves, benchmarking of like securities, and sector groupings. Additional valuation factors that can be taken into account are nominal spreads and liquidity adjustments. The pricing services evaluate each asset class based on relevant market and credit information, perceived market movements, and sector news. The market inputs used in the pricing evaluation include: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, reference data and industry and economic events. Benchmark yields have in many cases taken priority over reported trades for securities that trade less frequently or those that are distressed trades, and therefore may not be indicative of the market. The extent of the use of each input is dependent on the asset class and the market conditions. Given the asset class, the priority of the use of inputs may change or some market inputs may not be relevant. Additionally, the valuation of fixed-maturity investments is more subjective when markets are less liquid due to the lack of market based inputs, which may increase the potential that the estimated fair value of an investment is not reflective of the price at which an actual transaction would occur.
	Short-term investments, that are traded in active markets, are classified within Level 1 in the fair value hierarchy and are based on quoted market prices. Securities such as discount notes are classified within Level 2 because these securities are typically not actively traded due to their approaching maturity and, as such, their cost approximates fair value.
	Prices determined based on models where at least one significant model assumption or input is unobservable, are considered to be Level 3 in the fair value hierarchy. As of December 31, 2014, the Company used models to price 37 fixed-maturity securities, which was 7% or $770 million of the Company’s fixed-maturity securities and short-term investments at fair value. Certain Level 3 securities were priced with the assistance of an independent third-party. The pricing is based on a discounted cash flow approach using the third-party’s proprietary pricing models. The models use inputs such as projected prepayment speeds;  severity assumptions; recovery lag assumptions; estimated default rates (determined on the basis of an analysis of collateral attributes, historical collateral performance, borrower profiles and other features relevant to the evaluation of collateral credit quality); home price depreciation/appreciation rates based on macroeconomic forecasts and recent trading activity. The yield used to discount the projected cash flows is determined by reviewing various attributes of the bond including collateral type, weighted average life, sensitivity to losses, vintage, and convexity, in conjunction with market data on comparable securities. Significant changes to any of these inputs could materially change the expected timing of cash flows within these securities which is a significant factor in determining the fair value of the securities.
	Other Invested Assets
	As of December 31, 2014, other invested assets include investments carried and measured at fair value on a recurring basis of $95 million and include primarily investments in the global property catastrophe risk market and investment in a high yield fund that invests primarily in senior loans and bonds. Both of these investments were classified as Level 3. As of December 31, 2013, other invested assets included investments carried and measured at fair value on a recurring basis of $121 million and included primarily certain short-term investments and fixed-maturity securities classified as trading carried as Level 2.
	Other Assets
	Committed Capital Securities
	The fair value of committed capital securities ("CCS"), which is recorded in “other assets” on the consolidated balance sheets, represents the difference between the present value of remaining expected put option premium payments under AGC’s CCS (the “AGC CCS”) and AGM’s Committed Preferred Trust Securities (the “AGM CPS”) agreements, and the estimated present value that the Company would hypothetically have to pay currently for a comparable security (see Note 17, Long Term Debt and Credit Facilities). The AGC CCS and AGM CPS are carried at fair value with changes in fair value recorded on the consolidated statement of operations. The estimated current cost of the Company’s CCS is based on several factors, including broker-dealer quotes for the outstanding securities, the U.S. dollar forward swap curve, London Interbank Offered Rate ("LIBOR") curve projections and the term the securities are estimated to remain outstanding.
	Supplemental Executive Retirement Plans
	The Company classifies the fair value measurement of the assets of the Company's various supplemental executive retirement plans as either Level 1 or Level 2. The fair value of these assets is valued based on the observable published daily values of the underlying mutual fund included in the aforementioned plans (Level 1) or based upon the net asset value of the funds if a published daily value is not available (Level 2). The net asset values are based on observable information.
	Financial Guaranty Contracts Accounted for as Credit Derivatives
	The Company’s credit derivatives consist primarily of insured CDS contracts, and also include interest rate swaps that fall under derivative accounting standards requiring fair value accounting through the statement of operations. The Company does not enter into CDS with the intent to trade these contracts and the Company may not unilaterally terminate a CDS contract absent an event of default or termination event that entitles the Company to terminate; however, the Company has mutually agreed with various counterparties to terminate certain CDS transactions. Such terminations generally are not completed at fair value but instead for an amount that approximates the present value of future premiums or for an amount negotiated as part of an R&W settlement.
	The terms of the Company’s CDS contracts differ from more standardized credit derivative contracts sold by companies outside the financial guaranty industry. The non-standard terms include the absence of collateral support agreements or immediate settlement provisions. In addition, the Company employs relatively high attachment points and does not exit derivatives it sells or purchases for credit protection purposes, except under specific circumstances such as mutual agreements with counterparties. Management considers the non-standard terms of its credit derivative contracts in determining the fair value of these contracts.
	Due to the lack of quoted prices and other observable inputs for its instruments or for similar instruments, the Company determines the fair value of its credit derivative contracts primarily through internally developed, proprietary models that use both observable and unobservable market data inputs to derive an estimate of the fair value of the Company's contracts in its principal markets (see "Assumptions and Inputs"). There is no established market where financial guaranty insured credit derivatives are actively traded, therefore, management has determined that the exit market for the Company’s credit derivatives is a hypothetical one based on its entry market. Management has tracked the historical pricing of the Company’s deals to establish historical price points in the hypothetical market that are used in the fair value calculation. These contracts are classified as Level 3 in the fair value hierarchy since there is reliance on at least one unobservable input deemed significant to the valuation model, most importantly the Company’s estimate of the value of the non-standard terms and conditions of its credit derivative contracts and of the Company’s current credit standing.
	The Company’s models and the related assumptions are continuously reevaluated by management and enhanced, as appropriate, based upon improvements in modeling techniques and availability of more timely and relevant market information.
	The fair value of the Company’s credit derivative contracts represents the difference between the present value of remaining premiums the Company expects to receive or pay and the estimated present value of premiums that a financial guarantor of comparable credit-worthiness would hypothetically charge or pay at the reporting date for the same protection. The fair value of the Company’s credit derivatives depends on a number of factors, including notional amount of the contract, expected term, credit spreads, changes in interest rates, the credit ratings of referenced entities, the Company’s own credit risk and remaining contractual cash flows. The expected remaining contractual premium cash flows are the most readily observable inputs since they are based on the CDS contractual terms. Credit spreads capture the effect of recovery rates and performance of underlying assets of these contracts, among other factors. Consistent with previous years, market conditions at December 31, 2014 were such that market prices of the Company’s CDS contracts were not available.
	Management considers factors such as current prices charged for similar agreements, when available, performance of underlying assets, life of the instrument, and the nature and extent of activity in the financial guaranty credit derivative marketplace. The assumptions that management uses to determine the fair value may change in the future due to market conditions. Due to the inherent uncertainties of the assumptions used in the valuation models, actual experience may differ from the estimates reflected in the Company’s consolidated financial statements and the differences may be material.
	Assumptions and Inputs
	The various inputs and assumptions that are key to the establishment of the Company’s fair value for CDS contracts are as follows:
	•	Gross spread.
	•	The allocation of gross spread among:
	◦	the profit the originator, usually an investment bank, realizes for putting the deal together and funding the transaction (“bank profit”);
	◦	premiums paid to the Company for the Company’s credit protection provided (“net spread”); and
	◦	the cost of CDS protection purchased by the originator to hedge their counterparty credit risk exposure to the Company (“hedge cost”).
	•	The weighted average life which is based on Debt Service schedules.
	The rates used to discount future expected premium cash flows ranged from 0.26% to 2.70% at December 31, 2014 and 0.21% to 3.88% at December 31, 2013.
	The Company obtains gross spreads on its outstanding contracts from market data sources published by third parties (e.g., dealer spread tables for the collateral similar to assets within the Company’s transactions), as well as collateral-specific spreads provided by trustees or obtained from market sources. If observable market credit spreads are not available or reliable for the underlying reference obligations, then market indices are used that most closely resemble the underlying reference obligations, considering asset class, credit quality rating and maturity of the underlying reference obligations. These indices are adjusted to reflect the non-standard terms of the Company’s CDS contracts. Market sources determine credit spreads by reviewing new issuance pricing for specific asset classes and receiving price quotes from their trading desks for the specific asset in question. Management validates these quotes by cross-referencing quotes received from one market source against quotes received from another market source to ensure reasonableness. In addition, the Company compares the relative change in price quotes received from one quarter to another, with the relative change experienced by published market indices for a specific asset class. Collateral specific spreads obtained from third-party, independent market sources are un-published spread quotes from market participants or market traders who are not trustees. Management obtains this information as the result of direct communication with these sources as part of the valuation process.
	With respect to CDS transactions for which there is an expected claim payment within the next twelve months, the allocation of gross spread reflects a higher allocation to the cost of credit rather than the bank profit component. In the current market, it is assumed that a bank would be willing to accept a lower profit on distressed transactions in order to remove these transactions from its financial statements.
	The following spread hierarchy is utilized in determining which source of gross spread to use, with the rule being to use CDS spreads where available. If not available, CDS spreads are either interpolated or extrapolated based on similar transactions or market indices.
	•	Actual collateral specific credit spreads (if up-to-date and reliable market-based spreads are available).
	•	Deals priced or closed during a specific quarter within a specific asset class and specific rating. There were no deals closed during the period presented.
	•	Credit spreads interpolated based upon market indices.
	•	Credit spreads provided by the counterparty of the CDS.
	•	Credit spreads extrapolated based upon transactions of similar asset classes, similar ratings, and similar time to maturity.
	Information by Credit Spread Type (1)
		As of			As of
		31-Dec-14			31-Dec-13
	Based on actual collateral specific spreads	9	%		6	%
	Based on market indices	82	%		88	%
	Provided by the CDS counterparty	9	%		6	%
	Total	100	%		100	%
	____________________
	(1)    Based on par.
	Over time the data inputs can change as new sources become available or existing sources are discontinued or are no longer considered to be the most appropriate. In the fourth quarter of 2014, new market indices were published on Option ARM and Alt-A first lien securitizations. As part of the Company’s normal review process the Company reviewed these indices and based upon the collateral make-up, collateral vintage, and collateral loss experience, determined it to be a better market indication for the Company’s Option ARM and Alt-A first lien securitizations. It is the Company’s objective to move to higher levels on the hierarchy whenever possible, but it is sometimes necessary to move to lower priority inputs because of discontinued data sources or management’s assessment that the higher priority inputs are no longer considered to be representative of market spreads for a given type of collateral. This can happen, for example, if transaction volume changes such that a previously used spread index is no longer viewed as being reflective of current market levels.
	The Company interpolates a curve based on the historical relationship between the premium the Company receives when a credit derivative is closed to the daily closing price of the market index related to the specific asset class and rating of the deal. This curve indicates expected credit spreads at each indicative level on the related market index. For transactions with unique terms or characteristics where no price quotes are available, management extrapolates credit spreads based on a similar transaction for which the Company has received a spread quote from one of the first three sources within the Company’s spread hierarchy. This alternative transaction will be within the same asset class, have similar underlying assets, similar credit ratings, and similar time to maturity. The Company then calculates the percentage of relative spread change quarter over quarter for the alternative transaction. This percentage change is then applied to the historical credit spread of the transaction for which no price quote was received in order to calculate the transactions’ current spread. Counterparties determine credit spreads by reviewing new issuance pricing for specific asset classes and receiving price quotes from their trading desks for the specific asset in question. These quotes are validated by cross-referencing quotes received from one market source with those quotes received from another market source to ensure reasonableness.
	The premium the Company receives is referred to as the “net spread.” The Company’s pricing model takes into account not only how credit spreads on risks that it assumes affect pricing, but also how the Company’s own credit spread affects the pricing of its deals. The Company’s own credit risk is factored into the determination of net spread based on the impact of changes in the quoted market price for credit protection bought on the Company, as reflected by quoted market prices on CDS referencing AGC or AGM. For credit spreads on the Company’s name the Company obtains the quoted price of CDS contracts traded on AGC and AGM from market data sources published by third parties. The cost to acquire CDS protection referencing AGC or AGM affects the amount of spread on CDS deals that the Company retains and, hence, their fair value. As the cost to acquire CDS protection referencing AGC or AGM increases, the amount of premium the Company retains on a deal generally decreases. As the cost to acquire CDS protection referencing AGC or AGM decreases, the amount of premium the Company retains on a deal generally increases. In the Company’s valuation model, the premium the Company captures is not permitted to go below the minimum rate that the Company would currently charge to assume similar risks. This assumption can have the effect of mitigating the amount of unrealized gains that are recognized on certain CDS contracts. Given the current market conditions and the Company’s own credit spreads, approximately 21% and 61% based on number of deals of the Company's CDS contracts are fair valued using this minimum premium as of December 31, 2014 and December 31, 2013, respectively. The percentage of deals that price using the minimum premiums has fluctuated since December 31, 2013 due to changes in AGM's and AGC's credit spreads. In general when AGM's and AGC's credit spreads narrow, the cost to hedge AGM's and AGC's name declines and more transactions price above previously established floor levels. Meanwhile, when AGM's and AGC's credit spreads widen, the cost to hedge AGM's and AGC's name increases causing more transactions to price at previously established floor levels. The Company corroborates the assumptions in its fair value model, including the portion of exposure to AGC and AGM hedged by its counterparties, with independent third parties each reporting period. The current level of AGC’s and AGM’s own credit spread has resulted in the bank or deal originator hedging a significant portion of its exposure to AGC and AGM. This reduces the amount of contractual cash flows AGC and AGM can capture as premium for selling its protection.
	The amount of premium a financial guaranty insurance market participant can demand is inversely related to the cost of credit protection on the insurance company as measured by market credit spreads assuming all other assumptions remain constant. This is because the buyers of credit protection typically hedge a portion of their risk to the financial guarantor, due to the fact that the contractual terms of the Company's contracts typically do not require the posting of collateral by the guarantor. The extent of the hedge depends on the types of instruments insured and the current market conditions.
	A fair value resulting in a credit derivative asset on protection sold is the result of contractual cash inflows on in-force deals in excess of what a hypothetical financial guarantor could receive if it sold protection on the same risk as of the reporting date. If the Company were able to freely exchange these contracts (i.e., assuming its contracts did not contain proscriptions on transfer and there was a viable exchange market), it would be able to realize a gain representing the difference between the higher contractual premiums to which it is entitled and the current market premiums for a similar contract. The Company determines the fair value of its CDS contracts by applying the difference between the current net spread and the contractual net spread for the remaining duration of each contract to the notional value of its CDS contracts and taking the present value of such amounts discounted at the corresponding LIBOR over the weighted average remaining life of the contract.
	Example
	Following is an example of how changes in gross spreads, the Company’s own credit spread and the cost to buy protection on the Company affect the amount of premium the Company can demand for its credit protection. The assumptions used in these examples are hypothetical amounts. Scenario 1 represents the market conditions in effect on the transaction date and Scenario 2 represents market conditions at a subsequent reporting date.
		Scenario 1						Scenario 2
		bps			% of Total			bps			% of Total
Original gross spread/cash bond price (in bps)	185						500
Bank profit (in bps)	115			62	%		50			10	%
Hedge cost (in bps)	30			16	%		440			88	%
The premium the Company receives per annum (in bps)	40			22	%		10			2	%
In Scenario 1, the gross spread is 185 basis points. The bank or deal originator captures 115 basis points of the original gross spread and hedges 10% of its exposure to AGC, when the CDS spread on AGC was 300 basis points (300 basis points × 10% =/font>30 basis points). Under this scenario the Company receives premium of 40 basis points, or 22% of the gross spread.
In Scenario 2, the gross spread is 500 basis points. The bank or deal originator captures 50 basis points of the original gross spread and hedges 25% of its exposure to AGC, when the CDS spread on AGC was 1,760 basis points (1,760 basis points × 25% =/font>440 basis points). Under this scenario the Company would receive premium of 10 basis points, or 2% of the gross spread. Due to the increased cost to hedge AGC’s name, the amount of profit the bank would expect to receive, and the premium the Company would expect to receive decline significantly.
In this example, the contractual cash flows (the Company premium received per annum above) exceed the amount a market participant would require the Company to pay in today’s market to accept its obligations under the CDS contract, thus resulting in an asset.
Strengths and Weaknesses of Model
The Company’s credit derivative valuation model, like any financial model, has certain strengths and weaknesses.
The primary strengths of the Company’s CDS modeling techniques are:
•	The model takes into account the transaction structure and the key drivers of market value. The transaction structure includes par insured, weighted average life, level of subordination and composition of collateral.
•	The model maximizes the use of market-driven inputs whenever they are available. The key inputs to the model are market-based spreads for the collateral, and the credit rating of referenced entities. These are viewed by the Company to be the key parameters that affect fair value of the transaction.
•	The model is a consistent approach to valuing positions. The Company has developed a hierarchy for market-based spread inputs that helps mitigate the degree of subjectivity during periods of high illiquidity.
The primary weaknesses of the Company’s CDS modeling techniques are:
•	There is no exit market or actual exit transactions. Therefore the Company’s exit market is a hypothetical one based on the Company’s entry market.
•	There is a very limited market in which to validate the reasonableness of the fair values developed by the Company’s model.
•	At December 31, 2014 and 2013, the markets for the inputs to the model were highly illiquid, which impacts their reliability.
•	Due to the non-standard terms under which the Company enters into derivative contracts, the fair value of its credit derivatives may not reflect the same prices observed in an actively traded market of credit derivatives that do not contain terms and conditions similar to those observed in the financial guaranty market.
These contracts were classified as Level 3 in the fair value hierarchy because there is a reliance on at least one unobservable input deemed significant to the valuation model, most significantly the Company's estimate of the value of non-standard terms and conditions of its credit derivative contracts and amount of protection purchased on AGC or AGM's name.
Fair Value Option on FG VIEs’ Assets and Liabilities
The Company elected the fair value option for all the FG VIEs’ assets and liabilities. See Note 10, Consolidated Variable Interest Entities.
The FG VIEs issued securities collateralized by first lien and second lien RMBS as well as loans and receivables. The lowest level input that is significant to the fair value measurement of these assets and liabilities was a Level 3 input (i.e., unobservable), therefore management classified them as Level 3 in the fair value hierarchy. Prices are generally determined with the assistance of an independent third-party. The pricing is based on a discounted cash flow approach and the third-party’s proprietary pricing models. The models to price the FG VIEs’ liabilities used, where appropriate, inputs such as estimated prepayment speeds; market values of the assets that collateralize the securities; estimated default rates (determined on the basis of an analysis of collateral attributes, historical collateral performance, borrower profiles and other features relevant to the evaluation of collateral credit quality); yields implied by market prices for similar securities; house price depreciation/appreciation rates based on macroeconomic forecasts and, for those liabilities insured by the Company, the benefit from the Company’s insurance policy guaranteeing the timely payment of principal and interest, taking into account the timing of the potential default and the Company’s own credit rating. The third-party also utilizes an internal model to determine an appropriate yield at which to discount the cash flows of the security, by factoring in collateral types, weighted-average lives, and other structural attributes specific to the security being priced. The expected yield is further calibrated by utilizing algorithms designed to aggregate market color, received by the third-party, on comparable bonds.
The fair value of the Company’s FG VIE assets is generally sensitive to changes related to estimated prepayment speeds; estimated default rates (determined on the basis of an analysis of collateral attributes such as: historical collateral performance, borrower profiles and other features relevant to the evaluation of collateral credit quality); discount rates implied by market prices for similar securities; and house price depreciation/appreciation rates based on macroeconomic forecasts. Significant changes to some of these inputs could materially change the market value of the FG VIE’s assets and the implied collateral losses within the transaction. In general, the fair value of the FG VIE asset is most sensitive to changes in the projected collateral losses, where an increase in collateral losses typically leads to a decrease in the fair value of FG VIE assets, while a decrease in collateral losses typically leads to an increase in the fair value of FG VIE assets. These factors also directly impact the fair value of the Company’s FG VIE liabilities.
The fair value of the Company’s FG VIE liabilities is also generally sensitive to changes relating to estimated prepayment speeds; market values of the underlying assets; estimated default rates (determined on the basis of an analysis of collateral attributes such as: historical collateral performance, borrower profiles and other features relevant to the evaluation of collateral credit quality); discount rates implied by market prices for similar securities; and house price depreciation/appreciation rates based on macroeconomic forecasts. In addition, the Company’s FG VIE liabilities with recourse are also sensitive to changes in the Company’s implied credit worthiness. Significant changes to any of these inputs could materially change the timing of expected losses within the insured transaction which is a significant factor in determining the implied benefit from the Company’s insurance policy guaranteeing the timely payment of principal and interest for the tranches of debt issued by the FG VIE that is insured by the Company. In general, extending the timing of expected loss payments by the Company into the future typically leads to a decrease in the value of the Company’s insurance and a decrease in the fair value of the Company’s FG VIE liabilities with recourse, while a shortening of the timing of expected loss payments by the Company typically leads to an increase in the value of the Company’s insurance and an increase in the fair value of the Company’s FG VIE liabilities with recourse.
Not Carried at Fair Value
Financial Guaranty Insurance Contracts
The fair value of the Company’s financial guaranty contracts accounted for as insurance was based on management’s estimate of what a similarly rated financial guaranty insurance company would demand to acquire the Company’s in-force book of financial guaranty insurance business. This amount was based on the pricing assumptions management has observed for portfolio transfers that have occurred in the financial guaranty market and included adjustments to the carrying value of unearned premium reserve for stressed losses, ceding commissions and return on capital. The significant inputs were not readily observable. The Company accordingly classified this fair value measurement as Level 3.
Long-Term Debt
The Company’s long-term debt, excluding notes payable, is valued by broker-dealers using third party independent pricing sources and standard market conventions. The market conventions utilize market quotations, market transactions for the Company’s comparable instruments, and to a lesser extent, similar instruments in the broader insurance industry. The fair value measurement was classified as Level 2 in the fair value hierarchy.
The fair value of the notes payable was determined by calculating the present value of the expected cash flows. The Company determines discounted future cash flows using market driven discount rates and a variety of assumptions, including a projection of the LIBOR rate, prepayment and default assumptions, and AGM CDS spreads. The fair value measurement was classified as Level 3 in the fair value hierarchy because there is a reliance on significant unobservable inputs to the valuation model, including the discount rates, prepayment and default assumptions, loss severity and recovery on delinquent loans.
Other Invested Assets
The fair value of the other invested assets was determined by calculating the present value of the expected cash flows. The Company uses a market approach to determine discounted future cash flows using market driven discount rates and a variety of assumptions, including a projection of the LIBOR rate and prepayment and default assumptions. The fair value measurement was classified as Level 3 in the fair value hierarchy because there is a reliance on significant unobservable inputs to the valuation model, including the discount rates, prepayment and default assumptions, loss severity and recovery on delinquent loans.
Other Assets and Other Liabilities
The Company’s other assets and other liabilities consist predominantly of accrued interest, receivables for securities sold and payables for securities purchased, the carrying values of which approximate fair value.
Financial Instruments Carried at Fair Value
Amounts recorded at fair value in the Company’s financial statements are presented in the tables below.
Fair Value Hierarchy of Financial Instruments Carried at Fair Value
As of December 31, 2014
					Fair Value Hierarchy
	Fair Value				Level 1				Level 2				Level 3
	(in millions)
Assets:
Investment portfolio, available-for-sale:
Fixed-maturity securities
Obligations of state and political subdivisions	$	5,795			$	—			$	5,757			$	38
U.S. government and agencies	665				—				665				—
Corporate securities	1,368				—				1,289				79
Mortgage-backed securities:
RMBS	1,285				—				860				425
CMBS	659				—				659				—
Asset-backed securities	417				—				189				228
Foreign government securities	302				—				302				—
Total fixed-maturity securities	10,491				—				9,721				770
Short-term investments	767				359				408				—
Other invested assets (1)	100				—				17				83
Credit derivative assets	68				—				—				68
FG VIEs’ assets, at fair value (2)	1,398				—				—				1,398
Other assets	78				26				17				35
Total assets carried at fair value	$	12,902			$	385			$	10,163			$	2,354
Liabilities:
Credit derivative liabilities	$	963			$	—			$	—			$	963
FG VIEs’ liabilities with recourse, at fair value	1,277				—				—				1,277
FG VIEs’ liabilities without recourse, at fair value	142				—				—				142
Total liabilities carried at fair value	$	2,382			$	—			$	—			$	2,382
Fair Value Hierarchy of Financial Instruments Carried at Fair Value
As of December 31, 2013
					Fair Value Hierarchy
	Fair Value				Level 1				Level 2				Level 3
	(in millions)
Assets:
Investment portfolio, available-for-sale:
Fixed-maturity securities
Obligations of state and political subdivisions	$	5,079			$	—			$	5,043			$	36
U.S. government and agencies	700				—				700				—
Corporate securities	1,340				—				1,204				136
Mortgage-backed securities:
RMBS	1,122				—				832				290
CMBS	549				—				549				—
Asset-backed securities	608				—				340				268
Foreign government securities	313				—				313				—
Total fixed-maturity securities	9,711				—				8,981				730
Short-term investments	904				506				398				—
Other invested assets(1)	127				—				119				8
Credit derivative assets	94				—				—				94
FG VIEs’ assets, at fair value	2,565				—				—				2,565
Other assets	84				27				11				46
Total assets carried at fair value	$	13,485			$	533			$	9,509			$	3,443
Liabilities:
Credit derivative liabilities	$	1,787			$	—			$	—			$	1,787
FG VIEs’ liabilities with recourse, at fair value	1,790				—				—				1,790
FG VIEs’ liabilities without recourse, at fair value	1,081				—				—				1,081
Total liabilities carried at fair value	$	4,658			$	—			$	—			$	4,658
____________________
-1	Includes Level 3 mortgage loans that are recorded at fair value on a non-recurring basis.
-2	Exclude restricted cash.
Changes in Level 3 Fair Value Measurements
The table below presents a roll forward of the Company’s Level 3 financial instruments carried at fair value on a recurring basis during the years ended December 31, 2014 and 2013.
Fair Value Level 3 Rollforward
Recurring Basis
Year Ended December 31, 2014
	Fixed-Maturity Securities
	Obligations					Corporate Securities					RMBS					Asset-					Other				FG VIEs’					Other					Credit					FG VIEs' Liabilities					FG VIEs’ Liabilities
	of State and															Backed					Invested				Assets at					Assets					Derivative					with					without
	Political															Securities					Assets				Fair										Asset					Recourse,					Recourse,
	Subdivisions																								Value										(Liability),					at Fair					at Fair
																																			net(5)					Value					Value
	(in millions)
Fair value as of December 31, 2013	$	36				$	136				$	290				$	268				$	2			$	2,565				$	46				$	(1,693	)			$	(1,790	)			$	(1,081	)
Total pretax realized and unrealized gains/(losses) recorded in:(1)
Net income (loss)	4			(2	)	(46		)	(2	)	21			(2	)	17			(2	)	—				164			(3	)	(11		)	(4	)	823			(6	)	94			(3	)	(43		)	(3	)
Other comprehensive income (loss)	(1		)			(6		)			24					5					6				—					—					—					—					—
Purchases	—					—					263					—					70				—					—					—					—					—
Settlements	(1		)			(5		)			(59		)			(62		)			0				(408		)			—					(25		)			374					22
FG VIE consolidations	—					—					(127		)			—					—				206					—					—					(189		)			(42		)
FG VIE deconsolidations	—					—					13					—					—				(1,129		)			—					—					234					1,002
Fair value as of December 31, 2014	$	38				$	79				$	425				$	228				$	78			$	1,398				$	35				$	(895	)			$	(1,277	)			$	(142	)
Change in unrealized gains/(losses) related to financial instruments held as of December 31, 2014	$	(1	)			$	(6	)			$	21				$	4				$	6			$	141				$	(11	)			$	254				$	(22	)			$	3
Fair Value Level 3 Rollforward
Recurring Basis
Year Ended December 31, 2013
	Fixed-Maturity Securities
	Obligations of state and political subdivisions					Corporate Securities					RMBS					Asset Backed Securities					Other					FG VIEs’					Other					Credit					FG VIEs’ Liabilities					FG VIEs’ Liabilities
																					Invested					Assets at					Assets					Derivative					with					without
																					Assets					Fair										Asset					Recourse,					Recourse,
																										Value										(Liability),					at Fair					at Fair
																																				net(5)					Value					Value
	(in millions)
Fair value as of December 31, 2012	$	35				$	—				$	219				$	306				$	1				$	2,688				$	36				$	(1,793	)			$	(2,090	)			$	(1,051	)
Total pretax realized and unrealized gains/(losses) recorded in:(1)
Net income (loss)	(8		)	(2	)	4			(2	)	13			(2	)	67			(2	)	(1		)	(7	)	686			(3	)	10			(4	)	65			(6	)	(166		)	(3	)	(225		)	(3	)
Other comprehensive income (loss)	13					5					26					(43		)			2					—					—					—					—					—
Purchases	—					130			(8	)	86					80					2			(8	)	—					—					—					—					—
Settlements	(4		)			(3		)			(54		)			(142		)			(2		)			(663		)			—					35					343					168
FG VIE consolidations	—					—					—					—					—					48					—					—					(12		)			(37		)
FG VIE deconsolidations	—					—					—					—					—					(194		)			—					—					135					64
Fair value as of December 31, 2013	$	36				$	136				$	290				$	268				$	2				$	2,565				$	46				$	(1,693	)			$	(1,790	)			$	(1,081	)
Change in unrealized gains/(losses) related to financial instruments held as of December 31, 2013	$	14				$	5				$	27				$	(20	)			$	2				$	623				$	10				$	(139	)			$	(169	)			$	(326	)
___________________
-1	Realized and unrealized gains (losses) from changes in values of Level 3 financial instruments represent gains (losses) from changes in values of those financial instruments only for the periods in which the instruments were classified as Level 3.
-2	Included in net realized investment gains (losses) and net investment income.
-3	Included in fair value gains (losses) on FG VIEs.
-4	Recorded in fair value gains (losses) on CCS.
-5	Represents net position of credit derivatives. The consolidated balance sheet presents gross assets and liabilities based on net counterparty exposure.
-6	Reported in net change in fair value of credit derivatives.
-7	Reported in other income.
-8	Non-cash transaction.
Level 3 Fair Value Disclosures
Quantitative Information About Level 3 Fair Value Inputs
At December 31, 2014
Financial Instrument Description(1)		Fair Value at December 31, 2014(in millions)				Significant Unobservable Inputs		Range						Weighted Average as a Percentage of Current Par Outstanding
Assets:
Fixed-maturity securities:
Obligations of state and political subdivisions		$	38			Rate of inflation		1		%	-	3.00%		2.00%
						Cash flow receipts		0.5		%	-	74.30%		63.00%
						Yield		4.6		%		8.00%		7.30%
						Collateral recovery period		1 month			-	34 years		28 years
Corporate securities		79				Yield		17.80%
RMBS		425				CPR		0.3		%	-	8.10%		3.30%
						CDR		2.7		%	-	10.60%		5.30%
						Loss severity		52.6		%	-	100.00%		75.20%
						Yield		4.7		%	-	11.70%		6.40%
Asset-backed securities:
Investor owned utility		95				Cash flow receipts		100.00%
						Collateral recovery period		4 years
						Discount factor		7.00%
XXX life insurance transactions		133				Yield		7.30%
Other invested assets		83				Discount for lack of liquidity		20.00%
						Recovery on delinquent loans		40.00%
						Default rates		0		%	-	7.00%		5.80%
						Loss severity		40		%	-	75.00%		68.30%
						Prepayment speeds		5		%	-	15.00%		12.30%
						Net asset value (per share)		$	965		-	$1,159		$1,082
FG VIEs’ assets, at fair value		1,398				CPR		0.3		%	-	11.00%		3.30%
						CDR		1.6		%	-	11.80%		5.10%
						Loss severity		40		%	-	100.00%		82.20%
						Yield		2.7		%	-	17.70%		7.90%
Financial Instrument Description(1)		Fair Value at			Significant Unobservable Inputs		Range					Weighted Average as a Percentage of Current Par Outstanding
		December 31, 2014
		(in millions)
Other assets		35			Quotes from third party pricing		$52		-	$61		$57
					Term (years)		5 years
Liabilities:
Credit derivative liabilities, net		(895	)		Year 1 loss estimates		0	%	-	93.00%		2.10%
					Hedge cost (in bps)		20		-	243.8		61.5
					Bank profit (in bps)		1		-	994.4		127
					Internal floor (in bps)		7		-	100		15.9
					Internal credit rating		AAA		-	CCC		AA+
FG VIEs’ liabilities, at fair value		(1,419	)		CPR		0.3	%	-	11.00%		3.30%
					CDR		1.6	%	-	11.80%		5.10%
					Loss severity		40	%	-	100.00%		82.20%
					Yield		2.7	%	-	17.70%		5.80%
____________________
-1	Discounted cash flow is used as valuation technique for all financial instruments.
Quantitative Information About Level 3 Fair Value Inputs
At December 31, 2013
Financial Instrument Description(1)		Fair Value at December 31, 2013(in millions)				Significant Unobservable Inputs		Range						Weighted Average as a Percentage of Current Par Outstanding
Assets:
Fixed-maturity securities:
Obligations of state and political subdivisions		$	36			Rate of inflation		1		%	-	3.00%		2.00%
						Cash flow receipts		0.5		%	-	60.90%		51.10%
						Discount rates		4.6		%	-	9.00%		8.00%
						Collateral recovery period		1 month			-	10 years		3 years
Corporate securities		136				Yield		8.30%
RMBS		290				CPR		1		%	-	15.80%		4.10%
						CDR		5		%	-	25.80%		17.90%
						Loss severity		48.1		%	-	102.50%		87.20%
						Yield		2.5		%	-	9.40%		5.70%
Asset-backed securities:
Investor owned utility		141				Liquidation value (in millions)			$195		-	$245		$228
						Years to liquidation		0 years			-	3 years		2 years
						Collateral recovery period		12 months			-	6 years		3.5 years
						Discount factor		15.30%
XXX life insurance transactions		127				Yield		12.50%
Other invested assets		8				Discount for lack of liquidity		10		%	-	20.00%		20.00%
						Recovery on delinquent loans		20		%	-	60.00%		40.00%
						Default rates		1		%	-	10.00%		3.20%
						Loss severity		40		%	-	90.00%		73.50%
						Prepayment speeds		6		%	-	15.00%		13.10%
FG VIEs’ assets, at fair value		2,565				CPR		0.3		%	-	11.80%		3.60%
						CDR		3		%	-	25.80%		13.60%
						Loss severity		37.5		%	-	102.00%		94.60%
						Yield		3.5		%	-	10.20%		5.40%
Financial Instrument Description(1)		Fair Value at			Significant Unobservable Inputs		Range					Weighted Average as a Percentage of Current Par Outstanding
		December 31, 2013
		(in millions)
Other assets		46			Quotes from third party pricing		$47		-	$53		$50
					Term (years)		5 years
Liabilities:
Credit derivative liabilities, net		(1,693	)		Year 1 loss estimates		0	%	-	48.00%		1.90%
					Hedge cost (in bps)		46.3		-	525		110.1
					Bank profit (in bps)		1		-	1,418.50		250.4
					Internal floor (in bps)		7		-	100		15.6
					Internal credit rating		AAA		-	CCC		AA+
FG VIEs’ liabilities, at fair value		(2,871	)		CPR		0.3	%	-	11.80%		3.60%
					CDR		3	%	-	25.80%		13.60%
					Loss severity		37.5	%	-	102.00%		94.60%
					Yield		3.5	%	-	10.20%		5.40%
____________________
-1	Discounted cash flow is used as valuation technique for all financial instruments.
The carrying amount and estimated fair value of the Company’s financial instruments are presented in the following table.
Fair Value of Financial Instruments
	As of								As of
	31-Dec-14								31-Dec-13
	Carrying				Estimated				Carrying				Estimated
	Amount				Fair Value				Amount				Fair Value
	(in millions)
Assets:
Fixed-maturity securities	$	10,491			$	10,491			$	9,711			$	9,711
Short-term investments	767				767				904				904
Other invested assets	108				110				147				155
Credit derivative assets	68				68				94				94
FG VIEs’ assets, at fair value	1,398				1,398				2,565				2,565
Other assets	184				184				179				179
Liabilities:
Financial guaranty insurance contracts(1)	3,823				6,205				3,783				5,128
Long-term debt	1,303				1,603				816				970
Credit derivative liabilities	963				963				1,787				1,787
FG VIEs’ liabilities with recourse, at fair value	1,277				1,277				1,790				1,790
FG VIEs’ liabilities without recourse, at fair value	142				142				1,081				1,081
Other liabilities	27				27				36				36
____________________
-1	Carrying amount includes the assets and liabilities related to financial guaranty insurance contract premiums, losses, and salvage and subrogation and other recoverables net of reinsurance.

Financial_Guaranty_Contracts_A

Financial Guaranty Contracts Accounted for as Credit Derivatives	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Guaranty Contracts Accounted for as Credit Derivatives	Financial Guaranty Contracts Accounted for as Credit Derivatives
	Accounting Policy
	Credit derivatives are recorded at fair value. Changes in fair value are recorded in “net change in fair value of credit derivatives” on the consolidated statement of operations. Realized gains and other settlements on credit derivatives include credit derivative premiums received and receivable for credit protection the Company has sold under its insured CDS contracts, premiums paid and payable for credit protection the Company has purchased, claims paid and payable and received and receivable related to insured credit events under these contracts, ceding commissions expense or income and realized gains or losses related to their early termination. Fair value of credit derivatives is reflected as either net assets or net liabilities determined on a contract by contract basis in the Company's consolidated balance sheets. See Note 8, Fair Value Measurement, for a discussion on the fair value methodology for credit derivatives.
	Credit Derivatives
	The Company has a portfolio of financial guaranty contracts that meet the definition of a derivative in accordance with GAAP (primarily CDS).
	Credit derivative transactions are governed by ISDA documentation and have different characteristics from financial guaranty insurance contracts. For example, the Company’s control rights with respect to a reference obligation under a credit derivative may be more limited than when the Company issues a financial guaranty insurance contract. In addition, there are more circumstances under which the Company may be obligated to make payments. Similar to a financial guaranty insurance contract, the Company would be obligated to pay if the obligor failed to make a scheduled payment of principal or interest in full. However, the Company may also be required to pay if the obligor becomes bankrupt or if the reference obligation were restructured if, after negotiation, those credit events are specified in the documentation for the credit derivative transactions. Furthermore, the Company may be required to make a payment due to an event that is unrelated to the performance of the obligation referenced in the credit derivative. If events of default or termination events specified in the credit derivative documentation were to occur, the non-defaulting or the non-affected party, which may be either the Company or the counterparty, depending upon the circumstances, may decide to terminate a credit derivative prior to maturity. In that case, the Company may be required to make a termination payment to its swap counterparty upon such termination. The Company may not unilaterally terminate a CDS contract; however, the Company on occasion has mutually agreed with various counterparties to terminate certain CDS transactions.
	Credit Derivative Net Par Outstanding by Sector
	The estimated remaining weighted average life of credit derivatives was 4.7 years at December 31, 2014 and 4.1 years at December 31, 2013. The components of the Company’s credit derivative net par outstanding are presented below.
	Credit Derivatives
	Subordination and Ratings
			As of December 31, 2014												As of December 31, 2013
	Asset Type		Net Par				Original			Current			Weighted		Net Par			Original		Current		Weighted
			Outstanding				Subordination(1)			Subordination(1)			Average		Outstanding			Subordination(1)		Subordination(1)		Average
													Credit									Credit
													Rating									Rating
			(dollars in millions)
	Pooled corporate obligations:
	Collateralized loan obligation/collateral bond obligations		$	11,688			32	%		36.9	%		AAA		$	19,323		32.4	%	34	%	AAA
	Synthetic investment grade pooled corporate		7,640				22.6			20.6			AAA		9,754			21.6		20		AAA
	Synthetic high yield pooled corporate		—				—			—			—		2,690			47.2		41.1		AAA
	TruPS CDOs		3,119				45.3			35.8			BBB-		3,554			45.5		32.9		BB+
	Market value CDOs of corporate obligations		1,174				19.1			20.7			AAA		2,000			24.4		30.5		AAA
	Total pooled corporate obligations		23,621				30.1			30.7			AAA		37,321			31.5		30.6		AAA
	U.S. RMBS:
	Option ARM and Alt-A first lien		1,378				16.3			10.7			BB+		2,609			19.2		8.6		BB-
	Subprime first lien		1,366				31.1			50.5			A		2,930			30.5		51.9		AA-
	Prime first lien		223				10.9			0			B		264			10.9		3.2		CCC
	Closed-end second lien		19				—			—			CCC		23			—		—		B+
	Total U.S. RMBS		2,986				24.8			33.9			BBB		5,826			24.4		30.1		BBB
	CMBS		1,952				35.3			43.6			AAA		3,744			33.5		42.5		AAA
	Other		6,437				—			—			A		7,591			—		—		A-
	Total		$	34,996									AA+		$	54,482						AA+
	____________________
	-1	Represents the sum of subordinate tranches and over-collateralization and does not include any benefit from excess interest collections that may be used to absorb losses.
	Except for TruPS CDOs, the Company’s exposure to pooled corporate obligations is highly diversified in terms of obligors and industries. Most pooled corporate transactions are structured to limit exposure to any given obligor and industry. The majority of the Company’s pooled corporate exposure consists of collateralized loan obligation (“CLO”) or synthetic pooled corporate obligations. Most of these CLOs have an average obligor size of less than 1% of the total transaction and typically restrict the maximum exposure to any one industry to approximately 10%. The Company’s exposure also benefits from embedded credit enhancement in the transactions which allows a transaction to sustain a certain level of losses in the underlying collateral, further insulating the Company from industry specific concentrations of credit risk on these deals.
	The Company’s TruPS CDO asset pools are generally less diversified by obligors and industries than the typical CLO asset pool. Also, the underlying collateral in TruPS CDOs consists primarily of subordinated debt instruments such as TruPS issued by bank holding companies and similar instruments issued by insurance companies, REITs and other real estate related issuers while CLOs typically contain primarily senior secured obligations. However, to mitigate these risks TruPS CDOs were typically structured with higher levels of embedded credit enhancement than typical CLOs.
	The Company’s exposure to “Other” CDS contracts is also highly diversified. It includes $2.0 billion of exposure to one pooled infrastructure transaction comprising diversified pools of international infrastructure project transactions and loans to regulated utilities. These pools were all structured with underlying credit enhancement sufficient for the Company to attach at AAA levels at origination. The remaining $4.4 billion of exposure in “Other” CDS contracts comprises numerous deals across various asset classes, such as commercial receivables, international RMBS, infrastructure, regulated utilities and consumer receivables.
	Distribution of Credit Derivative Net Par Outstanding by Internal Rating
			As of December 31, 2014							As of December 31, 2013
	Ratings		Net Par				% of Total			Net Par				% of Total
			Outstanding							Outstanding
			(dollars in millions)
	AAA		$	21,817			62.3	%		$	38,244			70.2	%
	AA		5,398				15.4			3,648				6.7
	A		1,982				5.7			3,636				6.7
	BBB		2,774				8			4,161				7.6
	BIG		3,025				8.6			4,793				8.8
	Credit derivative net par outstanding		$	34,996			100	%		$	54,482			100	%
	Fair Value of Credit Derivatives
	Net Change in Fair Value of Credit Derivatives Gain (Loss)
		Year Ended December 31,
		2014				2013				2012
		(in millions)
	Realized gains on credit derivatives	$	73			$	121			$	128
	Net credit derivative losses (paid and payable) recovered and recoverable and other settlements	(50		)		(163		)		(236		)
	Realized gains (losses) and other settlements on credit derivatives	23				(42		)		(108		)
	Net change in unrealized gains (losses) on credit derivatives:
	Pooled corporate obligations	(18		)		(32		)		59
	U.S. RMBS	814				(69		)		(551		)
	CMBS	2				—				2
	Other(1)	2				208				13
	Net change in unrealized gains (losses) on credit derivatives(2)	800				107				(477		)
	Net change in fair value of credit derivatives	$	823			$	65			$	(585	)
	____________________
-1	“Other” includes all other U.S. and international asset classes, such as commercial receivables, international infrastructure, international RMBS securities, and pooled infrastructure securities.
-2	Except for net estimated credit impairments (i.e., net expected loss to be paid as discussed in Note 6), the unrealized gains and losses on credit derivatives are expected to reduce to zero as the exposure approaches its maturity date. With considerable volatility continuing in the market, unrealized gains (losses) on credit derivatives may fluctuate significantly in future periods.
The table below sets out the net par amount of credit derivative contracts that the Company and its counterparties agreed to terminate on a consensual basis.
Net Par and Realized Gains (Losses) on Credit Derivatives
from Terminations of CDS Contracts
	Year Ended December 31,
	2014				2013				2012
	(in millions)
Net par of terminated CDS contracts	$	3,591			$	4,054			$	2,264
Realized gains (losses) and other settlements	1				21				3
During 2014, unrealized fair value gains were generated primarily in the U.S. RMBS prime first lien, Option ARM and subprime sectors. This is primarily due to a significant unrealized fair value gain in the Option ARM and Alt-A first lien sector of approximately $543 million, as a result of the terminations of three large Alt-A first lien resecuritization transactions and one Option ARM first lien transaction during the period. In addition, there was an unrealized gain of approximately $346 million related to the change in index used to determine fair value during the fourth quarter of 2014. In the fourth quarter of 2014, new market indices were published on Option ARM and Alt-A first lien securitizations. As part of the Company’s normal review process the Company reviewed these indices and based upon the collateral make-up, collateral vintage, and collateral loss experience, determined it to be a better market indication for the Company’s Option ARM and Alt-A first lien securitizations. The unrealized fair value gains were partially offset by unrealized fair value losses generated by wider implied net spreads. The wider implied net spreads were primarily a result of the decreased cost to buy protection in AGC’s and AGM’s name, as the market cost of AGC's and AGM’s credit protection decreased during the period. These transactions were pricing at or above their floor levels (or the minimum rate at which the Company would consider assuming these risks based on historical experience); therefore when the cost of purchasing CDS protection on AGC and AGM, which management refers to as the CDS spread on AGC and AGM, decreased the implied spreads that the Company would expect to receive on these transactions increased.
During 2013, unrealized fair value gains were generated in the “other” sector primarily as a result of the termination of a film securitization transaction and a U.K. infrastructure transaction, as well as price improvement on a XXX life securitization transaction. These unrealized gains were partially offset by unrealized fair value losses in the prime first lien, Alt-A, Option ARM and subprime RMBS sectors due to wider implied net spreads. The wider implied net spreads were primarily a result of the decreased cost to buy protection in AGC’s name as the market cost of AGC’s credit protection decreased. These transactions were pricing above their floor levels; therefore when the cost of purchasing CDS protection on AGC, decreased the implied spreads that the Company would expect to receive on these transactions increased. The cost of AGM’s credit protection also decreased slightly during 2013, but did not lead to significant fair value losses, as the majority of AGM policies continue to price at floor levels. The company terminated a film securitization CDS for a payment of $120 million which was recorded in realized gains (losses) and other settlements on credit derivatives, with a corresponding release of the unrealized loss recorded in unrealized gains (losses) on credit derivatives of $127 million for a net change in fair value of credit derivatives of $7 million.
During 2012, U.S. RMBS unrealized fair value losses were generated primarily in the prime first lien, Alt-A, Option ARM and subprime RMBS sectors primarily as a result of the decreased cost to buy protection in AGC's name as the market cost of AGC's credit protection decreased. These transactions were pricing above their floor levels therefore when the cost of purchasing CDS protection on AGC decreased, the implied spreads that the Company would expect to receive on these transactions increased. The cost of AGM's credit protection also decreased during 2012, but did not lead to significant fair value losses, as the majority of AGM policies continue to price at floor levels. In addition, 2012 included an $85 million unrealized gain relating to R&W benefits from the agreement with Deutsche Bank.
The impact of changes in credit spreads will vary based upon the volume, tenor, interest rates, and other market conditions at the time these fair values are determined. In addition, since each transaction has unique collateral and structural terms, the underlying change in fair value of each transaction may vary considerably. The fair value of credit derivative contracts also reflects the change in the Company’s own credit cost based on the price to purchase credit protection on AGC and AGM. The Company determines its own credit risk based on quoted CDS prices traded on the Company at each balance sheet date.
Five-Year CDS Spread
on AGC and AGM
Quoted price of CDS contract (in basis points)
	As of			As of			As of
	31-Dec-14			31-Dec-13			31-Dec-12
AGC	323			460			678
AGM	325			525			536
One-Year CDS Spread
on AGC and AGM
Quoted price of CDS contract (in basis points)
	As of			As of			As of
	31-Dec-14			31-Dec-13			31-Dec-12
AGC	80			185			270
AGM	85			220			257
Fair Value of Credit Derivatives Assets (Liabilities)
and Effect of AGC and AGM
Credit Spreads
	As of				As of
	31-Dec-14				31-Dec-13
	(in millions)
Fair value of credit derivatives before effect of AGC and AGM credit spreads	$	(2,029	)		$	(3,442	)
Plus: Effect of AGC and AGM credit spreads	1,134				1,749
Net fair value of credit derivatives	$	(895	)		$	(1,693	)
The fair value of CDS contracts at December 31, 2014, before considering the implications of AGC’s and AGM’s credit spreads, is a direct result of continued wide credit spreads in the fixed income security markets and ratings downgrades. The asset classes that remain most affected are 2005-2007 vintages of prime first lien, Alt-A, Option ARM, subprime RMBS deals as well as trust-preferred and pooled corporate securities. Comparing December 31, 2014 with December 31, 2013,there was a narrowing of spreads primarily related to Alt-A first lien, Option ARM, and subprime RMBS transactions, as well as the Company's pooled corporate obligations. This narrowing of spreads combined with the runoff of par outstanding and termination of CDS contracts, resulted in a gain of approximately $1,413 million, before taking into account AGC’s or AGM’s credit spreads.
Management believes that the trading level of AGC’s and AGM’s credit spreads over the past several years has been due to the correlation between AGC’s and AGM’s risk profile and the current risk profile of the broader financial markets and to increased demand for credit protection against AGC and AGM as the result of its financial guaranty volume, as well as the overall lack of liquidity in the CDS market. Offsetting the benefit attributable to AGC’s and AGM’s credit spread were higher credit spreads in the fixed income security markets. The higher credit spreads in the fixed income security market are due to the lack of liquidity in the high yield CDO, TruPS CDO, and CLO markets as well as continuing market concerns over the 2005-2007 vintages of RMBS.
The following table presents the fair value and the present value of expected claim payments or recoveries (i.e., net expected loss to be paid as described in Note 6) for contracts accounted for as derivatives.
Net Fair Value and Expected Losses
Credit Derivatives by Sector
		Fair Value of Credit Derivative								Expected Loss to be (Paid) Recovered (1)
		Asset (Liability), net
Asset Type		As of				As of				As of				As of
		31-Dec-14				31-Dec-13				31-Dec-14				31-Dec-13
		(in millions)
Pooled corporate obligations		$	(49	)		$	(30	)		$	(23	)		$	(48	)
U.S. RMBS		(494		)		(1,308		)		(73		)		(175		)
CMBS		0				(2		)		—				—
Other		(352		)		(353		)		38				39
Total		$	(895	)		$	(1,693	)		$	(58	)		$	(184	)
____________________
(1)	Includes R&W benefit of $86 million as of December 31, 2014 and $180 million as of December 31, 2013.
Ratings Sensitivities of Credit Derivative Contracts
Within the Company’s insured CDS portfolio, the transaction documentation for approximately $6.1 billion in CDS gross par insured as of December 31, 2014 requires AGC and Assured Guaranty Re Overseas Ltd. ("AGRO") to post eligible collateral to secure its obligations to make payments under such contracts. Eligible collateral is generally cash or U.S. government or agency securities; eligible collateral other than cash is valued at a discount to the face amount.
•	For approximately $5.9 billion of such contracts, AGC has negotiated caps such that the posting requirement cannot exceed a certain fixed amount, regardless of the mark-to-market valuation of the exposure or the financial strength ratings of AGC. For such contracts, AGC need not post on a cash basis more than $665 million, although the value of the collateral posted may exceed such fixed amount depending on the advance rate agreed with the counterparty for the particular type of collateral posted.
•	For the remaining approximately $242 million of such contracts, AGC or AGRO could be required from time to time to post additional collateral without such cap based on movements in the mark-to-market valuation of the underlying exposure.
As of December 31, 2014, the Company posted approximately $376 million to secure obligations under its CDS exposure, of which approximately $25 million related to such $242 million of notional. As of December 31, 2013, the Company posted approximately $677 million, of which approximately $62 million related to $347 million of notional where AGC or AGRO could be required to post additional collateral based on movements in the mark-to-market valuation of the underlying exposure.
On May 6, 2014, AGC’s affiliate AG Financial Products Inc. and one of its CDS counterparties amended the ISDA master agreement between them, at no cost, to remove a termination trigger based on a rating downgrade of the other party. With this termination, none of the Company's insured CDS portfolio is subject to a rating-based termination trigger that could result in the Company being obligated to make a termination payment to a CDS counterparty.
Sensitivity to Changes in Credit Spread
The following table summarizes the estimated change in fair values on the net balance of the Company’s credit derivative positions assuming immediate parallel shifts in credit spreads on AGC and AGM and on the risks that they both assume.
Effect of Changes in Credit Spread
As of December 31, 2014
Credit Spreads(1)		Estimated Net				Estimated Change
		Fair Value				in Gain/(Loss)
		(Pre-Tax)				(Pre-Tax)
		(in millions)
100% widening in spreads		$	(1,821	)		$	(926	)
50% widening in spreads		(1,358		)		(463		)
25% widening in spreads		(1,128		)		(233		)
10% widening in spreads		(989		)		(94		)
Base Scenario		(895		)		—
10% narrowing in spreads		(809		)		86
25% narrowing in spreads		(679		)		216
50% narrowing in spreads		(466		)		429
____________________
-1	Includes the effects of spreads on both the underlying asset classes and the Company’s own credit spread.

Consolidated_Variable_Interest

Consolidated Variable Interest Entities	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Consolidated Variable Interest Entities	Consolidated Variable Interest Entities
	The Company provides financial guaranties with respect to debt obligations of special purpose entities, including VIEs. AGC and AGM do not sponsor any VIEs when underwriting third party financial guaranty insurance or credit derivative transactions, nor has either of them acted as the servicer or collateral manager for any VIE obligations that it insures. The transaction structure generally provides certain financial protections to the Company. This financial protection can take several forms, the most common of which are overcollateralization, first loss protection (or subordination) and excess spread. In the case of overcollateralization (i.e., the principal amount of the securitized assets exceeds the principal amount of the structured finance obligations guaranteed by the Company), the structure allows defaults of the securitized assets before a default is experienced on the structured finance obligation guaranteed by the Company. In the case of first loss, the financial guaranty insurance policy only covers a senior layer of losses experienced by multiple obligations issued by special purpose entities, including VIEs. The first loss exposure with respect to the assets is either retained by the seller or sold off in the form of equity or mezzanine debt to other investors. In the case of excess spread, the financial assets contributed to special purpose entities, including VIEs, generate cash flows that are in excess of the interest payments on the debt issued by the special purpose entity. Such excess spread is typically distributed through the transaction’s cash flow waterfall and may be used to create additional credit enhancement, applied to redeem debt issued by the special purpose entities, including VIEs (thereby, creating additional overcollateralization), or distributed to equity or other investors in the transaction.
	AGC and AGM are not primarily liable for the debt obligations issued by the VIEs they insure and would only be required to make payments on those insured debt obligations in the event that the issuer of such debt obligations defaults on any principal or interest due and only for the amount of the shortfall. AGL’s and its Subsidiaries’ creditors do not have any rights with regard to the collateral supporting the debt issued by the FG VIEs. Proceeds from sales, maturities, prepayments and interest from such underlying collateral may only be used to pay Debt Service on VIE liabilities. Net fair value gains and losses on FG VIEs are expected to reverse to zero at maturity of the VIE debt, except for net premiums received and net claims paid by AGC or AGM under the financial guaranty insurance contract. The Company’s estimate of expected loss to be paid for FG VIEs is included in Note 6, Expected Loss to be Paid.
	Accounting Policy
	The Company evaluates whether it is the primary beneficiary of its VIEs. If the Company concludes that it is the primary beneficiary, it is required to consolidate the entire VIE in the Company's financial statements and eliminate the effects of the financial guaranty insurance contracts issued by AGM and AGC on the consolidated FG VIEs debt obligations.
	The primary beneficiary of a VIE is the enterprise that has both 1) the power to direct the activities of a VIE that most significantly impact the entity's economic performance; and 2) the obligation to absorb losses of the entity that could potentially be significant to the VIE or the right to receive benefits from the entity that could potentially be significant to the VIE.
	As part of the terms of its financial guaranty contracts, the Company obtains certain protective rights with respect to the VIE that are triggered by the occurrence of certain events, such as failure to be in compliance with a covenant due to poor deal performance or a deterioration in a servicer or collateral manager's financial condition. At deal inception, the Company typically is not deemed to control a VIE; however, once a trigger event occurs, the Company's control of the VIE typically increases. The Company continuously evaluates its power to direct the activities that most significantly impact the economic performance of VIEs that have debt obligations insured by the Company and, accordingly, where the Company is obligated to absorb VIE losses or receive benefits that could potentially be significant to the VIE. The Company obtains protective rights under its insurance contracts that give the Company additional controls over a VIE if there is either deterioration of deal performance or in the financial health of the deal servicer. The Company is deemed to be the control party for certain VIEs under GAAP, typically when its protective rights give it the power to both terminate and replace the deal servicer, which are characteristics specific to the Company's financial guaranty contracts. If the protective rights that could make the Company the control party have not been triggered, then the VIE is not consolidated. If the Company is deemed no longer to have those protective rights, the transaction is deconsolidated.
	The FG VIEs' liabilities that are insured by the Company are considered to be with recourse, because the Company guarantees the payment of principal and interest regardless of the performance of the related FG VIEs' assets. FG VIEs' liabilities that are not insured by the Company are considered to be without recourse, because the payment of principal and interest of these liabilities is wholly dependent on the performance of the FG VIEs' assets.
	The Company has limited contractual rights to obtain the financial records of its consolidated FG VIEs. The FG VIEs do not prepare separate GAAP financial statements; therefore, the Company compiles GAAP financial information for them based on trustee reports prepared by and received from third parties. Such trustee reports are not available to the Company until approximately 30 days after the end of any given period. The time required to perform adequate reconciliations and analyses of the information in these trustee reports results in a one quarter lag in reporting the FG VIEs' activities. The Company records the fair value of FG VIE assets and liabilities based on modeled prices. The Company updates the model assumptions each reporting period for the most recent available information, which incorporates the impact of material events that may have occurred since the quarter lag date. Interest income and interest expense are derived from the trustee reports and included in “fair value gains (losses) on FG VIEs” in the consolidated statement of operations. The Company has elected the fair value option for assets and liabilities classified as FG VIEs' assets and liabilities because the carrying amount transition method was not practical.
	The cash flows generated by the FG VIE assets, including R&W recoveries, are classified as cash flows from investing activities. Paydowns of FG liabilities are supported by the cash flows generated by FG VIE assets, and for liabilities with recourse, possibly claim payments made by AGM or AGC under its financial guaranty insurance contracts. Paydowns of FG liabilities both with and without recourse are classified as cash flows used in financing activities by the Company. Interest income, interest expense and other expenses of the FG VIE assets and liabilities are classified as operating cash flows. Claim payments made by AGC and AGM under the financial guaranty contracts issued to the FG VIEs are eliminated upon consolidation and therefore such claim payments are treated as paydowns of FG VIE liabilities as a financing activity as opposed to an operating activity of AGM and AGC.
	Consolidated FG VIEs
	Number of FG VIEs Consolidated
		Year Ended December 31,
		2014			2013			2012
	Beginning of the period, December 31	40			33			33
	Consolidated(1)	2			11			2
	Deconsolidated(1)	(8	)		(3	)		—
	Matured	(2	)		(1	)		(2	)
	End of the period, December 31	32			40			33
	____________________
	-1	Net gain on deconsolidation was $120 million and net loss on consolidation was $26 million in 2014. Net loss on consolidation and deconsolidation was $7 million in 2013 and $6 million in 2012, respectively, and recorded in “fair value gains (losses) on FG VIEs” in the consolidated statement of operations.
	The total unpaid principal balance for the FG VIEs’ assets that were over 90 days or more past due was approximately $183 million at December 31, 2014 and $750 million at December 31, 2013. The aggregate unpaid principal of the FG VIEs’ assets was approximately $941 million greater than the aggregate fair value at December 31, 2014, excluding the effect of R&W settlements. The aggregate unpaid principal of the FG VIEs’ assets was approximately $1,940 million greater than the aggregate fair value at December 31, 2013, excluding the effect of R&W settlements. The change in the instrument-specific credit risk of the FG VIEs’ assets held as of December 31, 2014 that was recorded in the consolidated statements of operations for 2014 were gains of $116 million. The change in the instrument-specific credit risk of the FG VIEs’ assets held as of December 31, 2013 that was recorded in the consolidated statements of operations for 2013 were gains of $340 million. The change in the instrument-specific credit risk of the FG VIEs’ assets for 2012 were gains of $413 million. To calculate the instrument specific credit risk, the changes in the fair value of the FG VIE assets are allocated between those changes that are due to the instrument specific credit risk and those are due to other factors, including interest rates. The instrument specific credit risk amount is determined by using expected contractual cash flows vs. current expected cash flows discounted at original contractual rate. The net present value is calculated by discounting the expected cash flows of the underlying security, excluding the Company’s financial guaranty insurance, at the relevant effective interest rate.
	The unpaid principal for FG VIE liabilities with recourse was $1,912 million and $2,316 million as of December 31, 2014 and December 31, 2013, respectively. FG VIE liabilities with recourse will mature at various dates ranging from 2025 to 2046. The aggregate unpaid principal balance of the FG VIE liabilities with and without recourse was approximately $916 million greater than the aggregate fair value of the FG VIEs’ liabilities as of December 31, 2014. The aggregate unpaid principal balance was approximately $1,611 million greater than the aggregate fair value of the FG VIEs’ liabilities as of December 31, 2013.
	The table below shows the carrying value of the consolidated FG VIEs’ assets and liabilities in the consolidated financial statements, segregated by the types of assets that collateralize their respective debt obligations.
	Consolidated FG VIEs
	By Type of Collateral
		As of December 31, 2014								As of December 31, 2013
		Assets				Liabilities				Assets			Liabilities
		(in millions)
	With recourse:
	U.S. RMBS first lien	$	632			$	581			$	630		$	791
	U.S. RMBS second lien	238				327				460			640
	Other	369				369				359			359
	Total with recourse	1,239				1,277				1,449			1,790
	Without recourse	163				142				1,116			1,081
	Total	$	1,402			$	1,419			$	2,565		$	2,871
	The consolidation of FG VIEs has a significant effect on net income and shareholder’s equity due to (1) changes in fair value gains (losses) on FG VIE assets and liabilities, (2) the elimination of premiums and losses related to the AGC and AGM FG VIE liabilities with recourse and (3) the elimination of investment balances related to the Company’s purchase of AGC and AGM insured FG VIE debt. Upon consolidation of a FG VIE, the related insurance and, if applicable, the related investment balances, are considered intercompany transactions and therefore eliminated. Such eliminations are included in the table below to present the full effect of consolidating FG VIEs.
	Effect of Consolidating FG VIEs on Net Income,
	Cash Flows From Operating Activities and Shareholders’ Equity
		Year Ended December 31,
		2014				2013				2012
		(in millions)
	Net earned premiums	$	(32	)		$	(60	)		$	(153	)
	Net investment income	(11		)		(13		)		(13		)
	Net realized investment gains (losses)	(5		)		2				4
	Fair value gains (losses) on FG VIEs	255				346				191
	Other income (loss)	(2		)		—				—
	Loss and LAE	30				21				65
	Effect on net income before tax	235				296				94
	Less: tax provision (benefit)	82				103				32
	Effect on net income (loss)	$	153			$	193			$	62
	Effect on cash flows from operating activities	$	68			$	(136	)		$	166
		As of				As of
		31-Dec-14				31-Dec-13
		(in millions)
	Effect on shareholders’ equity (decrease) increase	$	(44	)		$	(172	)
	Fair value gains (losses) on FG VIEs represent the net change in fair value on the consolidated FG VIEs’ assets and liabilities. In 2014, the Company recorded a pre-tax net fair value gain on consolidated FG VIEs of $255 million. The primary driver of this gain, $120 million, was a result of the deconsolidation of seven VIEs. In addition, there was gain of $37 million resulting from the Company exercising its option to accelerate two second lien RMBS bonds. The remainder of the gain for the period was driven by the price appreciation on the Company's FG VIE assets during the year resulting from improvements in the underlying collateral, as well as large principal paydowns made on the Company's FG VIEs.
	In 2013, the Company recorded a pre-tax net fair value gain of consolidated FG VIEs of $346 million. The gain was primarily driven by R&W benefits received on several VIE assets as a result of settlements with various counterparties throughout the year. These R&W settlements resulted in a gain of approximately $265 million. The remainder of the gain was driven by price appreciation on the Company's FG VIE assets during the year resulting from improvements in the underlying collateral, as well as large principal paydowns made on the Company's FG VIEs.
	In 2012, the Company recorded a pre-tax fair value gain on FG VIEs of $191 million. The majority of this gain, approximately $166 million, is a result of a R&W benefit received on several VIE assets as a result of a settlement with Deutsche Bank that closed in 2012. While prices continued to appreciate during the period on the Company's FG VIE assets and liabilities, gains in the year were primarily driven by large principal paydowns made on the Company's FG VIEs.
	Non-Consolidated VIEs
	As of December 31, 2014 and December 31, 2013, the Company had issued financial guaranty contracts for approximately 930 and 1,000 VIEs, respectively, that it did not consolidate. To date, the Company’s analyses have indicated that it does not have a controlling financial interest in any other VIEs and, as a result, they are not consolidated in the consolidated financial statements. The Company’s exposure provided through its financial guaranties with respect to debt obligations of special purpose entities is included within net par outstanding in Note 3, Outstanding Exposure.

Investments_and_Cash

Investments and Cash	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Investments and Cash	Investments and Cash
	Accounting Policy
	The vast majority of the Company's investment portfolio is composed of fixed-maturity and short-term investments, classified as available-for-sale at the time of purchase (approximately 99% based on fair value at December 31, 2014), and therefore carried at fair value. Changes in fair value for other-than-temporarily-impaired ("OTTI") securities are bifurcated between credit losses and non-credit changes in fair value. The credit loss on OTTI securities is recorded in the statement of operations and the non-credit component of the change in fair value of securities, whether OTTI or not, is recorded in OCI. For securities where the Company has the intent to sell or it is more-likely-than-not that it will be required to sell the security before recovery, declines in fair value are recorded in the consolidated statements of operations.
	Credit losses reduce the amortized cost of impaired securities. The amortized cost basis is adjusted for accretion and amortization (using the effective interest method) with a corresponding entry recorded in net investment income.
	Realized gains and losses on sales of investments are determined using the specific identification method. Realized loss includes amounts recorded for other-than-temporary impairments on debt securities and the declines in fair value of securities for which the Company has the intent to sell the security or inability to hold until recovery of amortized cost.
	For mortgage‑backed securities, and any other holdings for which there is prepayment risk, prepayment assumptions are evaluated and revised as necessary. Any necessary adjustments due to changes in effective yields and maturities are recognized in net investment income.
	The Company purchases securities that it has insured, and for which it has expected losses to be paid, in order to mitigate the economic effect of insured losses ("loss mitigation securities"). These securities were purchased at a discount and are accounted for excluding the effects of the Company’s insurance.
	Short-term investments, which are those investments with a maturity of less than one year at time of purchase, are carried at fair value and include amounts deposited in money market funds.
	Other invested assets primarily include:
	•	preferred stocks, which are carried at fair value with changes in unrealized gains and losses recorded in OCI,
	•	trading securities, which are carried at fair value with unrealized gains and losses recorded in net income,
	•	a 50% equity investment acquired in a restructuring of an insured CDS carried at its proportionate share of the underlying entity's U.S. GAAP equity value.
	Cash consists of cash on hand and demand deposits. As a result of the lag in reporting FG VIEs, cash and short-term investments do not reflect cash outflow to the holders of the debt issued by the FG VIEs for claim payments made by the Company's insurance subsidiaries to the consolidated FG VIEs until the subsequent reporting period.
	Assessment for Other-Than Temporary Impairments
	The amount of other-than-temporary-impairment recognized in earnings depends on whether (1) an entity intends to sell the security or (2) it is more-likely-than-not that the entity will be required to sell the security before recovery of its amortized cost basis.
	If an entity does not intend to sell the security and it is not more-likely-than-not that the Company will be required to sell the security before recovery of its amortized cost basis, the other-than-temporary-impairment is separated into (1) the amount representing the credit loss and (2) the amount related to all other factors.
	The Company has a formal review process to determine other-than-temporary-impairment for securities in its investment portfolio where there is no intent to sell and it is not more-likely-than-not that it will be required to sell the security before recovery. Factors considered when assessing impairment include:
	•	a decline in the market value of a security by 20% or more below amortized cost for a continuous period of at least six months;
	•	a decline in the market value of a security for a continuous period of 12 months;
	•	recent credit downgrades of the applicable security or the issuer by rating agencies;
	•	the financial condition of the applicable issuer;
	•	whether loss of investment principal is anticipated;
	•	the impact of foreign exchange rates; and
	•	whether scheduled interest payments are past due.
	The Company assesses the ability to recover the amortized cost by comparing the net present value of projected future cash flows with the amortized cost of the security. If the security is impaired and the net present value is less than the amortized cost of the investment, an other-than-temporary impairment is recorded. The net present value is calculated by discounting the Company's estimate of projected future cash flows at the effective interest rate implicit in the debt security at the time of purchase. The Company's estimates of projected future cash flows are driven by assumptions regarding probability of default and estimates regarding timing and amount of recoveries associated with a default. The Company develops these estimates using information based on historical experience, credit analysis and market observable data, such as industry analyst reports and forecasts, sector credit ratings and other relevant data. For mortgage‑backed and asset backed securities, cash flow estimates also include prepayment and other assumptions regarding the underlying collateral including default rates, recoveries and changes in value. The assumptions used in these projections requires the use of significant management judgment.
	The Company's assessment of a decline in value included management's current assessment of the factors noted above. The Company also seeks advice from its outside investment managers. If that assessment changes in the future, the Company may ultimately record a loss after having originally concluded that the decline in value was temporary.
	Net Investment Income and Realized Gains (Losses)
	Net investment income is a function of the yield that the Company earns on invested assets and the size of the portfolio. The investment yield is a function of market interest rates at the time of investment as well as the type, credit quality and maturity of the invested assets. Accrued investment income was $98 million and $93 million as of December 31, 2014 and December 31, 2013, respectively.
	Net Investment Income
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Income from fixed-maturity securities managed by third parties	$	324		$	322		$	346
	Income from internally managed securities:
	Fixed maturities	74			74			60
	Other invested assets	13			5			6
	Other	1			0			1
	Gross investment income	412			401			413
	Investment expenses	(9		)	(8		)	(9		)
	Net investment income	$	403		$	393		$	404
	Net Realized Investment Gains (Losses)
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Gross realized gains on available-for-sale securities	$	14		$	73		$	29
	Gross realized gains on other assets in investment portfolio	8			40			14
	Gross realized losses on available-for-sale securities	(5		)	(12		)	(23		)
	Gross realized losses on other assets in investment portfolio	(2		)	(7		)	(2		)
	Other-than-temporary impairment	(75		)	(42		)	(17		)
	Net realized investment gains (losses)	$	(60	)	$	52		$	1
	The following table presents the roll-forward of the credit losses of fixed-maturity securities for which the Company has recognized an other-than-temporary-impairment and where the portion of the fair value adjustment related to other factors was recognized in OCI.
	Roll Forward of Credit Losses
	in the Investment Portfolio
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Balance, beginning of period	$	80		$	64		$	47
	Additions for credit losses on securities for which an other-than-temporary-impairment was not previously recognized	64			18			14
	Eliminations of securities issued by FG VIEs	(15		)	—			—
	Reductions for securities sold during the period	(12		)	(21		)	—
	Additions for credit losses on securities for which an other-than-temporary-impairment was previously recognized	7			19			3
	Balance, end of period	$	124		$	80		$	64
	Investment Portfolio
	Fixed-Maturity Securities and Short-Term Investments
by Security Type
As of December 31, 2014
Investment Category		Percent		Amortized			Gross			Gross			Estimated			AOCI(2)			Weighted
		of		Cost			Unrealized			Unrealized			Fair			Gain			Average
		Total(1)					Gains			Losses			Value			(Loss) on			Credit
																Securities			Quality
																with			(3)
																Other-Than-Temporary Impairment
		(dollars in millions)
Fixed-maturity securities:
Obligations of state and political subdivisions		50	%	$	5,416		$	380		$	(1	)	$	5,795		$	7		AA
U.S. government and agencies		6		635			31			(1		)	665			—			AA+
Corporate securities		12		1,320			53			(5		)	1,368			(2		)	A
Mortgage-backed securities(4):		—
RMBS		12		1,255			51			(21		)	1,285			0			A-
CMBS		6		639			20			0			659			—			AAA
Asset-backed securities		4		411			9			(3		)	417			3			BBB-
Foreign government securities		3		296			8			(2		)	302			—			AA+
Total fixed-maturity securities		93		9,972			552			(33		)	10,491			8			AA-
Short-term investments		7		767			0			0			767			0			AA+
Total investment portfolio		100	%	$	10,739		$	552		$	(33	)	$	11,258		$	8		AA-
Fixed-Maturity Securities and Short-Term Investments
by Security Type
As of December 31, 2013
Investment Category		Percent		Amortized			Gross			Gross			Estimated			AOCI			Weighted
		of		Cost			Unrealized			Unrealized			Fair			Gain			Average
		Total(1)					Gains			Losses			Value			(Loss) on			Credit
																Securities			Quality
																with			(3)
																Other-Than-Temporary Impairment
		(dollars in millions)
Fixed-maturity securities:
Obligations of state and political subdivisions		47	%	$	4,899		$	219		$	(39	)	$	5,079		$	4		AA
U.S. government and agencies		6		674			32			(6		)	700			—			AA+
Corporate securities		13		1,314			44			(18		)	1,340			0			A
Mortgage-backed securities(4):
RMBS		11		1,160			34			(72		)	1,122			(43		)	A
CMBS		5		536			17			(4		)	549			—			AAA
Asset-backed securities		6		605			10			(7		)	608			2			BBB+
Foreign government securities		3		300			14			(1		)	313			—			AA+
Total fixed-maturity securities		91		9,488			370			(147		)	9,711			(37		)	AA-
Short-term investments		9		904			0			0			904			—			AAA
Total investment portfolio		100	%	$	10,392		$	370		$	(147	)	$	10,615		$	(37	)	AA-
____________________
-1	Based on amortized cost.
-2	Accumulated OCI. See also Note 21, Other Comprehensive Income.
-3	Ratings in the tables above represent the lower of the Moody’s and S&P classifications except for bonds purchased for loss mitigation or risk management strategies, which use internal ratings classifications. The Company’s portfolio consists primarily of high-quality, liquid instruments.
-4	Government-agency obligations were approximately 44% of mortgage backed securities as of December 31, 2014 and 50% as of December 31, 2013 based on fair value.
The Company’s investment portfolio in tax-exempt and taxable municipal securities includes issuances by a wide number of municipal authorities across the U.S. and its territories. Securities rated lower than A-/A3 by S&P or Moody’s are not eligible to be purchased for the Company’s portfolio unless acquired for loss mitigation or risk management strategies.
The following tables present the fair value of the Company’s available-for-sale portfolio of obligations of state and political subdivisions as of December 31, 2014 and December 31, 2013 by state.
Fair Value of Available-for-Sale Portfolio of
Obligations of State and Political Subdivisions
As of December 31, 2014 (1)
State		State			Local			Revenue Bonds			Fair			Amortized			Average
		General			General						Value			Cost			Credit
		Obligation			Obligation												Rating
		(in millions)
Texas		$	60		$	293		$	305		$	658		$	613		AA
New York		13			41			551			605			571			AA
California		45			70			377			492			449			A+
Florida		47			34			256			337			311			AA-
Illinois		20			99			177			296			275			A+
Washington		67			48			163			278			262			AA
Massachusetts		46			8			169			223			204			AA
Arizona		—			7			170			177			165			AA
Michigan		—			—			132			132			122			AA-
Ohio		6			40			82			128			119			AA
All others		276			251			1,096			1,623			1,528			AA-
Total		$	580		$	891		$	3,478		$	4,949		$	4,619
Fair Value of Available-for-Sale Portfolio of
Obligations of State and Political Subdivisions
As of December 31, 2013 (1)
State		State			Local			Revenue Bonds			Fair			Amortized			Average
		General			General						Value			Cost			Credit
		Obligation			Obligation												Rating
		(in millions)
Texas		$	77		$	299		$	277		$	653		$	629		AA
New York		12			58			519			589			575			AA
California		32			86			354			472			452			A+
Florida		33			59			242			334			318			AA-
Illinois		14			70			156			240			234			A+
Massachusetts		44			16			147			207			200			AA
Washington		31			19			153			203			199			AA
Arizona		—			7			166			173			170			AA
Michigan		—			28			102			130			125			AA-
Georgia		13			18			97			128			128			A+
All others		254			228			943			1,425			1,381			AA-
Total		$	510		$	888		$	3,156		$	4,554		$	4,411		AA-
____________________
-1	Excludes $846 million and $525 million as of December 31, 2014 and 2013, respectively, of pre-refunded bonds, at fair value. The credit ratings are based on the underlying ratings and do not include any benefit from bond insurance.
The revenue bond portfolio is comprised primarily of essential service revenue bonds issued by transportation authorities and other utilities, water and sewer authorities, universities and healthcare providers.
Revenue Bonds
Sources of Funds
		As of December 31, 2014						As of December 31, 2013
Type		Fair			Amortized			Fair			Amortized
		Value			Cost			Value			Cost
		(in millions)
Transportation		$	796		$	733		$	642		$	615
Water and sewer		563			527			459			453
Tax backed		551			514			708			686
Higher education		527			492			358			353
Municipal utilities		512			479			500			482
Healthcare		346			317			289			281
All others		183			173			200			192
Total		$	3,478		$	3,235		$	3,156		$	3,062
The majority of the investment portfolio is managed by four outside managers. The Company has established detailed guidelines regarding credit quality, exposure to a particular sector and exposure to a particular obligor within a sector.
The following tables summarize, for all securities in an unrealized loss position, the aggregate fair value and gross unrealized loss by length of time the amounts have continuously been in an unrealized loss position.
Fixed-Maturity Securities
Gross Unrealized Loss by Length of Time
As of December 31, 2014
	Less than 12 months						12 months or more						Total
	Fair			Unrealized			Fair			Unrealized			Fair			Unrealized
	Value			Loss			Value			Loss			Value			Loss
	(dollars in millions)
Obligations of state and political subdivisions	$	64		$	0		$	25		$	(1	)	$	89		$	(1	)
U.S. government and agencies	139			0			68			(1		)	207			(1		)
Corporate securities	189			(3		)	104			(2		)	293			(5		)
Mortgage-backed securities:
RMBS	205			(3		)	159			(18		)	364			(21		)
CMBS	36			0			19			0			55			0
Asset-backed securities	56			(2		)	18			(1		)	74			(3		)
Foreign government securities	108			(2		)	0			0			108			(2		)
Total	$	797		$	(10	)	$	393		$	(23	)	$	1,190		$	(33	)
Number of securities(1)				125						82						198
Number of securities with other-than-temporary impairment				3						7						10
Fixed-Maturity Securities
Gross Unrealized Loss by Length of Time
As of December 31, 2013
	Less than 12 months						12 months or more						Total
	Fair			Unrealized			Fair			Unrealized			Fair			Unrealized
	Value			Loss			Value			Loss			Value			Loss
	(dollars in millions)
Obligations of state and political subdivisions	$	781		$	(39	)	$	5		$	0		$	786		$	(39	)
U.S. government and agencies	173			(6		)	—			—			173			(6		)
Corporate securities	401			(18		)	3			0			404			(18		)
Mortgage-backed securities:
RMBS	414			(21		)	186			(51		)	600			(72		)
CMBS	121			(4		)	—			—			121			(4		)
Asset-backed securities	196			(2		)	42			(5		)	238			(7		)
Foreign government securities	54			(1		)	1			0			55			(1		)
Total	$	2,140		$	(91	)	$	237		$	(56	)	$	2,377		$	(147	)
Number of securities				425						33						458
Number of securities with other-than-temporary impairment				13						11						24
___________________
-1	The number of securities does not add across because of lots of the same securities that have been purchased at different times and appear in both categories above (i.e., Less than 12 months and 12 months or more). If a security appears in both categories, it is counted only once in the Total column.
Of the securities in an unrealized loss position for 12 months or more as of December 31, 2014, three securities had unrealized losses greater than 10% of book value. The total unrealized loss for these securities as of December 31, 2014 was $15 million. The Company has determined that the unrealized losses recorded as of December 31, 2014 are yield related and not the result of other-than-temporary-impairment.
The amortized cost and estimated fair value of available-for-sale fixed-maturity securities by contractual maturity as of December 31, 2014 are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.
Distribution of Fixed-Maturity Securities
by Contractual Maturity
As of December 31, 2014
	Amortized			Estimated
	Cost			Fair Value
	(in millions)
Due within one year	$	111		$	112
Due after one year through five years	1,961			2,028
Due after five years through 10 years	2,286			2,422
Due after 10 years	3,720			3,985
Mortgage-backed securities:
RMBS	1,255			1,285
CMBS	639			659
Total	$	9,972		$	10,491
The investment portfolio contains securities that are either held in trust for the benefit of reinsurers in accordance with statutory requirements, placed on deposit to fulfill state licensing requirements, or otherwise restricted in the amount of $268 million and $396 million as of December 31, 2014 and December 31, 2013, respectively, based on fair value.
The fair value of the Company’s pledged securities to secure its obligations under its CDS exposure totaled $376 million and $677 million as of December 31, 2014 and December 31, 2013, respectively.
No material investments of the Company were non-income producing for years ended December 31, 2014 and 2013, respectively.
Internally Managed Portfolio
The investment portfolio tables shown above include both assets managed externally and internally. In the table below, more detailed information is provided for the component of the total investment portfolio that is internally managed (excluding short-term investments). The internally managed portfolio, as defined below, represents approximately 8% and 9% of the investment portfolio, on a fair value basis as of December 31, 2014 and December 31, 2013, respectively. The internally managed portfolio consists primarily of the Company's investments in securities for (i) loss mitigation purposes, (ii) other risk management purposes and (iii) where the Company believes a particular security presents an attractive investment opportunity.
One of the Company's strategies for mitigating losses has been to purchase securities it has insured that have expected losses, at discounted prices (assets purchased for loss mitigation purposes). In addition, the Company holds other invested assets that were obtained or purchased as part of negotiated settlements with insured counterparties or under the terms of our financial guaranties (other risk management assets).
Additional detail about the types and amounts of securities acquired by the Company for loss mitigation, other risk management and in the trading portfolio is set forth in the table below.
Internally Managed Portfolio
Carrying Value
	As of December 31,
	2014			2013
	(in millions)
Assets purchased for loss mitigation and other risk management purposes:
Fixed maturity securities	$	835		$	761
Other invested assets	46			82
Other	79			88
Total	$	960		$	931

Insurance_Company_Regulatory_R

Insurance Company Regulatory Requirements

12 Months Ended

Dec. 31, 2014

Insurance Company Regulatory Requirements [Abstract]

Insurance Company Regulatory Requirements

Insurance Company Regulatory Requirements

Each of the Company's insurance companies' ability to pay dividends depends, among other things, upon their financial condition, results of operations, cash requirements, compliance with rating agency requirements, and is also subject to restrictions contained in the insurance laws and related regulations of their state of domicile and other states. Financial statements prepared in accordance with accounting practices prescribed or permitted by local insurance regulatory authorities differ in certain respects from GAAP.

The Company's U.S. domiciled insurance companies prepare statutory financial statements in accordance with accounting practices prescribed or permitted by the National Association of Insurance Commissioners (“NAIC”) and their respective insurance departments. Prescribed statutory accounting practices are set forth in the NAIC Accounting Practices and Procedures Manual. The Company has no permitted accounting practices on a statutory basis.

GAAP differs in certain significant respects from U.S. insurance companies' statutory accounting practices prescribed or permitted by insurance regulatory authorities. The principal differences result from the following statutory accounting practices:

•

upfront premiums are earned when related principal and interest have expired rather than earned over the expected period of coverage;

•

acquisition costs are charged to expense as incurred rather than over the period that related premiums are earned;

•

a contingency reserve is computed based on statutory requirements, but no such reserve is required under GAAP;

•

certain assets designated as “non-admitted assets” are charged directly to statutory surplus, but are reflected as assets under GAAP;

•

investments in subsidiaries are carried on the balance sheet on the equity basis, to the extent admissible, rather than consolidated with the parent;

•

the amount of deferred tax assets that may be admitted is subject to an adjusted surplus threshold and is generally limited to the lesser of those assets the Company expects to realize within three years of the balance sheet date or fifteen percent of the Company's adjusted surplus. This realization period and surplus percentage is subject to change based on the amount of adjusted surplus. Under GAAP there is no non-admitted asset determination, rather a valuation allowance is recorded to reduce the deferred tax asset to an amount that is more likely than not to be realized;

•

insured credit derivatives are accounted for as insurance contracts rather than as derivative contracts measured at fair value;

•

bonds are generally carried at amortized cost rather than fair value;

•

VIEs and refinancing vehicles are not consolidated;

•

surplus notes are recognized as surplus and each payment of principal and interest is recorded only upon approval of the insurance regulator rather than liabilities with periodic accrual of interest;

•

push-down acquisition accounting is not applicable under statutory accounting practices, as it is under GAAP;

•

expected losses are discounted at a rate of 4.5% or 5.0%, recorded when the loss is deemed probable and without consideration of the deferred premium revenue rather than discounted at the risk free rate at the end of each reporting period and only to the extent they exceed deferred premium revenue;

•

the present value of installment premiums and commissions are not recorded on the balance sheet as they are under GAAP.

AG Re, a Bermuda regulated Class 3B insurer, prepares its statutory financial statements in conformity with the accounting principles set forth in the Insurance Act 1978, amendments thereto and related regulations. GAAP differs in certain significant respects from statutory accounting practices prescribed or permitted by Bermuda insurance regulatory authorities. The principal differences result from the following statutory accounting practices:

•

acquisition costs on upfront premiums are charged to operations as incurred, rather than over the period that related premiums are earned;

•

certain assets designated as “non-admitted assets” are charged directly to statutory surplus rather than reflected as assets under GAAP;

•

insured credit derivatives are accounted for as insurance contracts (except that loss reserves on insured credit derivatives are not net of unearned premium reserve), rather than as derivative contracts measured at fair value;

•

Loss reserves on non derivative contracts are net of unearned premium, which is offset by deferred acquisition costs, rather than only unearned premium. Loss reserves include a statutory reserve which includes a discount safety margin and statutory catastrophe reserve.

Insurance Regulatory Amounts Reported

Policyholders' Surplus

Net Income (Loss)

As of December 31,

Year Ended December 31,

2014

2013

2014

2013

2012

(in millions)

U.S. statutory companies:

AGM(1)

$

2,267

$

1,733

$

304

$

340

$

203

MAC

$

612

$

514

$

75

$

26

$

1

AGC(1)

1,086

693

116

211

31

Bermuda statutory company:

AG Re

1,114

1,119

28

103

117

____________________

-1

Policyholders' surplus of AGM and AGC include their indirect share of MAC. AGM and AGC own approximately 61% and 39%, respectively, of the outstanding stock of Municipal Assurance Holdings Inc. ("MAC Holdings"), which owns 100% of the outstanding common stock of MAC.

On July 16, 2013, the Company completed a series of transactions that increased the capitalization of MAC to $800 million on a statutory basis. The Company does not currently anticipate that MAC will distribute any dividends.

AGM and its subsidiaries Assured Guaranty Municipal Insurance Company ("AGMIC") and Assured Guaranty (Bermuda) Ltd. ("AGBM") terminated the reinsurance pooling agreement pursuant to which AGMIC and AGBM had assumed a quota share percentage of the financial guaranty insurance policies issued by AGM, and AGM reassumed such ceded business. Subsequently, AGMIC was merged into AGM, with AGM as the surviving company.

AGBM, which had made a loan of $82.5 million to AGUS, an indirect parent holding company of AGM, received all of the outstanding shares of MAC held by AGUS and cash, in full satisfaction of the principal of and interest on such loan. After AGBM distributed substantially all of its assets, including the MAC shares, to AGM as a dividend, AGM sold AGBM to its affiliate AG Re. Subsequently, AGBM and AG Re merged, with AG Re as the surviving company. The sale of AGBM to, and subsequent merger with, AG Re were each effective as of July 17, 2013.

MAC Holdings, was formed to own 100% of the outstanding stock of MAC. AGM and its affiliate AGC subscribed for approximately 61% and 39% of the outstanding MAC Holdings common stock, respectively, for which AGM paid $425 million and AGC paid $275 million, as consideration. The consideration consisted of all of MAC's outstanding common stock (in the case of AGM), cash and marketable securities.

MAC Holdings then contributed cash and marketable securities having a fair market value sufficient to increase MAC's policyholders' surplus to approximately $400 million, and purchased a surplus note issued by MAC in the principal amount of $300 million. In addition, AGM purchased a surplus note issued by MAC in the principal amount of $100 million.

Following the increase in MAC's capitalization, AGM ceded par exposure of approximately $87 billion and unearned premiums of approximately $468 million to MAC, and AGC ceded par exposure of approximately $24 billion and unearned premiums of approximately $249 million to MAC.

In addition, on July 15, 2013, AGM and its wholly-owned subsidiary, AGE (together, the "AGM Group") were notified that the New York State Department of Financial Services ("NYDFS") does not object to the AGM Group reassuming contingency reserves that they had ceded to AG Re and electing to cease ceding future contingency reserves to AG Re under the following circumstances:

•

The AGM Group may reassume 33% of a contingency reserve base of approximately $250 million (the “NY Contingency Reserve Base”) in 2013, after July 16, 2013, the date on which the transactions for the capitalization of MAC were completed (the “Closing Date”).

•

The AGM Group may reassume 50% of the NY Contingency Reserve Base in 2014, no earlier than the one year anniversary of the Closing Date, with the prior approval of the NYDFS.

•

The AGM Group may reassume the remaining 17% of the NY Contingency Reserve Base in 2015, no earlier than the two year anniversary of the Closing Date, with the prior approval of the NYDFS.

At the same time, AGC was notified that the Maryland Insurance Administration ("MIA") does not object to AGC reassuming contingency reserves that it had ceded to AG Re and electing to cease ceding future contingency reserves to AG Re under the following circumstances:

•

AGC may reassume 33% of a contingency reserve base of approximately $267 million (the “MD Contingency Reserve Base”) in 2013, after the Closing Date.

•

AGC may reassume 50% of the MD Contingency Reserve Base in 2014, no earlier than the one year anniversary of the Closing Date, with the prior approval of the MIA and the NYDFS.

•

AGC may reassume the remaining 17% of the MD Contingency Reserve Base in 2015, no earlier than the two year anniversary of the Closing Date, with the prior approval of the MIA and the NYDFS.

The reassumption of the contingency reserves has the effect of increasing contingency reserves by the amount reassumed and decreasing policyholders' surplus by the same amount; there would be no impact on the statutory or rating agency capital as a result of the reassumption. The reassumption of contingency reserves would permit the release of amounts from the AG Re trust accounts securing AG Re's reinsurance of the AGM Group and AGC.

In the third quarter of 2013, AGM and AGC reassumed 33% of their respective contingency reserve bases, which permitted the release of approximately $130 million of assets from the AG Re trust accounts securing AG Re's reinsurance of AGM and AGC, after adjusting for increases in the amounts required to be held in such accounts due to changes in asset values.

In the third quarter of 2014, AGM and AGC reassumed 50% of their respective contingency reserve bases (approximately $244 million in the aggregate). In addition, in the fourth quarter of 2014, AGE reassumed 83% (representing the first and second installments of the approved reassumption) of its portion of the NY Contingency Reserve Base (approximately $24.5 million in the aggregate). These 2014 reassumptions collectively permitted the release of approximately $274 million of assets from the AG Re trust accounts securing AG Re's reinsurance of the AGM Group and AGC, after taking into account other, normal-course adjustments to AG Re’s collateral requirements such as changes in asset values and changes in assumed reserves.

From time to time, AGM and AGC have obtained approval from their regulators to release contingency reserves based on losses or because the accumulated reserve is deemed excessive in relation to the insurer's outstanding insured obligations.  In 2014, on the latter basis, AGM obtained NYDFS approval for a contingency reserve release of approximately $588 million and AGC obtained MIA approval for a contingency reserve release of approximately $540 million.

Dividend Restrictions and Capital Requirements

Under New York insurance law, AGM may only pay dividends out of "earned surplus", which is the portion of a company's surplus that represents the net earnings, gains or profits (after deduction of all losses) that have not been distributed to shareholders as dividends or transferred to stated capital or capital surplus, or applied to other purposes permitted by law, but does not include unrealized appreciation of assets. AGM may pay dividends without the prior approval of the New York Superintendent of Financial Services ("New York Superintendent") that, together with all dividends declared or distributed by it during the preceding 12 months, does not exceed the lesser of 10% of its policyholders' surplus (as of the last annual or quarterly statement filed with the New York Superintendent) or 100% of its adjusted net investment income during that period. The maximum amount available during 2015 for AGM to distribute as dividends without regulatory approval, after giving effect to dividends paid in the prior 12 months, is estimated to be approximately $227 million, of which approximately $67 million is available for distribution in the first quarter of 2015.

Under Maryland's insurance law, AGC may, with prior notice to the Maryland Insurance Commissioner, pay an ordinary dividend that, together with all dividends paid in the prior 12 months, does not exceed 10% of its policyholders' surplus (as of the prior December 31) or 100% of its adjusted net investment income during that period. The maximum amount available during 2015 for AGC to distribute as ordinary dividends will be approximately $90 million, of which approximately $21 million is available for distribution in the first quarter of 2015, after giving effect to dividends paid in the prior 12 months.

MAC is subject to the same dividend limitations described above for AGM. The Company does not currently anticipate that MAC will distribute any dividends.

Any distribution (including repurchase of shares) of any share capital, contributed surplus or other statutory capital) that would reduce AG Re's total statutory capital by 15% or more of its total statutory capital as set out in its previous year's financial statements requires the prior approval of the Authority. Separately, dividends are paid out of an insurer's statutory surplus and cannot exceed that surplus. Further, annual dividends cannot exceed 25% of total statutory capital and surplus, which is $279 million, without AG Re certifying to the Bermuda Monetary Authority that it will continue to meet required margins. Based on the foregoing limitations, in 2015 AG Re has the capacity to (i) make capital distributions in an aggregate amount up to $127 million without the prior approval of the Authority and (ii) declare and pay dividends in an aggregate amount up to the limit of its outstanding statutory surplus, which is $271 million. Such dividend capacity is further limited by the actual amount of AG Re’s unencumbered assets, which amount changes from time to time due in part to collateral posting requirements. As of December 31, 2014, AG Re had unencumbered assets of approximately $651 million.

U.K. company law prohibits each of AGE and AGUK from declaring a dividend to its shareholders unless it has “profits available for distribution.” The determination of whether a company has profits available for distribution is based on its accumulated realized profits less its accumulated realized losses. While the U.K. insurance regulatory laws impose no statutory restrictions on a general insurer's ability to declare a dividend, the Prudential Regulation Authority's capital requirements may in practice act as a restriction on dividends. The Company does not expect AGE or AGUK to distribute any dividends at this time

Dividends and Surplus Notes

By Insurance Company Subsidiaries

Year Ended December 31,

2014

2013

2012

(in millions)

Dividends paid by AGC to AGUS

$

69

$

67

$

55

Dividends paid by AGM to AGMH

160

163

30

Dividends paid by AG Re to AGL

82

144

151

Repayment of surplus note by AGM to AGMH

50

50

50

Issuance of surplus notes by MAC to MAC Holdings

—

(300

)

—

Issuance of surplus notes by MAC to AGM

—

(100

)

—

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	Accounting Policy
	The provision for income taxes consists of an amount for taxes currently payable and an amount for deferred taxes. Deferred income taxes are provided for temporary differences between the financial statement carrying amounts and tax bases of assets and liabilities, using enacted rates in effect for the year in which the differences are expected to reverse. A valuation allowance is recorded to reduce the deferred tax asset to an amount that is more likely than not to be realized.
	Non-interest‑bearing tax and loss bonds are purchased in the amount of the tax benefit that results from deducting contingency reserves as provided under Internal Revenue Code Section 832(e). The Company records the purchase of tax and loss bonds in deferred taxes.
	The Company recognizes tax benefits only if a tax position is “more likely than not” to prevail.
	Overview
	AGL, and its "Bermuda Subsidiaries," which consist of AG Re, AGRO, and Cedar Personnel Ltd., are not subject to any income, withholding or capital gains taxes under current Bermuda law. The Company has received an assurance from the Minister of Finance in Bermuda that, in the event of any taxes being imposed, AGL and its Bermuda Subsidiaries will be exempt from taxation in Bermuda until March 31, 2035. AGL's U.S. and U.K. subsidiaries are subject to income taxes imposed by U.S. and U.K. authorities, respectively, and file applicable tax returns. In addition, AGRO, a Bermuda domiciled company and AGE, a U.K. domiciled company, have elected under Section 953(d) of the U.S. Internal Revenue Code to be taxed as a U.S. domestic corporation.
	In November 2013, AGL became tax resident in the U.K. although it will remain a Bermuda-based company and its administrative and head office functions will continue to be carried on in Bermuda. As a company that is not incorporated in the U.K., AGL currently intends to manage the affairs of AGL in such a way as to establish and maintain its status as a company that is tax resident in the U.K. As a U.K. tax resident company, AGL is required to file a corporation tax return with Her Majesty’s Revenue & Customs (“HMRC”).  AGL is subject to U.K. corporation tax in respect of its worldwide profits (both income and capital gains), subject to any applicable exemptions. The main rate of corporation tax is 21% currently; such rate fell to 21% as of April 1, 2014 and will fall to 20% as of April 1, 2015. AGL has also registered in the U.K. to report its Value Added Tax (“VAT”) liability.  The current rate of VAT is 20%. Assured Guaranty does not expect that becoming U.K. tax resident will result in any material change in the group’s overall tax charge. Assured Guaranty expects that the dividends AGL receives from its direct subsidiaries will be exempt from U.K. corporation tax due to the exemption in section 931D of the U.K. Corporation Tax Act 2009.  In addition, any dividends paid by AGL to its shareholders should not be subject to any withholding tax in the U.K.  The U.K. government implemented a new tax regime for “controlled foreign companies” (“CFC regime”) effective January 1, 2013.  Assured Guaranty does not expect any profits of non-U.K. resident members of the group to be taxed under the CFC regime and has obtained a clearance from HMRC confirming this on the basis of current facts.
	For the periods beginning on July 1, 2009 and forward, AGMH files a consolidated federal income tax return with AGUS, AGC, AG Financial Products Inc. ("AGFP") and AG Analytics Inc. (“AGUS consolidated tax group”). Beginning on May 12, 2012, MAC also joined the AGUS consolidated tax group. Assured Guaranty Overseas US Holdings Inc. and its subsidiaries AGRO and AG Intermediary Inc., file their own consolidated federal income tax return.
	Provision for Income Taxes
	The effective tax rates reflect the proportion of income recognized by each of the Company’s operating subsidiaries, with U.S. subsidiaries taxed at the U.S. marginal corporate income tax rate of 35%, U.K. subsidiaries taxed at the U.K. blended marginal corporate tax rate of 21.5% unless subject to U.S. tax by election or as a U.S. controlled foreign corporation, and no taxes for the Company’s Bermuda subsidiaries unless subject to U.S. tax by election or as a U.S. controlled foreign corporation. For periods subsequent to April 1, 2014, the U.K. corporation tax rate has been reduced to 21%, for the period April 1, 2013 to April 1, 2014 the U.K. corporation tax rate was 23% resulting in a blended tax rate of 21.5% in 2014, and prior to April 1, 2013, the U.K. corporation tax rate was 24% resulting in a blended tax rate of 23.25% in 2013. The Company’s overall effective tax rate fluctuates based on the distribution of income across jurisdictions.
	A reconciliation of the difference between the provision for income taxes and the expected tax provision at statutory rates in taxable jurisdictions is presented below.
	Effective Tax Rate Reconciliation
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Expected tax provision (benefit) at statutory rates in taxable jurisdictions	$	490		$	390		$	76
	Tax-exempt interest	(53		)	(57		)	(61		)
	Change in liability for uncertain tax positions	9			(2		)	2
	Other	(3		)	3			5
	Total provision (benefit) for income taxes	$	443		$	334		$	22
	Effective tax rate	28.9		%	29.2		%	16.5		%
	The expected tax provision at statutory rates in taxable jurisdictions is calculated as the sum of pretax income in each jurisdiction multiplied by the statutory tax rate of the jurisdiction by which it will be taxed. Pretax income of the Company’s subsidiaries which are not U.S. or U.K. domiciled but are subject to U.S. or U.K. tax by election, establishment of tax residency or as controlled foreign corporations, are included at the U.S. or U.K. statutory tax rate. Where there is a pretax loss in one jurisdiction and pretax income in another, the total combined expected tax rate may be higher or lower than any of the individual statutory rates.
	The following table presents pretax income and revenue by jurisdiction.
	Pretax Income (Loss) by Tax Jurisdiction
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	United States	$	1,420		$	1,118		$	218
	Bermuda	142			27			(86		)
	U.K.	(31		)	(3		)	0
	Total	$	1,531		$	1,142		$	132
	Revenue by Tax Jurisdiction
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	United States	$	1,633		$	1,389		$	875
	Bermuda	365			219			79
	U.K.	(4		)	0			0
	Total	$	1,994		$	1,608		$	954
	Pretax income by jurisdiction may be disproportionate to revenue by jurisdiction to the extent that insurance losses incurred are disproportionate.
	Components of Net Deferred Tax Assets
		As of December 31,
		2014			2013
		(in millions)
	Deferred tax assets:
	Unrealized losses on credit derivative financial instruments, net	$	224		$	402
	Unearned premium reserves, net	63			63
	Loss and LAE reserve	66			134
	Tax and loss bonds	39			33
	Alternative minimum tax credit	57			90
	Foreign tax credit	—			37
	FG VIEs	13			29
	DAC	35			40
	Investment basis difference	104			93
	Deferred compensation	38			33
	Other	19			21
	Total deferred income tax assets	658			975
	Deferred tax liabilities:
	Contingency reserves	64			47
	Public debt	96			98
	Unrealized appreciation on investments	159			68
	Unrealized gains on CCS	22			16
	Market discount	36			24
Other	21			34
Total deferred income tax liabilities	398			287
Net deferred income tax asset	$	260		$	688
As of December 31, 2014, the Company had alternative minimum tax credits of $57 million which do not expire. Management believes sufficient future taxable income exists to realize the full benefit of these tax credits.
As of December 31, 2014, AGRO had a stand-alone net operating loss ("NOL") of $6 million, compared with $13 million as of December 31, 2013, which is available through 2023 to offset its future U.S. taxable income. AGRO's stand alone NOL may not offset the income of any other members of AGRO's consolidated group with very limited exceptions and the Internal Revenue Code limits the amounts of NOL that AGRO may utilize each year.
Valuation Allowance
The Company came to the conclusion that it is more likely than not that its net deferred tax asset will be fully realized after weighing all positive and negative evidence available as required under GAAP. The positive evidence that was considered included the cumulative operating income the Company has earned over the last three years, and the significant unearned premium income to be included in taxable income. The positive evidence outweighs any negative evidence that exists. As such, the Company believes that no valuation allowance is necessary in connection with this deferred tax asset. The Company will continue to analyze the need for a valuation allowance on a quarterly basis.
Audits
AGUS has open tax years with the U.S. Internal Revenue Service (“IRS”) for 2009 forward and is currently under audit for the 2009-2012 tax years. The IRS concluded its field work with respect to tax years 2006 through 2008 without adjustment. On February 20, 2013 the IRS notified AGUS that the Joint Committee on Taxation completed its review of the 2006 through 2008 tax years and has accepted the results of the IRS examination without exception. Assured Guaranty Oversees US Holdings Inc. has open tax years of 2010 forward. The IRS concluded its field work with respect to tax year through 2009 for AGMH and subsidiaries while members of the Dexia Holdings Inc. consolidated tax group without adjustment. The Company's U.K. subsidiaries are not currently under examination and have open tax years of 2012 forward.
Uncertain Tax Positions
The following table provides a reconciliation of the beginning and ending balances of the total liability for unrecognized tax benefits. The Company does not believe it is reasonably possible that this amount will change significantly in the next twelve months.
	2014			2013			2012
	(in millions)
Balance as of January 1,	$	20		$	22		$	20
True-up from tax return filings	6			4			—
Increase in unrecognized tax benefits as a result of position taken during the current period	2			3			2
Decrease due to closing of IRS audit	—			(9		)	—
Balance as of December 31,	$	28		$	20		$	22
The Company's policy is to recognize interest and penalties related to uncertain tax positions in income tax expense and has accrued approximately $1 million per year from 2012 to 2014. As of December 31, 2014 and December 31, 2013, the Company has accrued $4.5 million and $3.5 million of interest, respectively.
The total amount of unrecognized tax benefits as of December 31, 2014, that would affect the effective tax rate, if recognized, was $28 million.
Liability For Tax Basis Step-Up Adjustment
In connection with the Company's initial public offering, the Company and ACE Financial Services Inc. (“AFS”), a subsidiary of ACE Limited, entered into a tax allocation agreement, whereby the Company and AFS made a “Section 338 (h)(10)” election that has the effect of increasing the tax basis of certain affected subsidiaries' tangible and intangible assets to fair value. Future tax benefits that the Company derives from the election will be payable to AFS when realized by the Company.
As a result of the election, the Company has adjusted its net deferred tax liability, to reflect the new tax basis of the Company's affected assets. The additional basis is expected to result in increased future income tax deductions and, accordingly, may reduce income taxes otherwise payable by the Company. Any tax benefit realized by the Company will be paid to AFS. Such tax benefits will generally be calculated by comparing the Company's affected subsidiaries' actual taxes to the taxes that would have been owed by those subsidiaries had the increase in basis not occurred. After a 15 year period which ends in 2019, to the extent there remains an unrealized tax benefit, the Company and AFS will negotiate a settlement of the unrealized benefit based on the expected realization at that time.
As of December 31, 2014 and December 31, 2013, the liability for tax basis step-up adjustment, which is included in the Company's balance sheets in “Other liabilities,” was $4 million and $5 million, respectively. The Company has paid ACE Limited and correspondingly reduced its liability by $1 million in 2014.
Tax Treatment of CDS
The Company treats the guaranty it provides on CDS as an insurance contract for tax purposes and as such a taxable loss does not occur until the Company expects to make a loss payment to the buyer of credit protection based upon the occurrence of one or more specified credit events with respect to the contractually referenced obligation or entity. The Company holds its CDS to maturity, at which time any unrealized fair value loss in excess of credit-related losses would revert to zero. The tax treatment of CDS is an unsettled area of the law. The uncertainty relates to the IRS determination of the income or potential loss associated with CDS as either subject to capital gain (loss) or ordinary income (loss) treatment. In treating CDS as insurance contracts the Company treats both the receipt of premium and payment of losses as ordinary income and believes it is more likely than not that any CDS credit related losses will be treated as ordinary by the IRS. To the extent the IRS takes the view that the losses are capital losses in the future and the Company incurred actual losses associated with the CDS, the Company would need sufficient taxable income of the same character within the carryback and carryforward period available under the tax law.

Reinsurance_and_Other_Monoline

Reinsurance and Other Monoline Exposures	12 Months Ended
	Dec. 31, 2014
Insurance [Abstract]
Reinsurance and Other Monoline Exposures	Reinsurance and Other Monoline Exposures
	The Company assumes exposure on insured obligations (“Assumed Business”) and cedes portions of its exposure on obligations it has insured (“Ceded Business”) in exchange for premiums, net of ceding commissions. The Company has historically entered into ceded reinsurance contracts in order to obtain greater business diversification and reduce the net potential loss from large risks.
	Accounting Policy
	For business assumed and ceded, the accounting model of the underlying direct financial guaranty contract dictates the accounting model used for the reinsurance contract (except for those eliminated as FG VIEs). For any assumed or ceded financial guaranty insurance premiums, the accounting model described in Note 4 is followed, for assumed and ceded financial guaranty insurance losses, the accounting model in Note 7 is followed. For any assumed or ceded credit derivative contracts, the accounting model in Note 9 is followed.
	Assumed and Ceded Business
	The Company assumes business from other monoline financial guaranty companies. Under these relationships, the Company assumes a portion of the ceding company’s insured risk in exchange for a premium. The Company may be exposed to risk in this portfolio in that the Company may be required to pay losses without a corresponding premium in circumstances where the ceding company is experiencing financial distress and is unable to pay premiums. The Company’s facultative and treaty agreements are generally subject to termination at the option of the ceding company:
	•	if the Company fails to meet certain financial and regulatory criteria and to maintain a specified minimum financial strength rating, or
	•	upon certain changes of control of the Company.
	Upon termination under these conditions, the Company may be required (under some of its reinsurance agreements) to return to the ceding company unearned premiums (net of ceding commissions) and loss reserves calculated on a statutory basis of accounting, attributable to reinsurance assumed pursuant to such agreements after which the Company would be released from liability with respect to the Assumed Business.
	Upon the occurrence of the conditions set forth in the first bullet above, whether or not an agreement is terminated, the Company may be required to obtain a letter of credit or alternative form of security to collateralize its obligation to perform under such agreement or it may be obligated to increase the level of ceding commission paid.
	The downgrade of the financial strength ratings of AG Re or of AGC gives certain reinsurance counterparties the right to recapture ceded business, which would lead to a reduction in the Company's unearned premium reserve and related earnings on such reserve. With respect to a significant portion of the Company's in-force financial guaranty assumed business, based on AG Re's and AGC's current ratings and subject to the terms of each reinsurance agreement, the third party ceding company may have the right to recapture assumed business ceded to AG Re and/or AGC, and in connection therewith, to receive payment from the assuming reinsurer of an amount equal to the reinsurer’s statutory unearned premium (net of ceding commissions) and statutory loss reserves (if any) associated with that business, plus, in certain cases, an additional ceding commission. As of December 31, 2014, if each third party company ceding business to AG Re and/or AGC had a right to recapture such business, and chose to exercise such right, the aggregate amounts that AG Re and AGC could be required to pay to all such companies would be approximately $85 million and $45 million, respectively.
	The Company has Ceded Business to non-affiliated companies to limit its exposure to risk. Under these relationships, the Company cedes a portion of its insured risk in exchange for a premium paid to the reinsurer. The Company remains primarily liable for all risks it directly underwrites and is required to pay all gross claims. It then seeks reimbursement from the reinsurer for its proportionate share of claims. The Company may be exposed to risk for this exposure if it were required to pay the gross claims and not be able to collect ceded claims from an assuming company experiencing financial distress. A number of the financial guaranty insurers to which the Company has ceded par have experienced financial distress and been downgraded by the rating agencies as a result. In addition, state insurance regulators have intervened with respect to some of these insurers. The Company’s ceded contracts generally allow the Company to recapture Ceded Business after certain triggering events, such as reinsurer downgrades.
	Over the past several years, the Company has entered into several commutations in order to reassume previously ceded books of business from its reinsurers. The Company has also canceled assumed reinsurance contracts.
	Net Effect of Commutations of Ceded and
	Cancellations of Assumed Reinsurance Contracts
		Year Ended December 31,
		2014				2013				2012
		(in millions)
	Increase (decrease) in net unearned premium reserve	$	20			$	11			$	109
	Increase (decrease) in net par outstanding	1,167				151				19,173
	Commutation gains recorded in other income	23				2				82
	The following table presents the components of premiums and losses reported in the consolidated statement of operations and the contribution of the Company's Assumed and Ceded Businesses.
	Effect of Reinsurance on Statement of Operations
		Year Ended December 31,
		2014				2013				2012
		(in millions)
	Premiums Written:
	Direct	$	116			$	106			244
	Assumed(1)	(12		)		17				9
	Ceded(2)	15				2				51
	Net	$	119			$	125			304
	Premiums Earned:
	Direct	$	581			$	819			936
	Assumed	47				40				50
	Ceded	(58		)		(107		)		(133	)
	Net	$	570			$	752			853
	Loss and LAE:
	Direct	$	132			$	110			636
	Assumed	37				73				(4	)
	Ceded	(43		)		(29		)		(128	)
	Net	$	126			$	154			504
	____________________
	-1	Negative assumed premiums written were due to cancellations and changes in expected Debt Service schedules.
	-2	Positive ceded premiums written were due to commutations and changes in expected Debt Service schedules.
	On January 24, 2012, AGC reinsured approximately $1.8 billion of U.S. public finance par from Radian Asset. In connection with the reinsurance assumption, the Company received a payment of $22 million.
	Reinsurer Exposure
	In addition to assumed and ceded reinsurance arrangements, the Company may also have exposure to some financial guaranty reinsurers (i.e., monolines) in other areas. Second-to-pay insured par outstanding represents transactions the Company has insured that were previously insured by other monolines. The Company underwrites such transactions based on the underlying insured obligation without regard to the primary insurer. Another area of exposure is in the investment portfolio where the Company holds fixed-maturity securities that are wrapped by monolines and whose value may decline based on the rating of the monoline. As of December 31, 2014, based on fair value, the Company had fixed-maturity securities in its investment portfolio consisting of $330 million insured by National Public Finance Guarantee Corporation, $266 million insured by Ambac Assurance Corporation ("Ambac") and $29 million insured by other guarantors.
	Exposure by Reinsurer
			Ratings at				Par Outstanding (1)
			February 24, 2015				As of December 31, 2014
	Reinsurer		Moody’s		S&P		Ceded Par				Second-to-				Assumed Par
			Reinsurer		Reinsurer		Outstanding				Pay Insured				Outstanding
			Rating		Rating						Par
											Outstanding
			(dollars in millions)
	American Overseas Reinsurance Company Limited (f/k/a Ram Re)		WR (2)		WR		$	6,727			$	—			$	30
	Tokio Marine & Nichido Fire Insurance Co., Ltd. (“Tokio”)		Aa3 (3)		AA- (3)		5,276				—				—
	Radian Asset		Ba1		B+		4,104				21				671
	Syncora Guarantee Inc.		WR		WR		3,715				1,514				161
	Mitsui Sumitomo Insurance Co. Ltd.		A1		A+ (3)		2,033				—				—
	ACA Financial Guaranty Corp.		NR (5)		WR		746				2				—
	Swiss Reinsurance Co.		Aa3		AA-		93				—				—
	Ambac		WR		WR		82				4,930				14,342
	National Public Finance Guarantee Corporation		A3		AA-		—				6,210				5,894
MBIA		-4		-4		—				2,613				587
FGIC		WR		WR		—				2,074				834
Ambac Assurance Corp. Segregated Account		NR		NR		—				109				956
CIFG Assurance North America Inc. ("CIFG")		WR		WR		—				102				4,365
Other		Various		Various		199				894				46
Total						$	22,975			$	18,469			$	27,886
____________________
-1	Includes par related to insured credit derivatives.
(2)    Represents “Withdrawn Rating.”
(3)    The Company has structural collateral agreements satisfying the triple-A credit requirement of S&P and/or Moody’s.
-4	MBIA includes subsidiaries MBIA Insurance Corp. rated B by S&P and B2 by Moody's and MBIA U.K. Insurance Ltd. rated B by S&P and Ba2 by Moody’s.
-5	Represents “Not Rated.”
Ceded Par Outstanding by Reinsurer and Credit Rating
As of December 31, 2014
			Internal Credit Rating
Reinsurer			AAA				AA				A				BBB				BIG				Total
			(in millions)
American Overseas Reinsurance Company Limited (f/k/a Ram Re)			$	633			$	2,452			$	1,992			$	1,158			$	492			$	6,727
Tokio			763				968				1,485				1,281				779				5,276
Radian Asset			206				287				2,037				1,085				489				4,104
Syncora Guarantee Inc.			—				291				498				2,193				733				3,715
Mitsui Sumitomo Insurance Co. Ltd.			134				669				742				299				189				2,033
ACA Financial Guaranty Corp			—				458				277				11				—				746
Swiss Reinsurance Co.			—				—				0				26				67				93
Ambac			—				—				82				—				—				82
Other			62				82				55				—				—				199
Total			$	1,798			$	5,207			$	7,168			$	6,053			$	2,749			$	22,975
In accordance with U.S. statutory accounting requirements and U.S. insurance laws and regulations, in order for the Company to receive credit for liabilities ceded to reinsurers domiciled outside of the U.S., such reinsurers must secure their liabilities to the Company. All of the unauthorized reinsurers in the table above are required to post collateral for the benefit of the Company in an amount at least equal to the sum of their ceded unearned premium reserve, loss reserves and contingency reserves all calculated on a statutory basis of accounting. In addition, certain authorized reinsurers in the table above post collateral on terms negotiated with the Company. Collateral may be in the form of letters of credit or trust accounts. The total collateral posted by all non-affiliated reinsurers as of December 31, 2014 is approximately $610 million.
Second-to-Pay
Insured Par Outstanding by Internal Rating
As of December 31, 2014(1)
	Public Finance																				Structured Finance
	AAA				AA				A				BBB				BIG				AAA				AA		A		BBB		BIG		Total
	(in millions)
Radian Asset	$	—			$	—			$	3			$	12			$	6			$	—			$	—	$	—	$	—	$	—	$	21
Syncora Guarantee Inc.	—				45				326				727				276				96				—		—		—		44		1,514
ACA Financial Guaranty Corp.	—				1				—				1				—				—				—		—		—		—		2
Ambac	30				1,301				2,597				637				63				—				1		64		231		6		4,930
National Public Finance Guarantee Corporation	160				2,193				3,833				—				—				—				—		24		—		—		6,210
MBIA	—				65				254				424				—				—				1,508		—		243		119		2,613
FGIC	—				77				975				281				302				371				—		25		—		43		2,074
Ambac Assurance Corp. Segregated Account	—				—				—				—				—				—				33		—		—		76		109
CIFG	—				4				51				22				25				—				—		—		—		—		102
Other	—				894				—				—				—				—				—		—		—		—		894
Total	$	190			$	4,580			$	8,039			$	2,104			$	672			$	467			$	1,542	$	113	$	474	$	288	$	18,469
____________________
-1	Assured Guaranty’s internal rating.
Amounts Due (To) From Reinsurers
As of December 31, 2014
	Assumed				Ceded				Assumed				Ceded
	Premium, net				Premium, net				Expected				Expected
	of Commissions				of Commissions				Loss and LAE				Loss and LAE
	(in millions)
American Overseas Reinsurance Company Limited (f/k/a Ram Re)	$	—			$	(8	)		$	—			$	11
Tokio	—				(13		)		—				46
Radian Asset	—				(13		)		—				19
Syncora Guarantee Inc.	—				(29		)		—				4
Mitsui Sumitomo Insurance Co. Ltd.	—				(3		)		—				15
Swiss Reinsurance Co.	—				(3		)		—				6
Ambac	43				—				(19		)		—
National Public Finance Guarantee Corporation	7				—				(7		)		—
MBIA	5				—				(9		)		—
FGIC	5				—				(3		)		—
Ambac Assurance Corp. Segregated Account	13				—				(83		)		—
CIFG	—				—				(6		)		—
Other	(2		)		(23		)		—				—
Total	$	71			$	(92	)		$	(127	)		$	101
Excess of Loss Reinsurance Facility
AGC, AGM and MAC entered into an aggregate excess of loss reinsurance facility with a number of reinsurers, effective as of January 1, 2014. The facility covers losses occurring either from January 1, 2014 through December 31, 2021, or January 1, 2015 through December 31, 2022, at the option of AGC, AGM and MAC. It terminates on January 1, 2016, unless AGC, AGM and MAC choose to extend it. The facility covers certain U.S. public finance credits insured or reinsured by AGC, AGM and MAC as of September 30, 2013, excluding credits that were rated non-investment grade as of December 31, 2013 by Moody’s or S&P or internally by AGC, AGM or MAC and is subject to certain per credit limits. Among the credits excluded are those associated with the Commonwealth of Puerto Rico and its related authorities and public corporations. The facility attaches when AGC’s, AGM’s and MAC’s net losses (net of AGC’s and AGM's reinsurance (including from affiliates) and net of recoveries) exceed $1.5 billion in the aggregate. The facility covers a portion of the next $500 million of losses, with the reinsurers assuming pro rata in the aggregate $450 million of the $500 million of losses and AGC, AGM and MAC jointly retaining the remaining $50 million of losses. The reinsurers are required to be rated at least AA- or to post collateral sufficient to provide AGM, AGC and MAC with the same reinsurance credit as reinsurers rated AA-. AGM, AGC and MAC are obligated to pay the reinsurers their share of recoveries relating to losses during the coverage period in the covered portfolio. AGC, AGM and MAC have paid approximately $19 million of premiums during 2014 for the term January 1, 2014 through December 31, 2014 and deposited approximately $19 million of securities into trust accounts for the benefit of the reinsurers to be used to pay the premium for January 1, 2015 through December 31, 2015.

Related_Party_Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions
	The Company was party to transactions with entities that are affiliated with Wilbur L. Ross, Jr., who had been a director of the Company until November 21, 2014. Mr. Ross and the funds under his control owned approximately 8.2% of the AGL common shares as of December 31, 2013 and 10.2% as of December 31, 2012. However, in 2014, Mr. Ross and the funds sold all of the AGL shares they owned and Mr. Ross resigned from the AGL board. At the time of his resignation, WL Ross and Co. LLC issued a press release announcing that Mr. Ross had been elected Vice Chairman of Bank of Cyprus and, due to rules limiting directorships of bank officers, would be resigning from the boards of directors of several companies, including that of Assured Guaranty.
	In addition, the Company retains Wellington Management Company, LLP, as investment manager for a portion of the Company's investment portfolio. Wellington Company LLP owned approximately 9.3% of the common shares of AGL as of December 31, 2014, 6.6% as of December 31, 2013 and 8.6% as of December 31, 2012.
	The net expenses from transactions with these related parties were approximately $1.9 million in 2014, with no individual related party expense item exceeding $1.9 million, $2.5 million in 2013, with no individual related party expense item exceeding $1.9 million, and $3.4 million in 2012, with no individual related party expense item exceeding $2.0 million. As of December 31, 2014, 2013 and 2012 there were no significant amounts payable to or amounts receivable from related parties. In addition, please refer to Note 19, Shareholders' Equity, for a description of the transaction under which the Company purchased common shares from funds associated with WL Ross & Co. LLC and its affiliates and from Mr. Ross.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	Leases
	AGL and its subsidiaries are party to various lease agreements accounted for as operating leases. The Company leases and occupies space in New York City through April 2026. In addition, AGL and its subsidiaries lease additional office space in various locations under non-cancelable operating leases which expire at various dates through 2021. Rent expense was $10.1 million in 2014, $9.9 million in 2013 and $10.0 million in 2012.
	Future Minimum Rental Payments
	Year		(in millions)
	2015		$	8
	2016		8
	2017		8
	2018		8
	2019		8
	Thereafter		52
	Total		$	92
	Legal Proceedings
	Lawsuits arise in the ordinary course of the Company’s business. It is the opinion of the Company’s management, based upon the information available, that the expected outcome of litigation against the Company, individually or in the aggregate, will not have a material adverse effect on the Company’s financial position or liquidity, although an adverse resolution of litigation against the Company in a fiscal quarter or year could have a material adverse effect on the Company’s results of operations in a particular quarter or year.
	Accounting Policy
	The Company establishes accruals for litigation and regulatory matters to the extent it is probable that a loss has been incurred and the amount of that loss can be reasonably estimated. For litigation and regulatory matters where a loss may be reasonably possible, but not probable, or is probable but not reasonably estimable, no accrual is established, but if the matter is material, it is disclosed, including matters discussed below. The Company reviews relevant information with respect to its litigation and regulatory matters on a quarterly, and annual basis and updates its accruals, disclosures and estimates of reasonably possible loss based on such reviews.
	In addition, in the ordinary course of their respective businesses, certain of the Company's subsidiaries assert claims in legal proceedings against third parties to recover losses paid in prior periods. For example, as described in the "Recovery Litigation," section of Note 6, Expected Loss to be Paid, in December 2008, the Company filed a claim in the Supreme Court of the State of New York against an investment manager in a transaction it insured alleging breach of fiduciary duty, gross negligence and breach of contract; discovery on the matter is ongoing. In the past, AGC and AGM have filed complaints against certain sponsors and underwriters of RMBS securities that AGC or AGM had insured, alleging that such persons had breached representations and warranties in the transaction documents, failed to cure or repurchase defective loans and/or violated state securities laws. The amounts, if any, the Company will recover in proceedings to recover losses are uncertain, and recoveries, or failure to obtain recoveries, in any one or more of these proceedings during any quarter or year could be material to the Company’s results of operations in that particular quarter or year.
	Litigation
	Proceedings Relating to the Company’s Financial Guaranty Business
	The Company receives subpoenas duces tecum and interrogatories from regulators from time to time.
	On November 28, 2011, Lehman Brothers International (Europe) (in administration) (“LBIE”) sued AGFP, an affiliate of AGC which in the past had provided credit protection to counterparties under credit default swaps. AGC acts as the credit support provider of AGFP under these credit default swaps. LBIE’s complaint, which was filed in the Supreme Court of the State of New York, alleged that AGFP improperly terminated nine credit derivative transactions between LBIE and AGFP and improperly calculated the termination payment in connection with the termination of 28 other credit derivative transactions between LBIE and AGFP. AGFP calculated that LBIE owes AGFP approximately $30 million in connection with the termination of the credit derivative transactions, whereas LBIE asserted in the complaint that AGFP owes LBIE a termination payment of approximately $1.4 billion. LBIE is seeking unspecified damages. On February 3, 2012, AGFP filed a motion to dismiss certain of the counts in the complaint, and on March 15, 2013, the court granted AGFP's motion to dismiss the count relating to improper termination of the nine credit derivative transactions and denied AGFP's motion to dismiss the count relating to the remaining transactions. Discovery has been ongoing and motions for summary judgment are due in September 2015. The Company cannot reasonably estimate the possible loss, if any, that may arise from this lawsuit.
	On September 25, 2013, Wells Fargo Bank, N.A., as trust administrator of the MASTR Adjustable Rate Mortgages Trust 2007-3, filed an interpleader complaint in the U.S. District Court for the Southern District of New York against AGM, among others, relating to the right of AGM to be reimbursed from certain cashflows for principal claims paid in respect of insured certificates. The Company estimates that an adverse outcome to the interpleader proceeding could increase losses on the transaction by approximately $10 - $20 million, net of expected settlement payments and reinsurance in force.
	Proceedings Resolved Since September 30, 2014
	Beginning in July 2008, AGM and various other financial guarantors were named in complaints filed in the Superior Court for the State of California, City and County of San Francisco by a number of plaintiffs. Subsequently, plaintiffs' counsel filed amended complaints against AGM and AGC and added additional plaintiffs. These complaints alleged that the financial guaranty insurer defendants (i) participated in a conspiracy in violation of California's antitrust laws to maintain a dual credit rating scale that misstated the credit default risk of municipal bond issuers and created market demand for municipal bond insurance, (ii) participated in risky financial transactions in other lines of business that damaged each insurer's financial condition (thereby undermining the value of each of their guaranties), and (iii) failed to adequately disclose the impact of those transactions on their financial condition. In addition to their antitrust claims, various plaintiffs asserted claims for breach of the covenant of good faith and fair dealing, fraud, unjust enrichment, negligence, and negligent misrepresentation. On October 29, 2014, AGC and AGM filed a good faith settlement notice with the Superior Court for the State of California, City and County of San Francisco, informing the court and co-defendants that AGC, AGM and the plaintiffs had reached an agreement to settle and resolve the cases as between them. The plaintiffs agreed to dismiss the litigation in exchange for AGC and AGM waiving legal fees that had been awarded to them and making a payment to such plaintiffs. On December 12, 2014, the court entered an order determining that the parties had settled in good faith. Plaintiffs have submitted all appropriate dismissals to all courts, and AGC and AGM have submitted a dismissal for their cross-appeal.
	On November 19, 2012, Lehman Brothers Holdings Inc. (“LBHI”) and Lehman Brothers Special Financing Inc. (“LBSF") commenced an adversary complaint and claim objection in the United States Bankruptcy Court for the Southern District of New York against Credit Protection Trust 283 (“CPT 283”), FSA Administrative Services, LLC, as trustee for CPT 283, and AGM, in connection with CPT 283's termination of a CDS between LBSF and CPT 283. CPT 283 terminated the CDS as a consequence of LBSF failing to make a scheduled payment owed to CPT 283, which termination occurred after LBHI filed for bankruptcy but before LBSF filed for bankruptcy. The CDS provided that CPT 283 was entitled to receive from LBSF a termination payment in that circumstance of approximately $43.8 million (representing the economic equivalent of the future fixed payments CPT 283 would have been entitled to receive from LBSF had the CDS not been terminated), and CPT 283 filed proofs of claim against LBSF and LBHI (as LBSF's credit support provider) for such amount. LBHI and LBSF sought to disallow and expunge (as impermissible and unenforceable penalties) CPT 283's proofs of claim against LBHI and LBSF and recover approximately $67.3 million, which LBHI and LBSF allege was the mark-to-market value of the CDS to LBSF (less unpaid amounts) on the day CPT 283 terminated the CDS, plus interest, attorney's fees, costs and other expenses. On the same day, LBHI and LBSF also commenced an adversary complaint and claim objection against Credit Protection Trust 207 (“CPT 207”), FSA Administrative Services, LLC, as trustee for CPT 207, and AGM, in connection with CPT 207's termination of a CDS between LBSF and CPT 207. Similarly, the CDS provided that CPT 207 was entitled to receive from LBSF a termination payment in that circumstance of $492,555. LBHI and LBSF seek to disallow and expunge CPT 207's proofs of claim against LBHI and LBSF and recover approximately $1.5 million. On January 30, 2015, the parties signed an agreement pursuant to which LBHI and LBSF dismissed their litigation related to CPT 283's and CPT 207's CDS terminations and the parties agreed that CPT 283 and CPT 207 have a total allowed claim in bankruptcy against LBSF and LBHI of $20 million.
	Proceedings Related to AGMH’s Former Financial Products Business
	The following is a description of legal proceedings involving AGMH’s former Financial Products Business. Although the Company did not acquire AGMH’s former Financial Products Business, which included AGMH’s former GIC business, medium term notes business and portions of the leveraged lease businesses, certain legal proceedings relating to those businesses are against entities that the Company did acquire. While Dexia SA and Dexia Crédit Local S.A., jointly and severally, have agreed to indemnify the Company against liability arising out of the proceedings described below, such indemnification might not be sufficient to fully hold the Company harmless against any injunctive relief or civil or criminal sanction that is imposed against AGMH or its subsidiaries.
	Governmental Investigations into Former Financial Products Business
	AGMH and/or AGM have received subpoenas duces tecum and interrogatories or civil investigative demands from the Attorneys General of the States of Connecticut, Florida, Illinois, Massachusetts, Missouri, New York, Texas and West Virginia relating to their investigations of alleged bid rigging of municipal GICs. AGMH has been responding to such requests. AGMH may receive additional inquiries from these or other regulators and expects to provide additional information to such regulators regarding their inquiries in the future. In addition,
	•	AGMH received a subpoena from the Antitrust Division of the Department of Justice in November 2006 issued in connection with an ongoing criminal investigation of bid rigging of awards of municipal GICs and other municipal derivatives; and
	•	AGM received a subpoena from the SEC in November 2006 related to an ongoing industry-wide investigation concerning the bidding of municipal GICs and other municipal derivatives.
	Pursuant to the subpoenas, AGMH has furnished to the Department of Justice and SEC records and other information with respect to AGMH’s municipal GIC business. The ultimate loss that may arise from these investigations remains uncertain.
	In July 2010, a former employee of AGM who had been involved in AGMH's former Financial Products Business was indicted along with two other persons with whom he had worked at Financial Guaranty Insurance Company. Such former employee and the other two persons were convicted on fraud conspiracy counts.  After appeal, their convictions were reversed by a three-judge panel of the U.S. Court of Appeals for the Second Circuit in November 2013. In January 2014, the Department of Justice petitioned the U.S. Court of Appeals for the Second Circuit for a panel rehearing and a rehearing en banc of the appeal; the motion was denied on August 15, 2014, and the time period within which to petition for a writ of certiorari to the Supreme Court has expired.
	Lawsuits Relating to Former Financial Products Business
	During 2008, nine putative class action lawsuits were filed in federal court alleging federal antitrust violations in the municipal derivatives industry, seeking damages and alleging, among other things, a conspiracy to fix the pricing of, and manipulate bids for, municipal derivatives, including GICs. These cases have been coordinated and consolidated for pretrial proceedings in the U.S. District Court for the Southern District of New York as MDL 1950, In re Municipal Derivatives Antitrust Litigation, Case No. 1:08-cv-2516 (“MDL 1950”). Five of these cases named both AGMH and AGM: (a) Hinds County, Mississippi v. Wachovia Bank, N.A.; (b) Fairfax County, Virginia v. Wachovia Bank, N.A.; (c) Central Bucks School District, Pennsylvania v. Wachovia Bank, N.A.; (d) Mayor and City Council of Baltimore, Maryland v. Wachovia Bank, N.A.; and (e) Washington County, Tennessee v. Wachovia Bank, N.A. In April 2009, the MDL 1950 court granted the defendants’ motion to dismiss on the federal claims, but granted leave for the plaintiffs to file an amended complaint. The Corrected Third Consolidated Amended Class Action Complaint, filed on October 9, 2013, lists neither AGM nor AGMH as a named defendant or a co-conspirator. The complaint generally seeks unspecified monetary damages, interest, attorneys’ fees and other costs. The other four cases named AGMH (but not AGM) and also alleged that the defendants violated California state antitrust law and common law by engaging in illegal bid-rigging and market allocation, thereby depriving the cities or municipalities of competition in the awarding of GICs and ultimately resulting in the cities paying higher fees for these products: (f) City of Oakland, California v. AIG Financial Products Corp.; (g) County of Alameda, California v. AIG Financial Products Corp.; (h) City of Fresno, California v. AIG Financial Products Corp.; and (i) Fresno County Financing Authority v. AIG Financial Products Corp. When the four plaintiffs filed a consolidated complaint in September 2009, the plaintiffs did not name AGMH as a defendant. However, the complaint does describe some of AGMH’s and AGM’s activities. The consolidated complaint generally seeks unspecified monetary damages, interest, attorneys’ fees and other costs. In April 2010, the MDL 1950 court granted in part and denied in part the named defendants’ motions to dismiss this consolidated complaint. The Company cannot reasonably estimate the possible loss, if any, or range of loss that may arise from these lawsuits.
	In 2008, AGMH and AGM also were named in five non-class action lawsuits originally filed in the California Superior Courts alleging violations of California law related to the municipal derivatives industry: (a) City of Los Angeles, California v. Bank of America, N.A.; (b) City of Stockton, California v. Bank of America, N.A.; (c) County of San Diego, California v. Bank of America, N.A.; (d) County of San Mateo, California v. Bank of America, N.A.; and (e) County of Contra Costa, California v. Bank of America, N.A. Amended complaints in these actions were filed in September 2009, adding a federal antitrust claim and naming AGM (but not AGMH) and AGUS, among other defendants. These cases have been transferred to the Southern District of New York and consolidated with MDL 1950 for pretrial proceedings. In late 2009, AGM and AGUS, among other defendants, were named in six additional non-class action cases filed in federal court, which also have been coordinated and consolidated for pretrial proceedings with MDL 1950: (f) City of Riverside, California v. Bank of America, N.A.; (g) Sacramento Municipal Utility District v. Bank of America, N.A.; (h) Los Angeles World Airports v. Bank of America, N.A.; (i) Redevelopment Agency of the City of Stockton v. Bank of America, N.A.; (j) Sacramento Suburban Water District v. Bank of America, N.A.; and (k) County of Tulare, California v. Bank of America, N.A. The MDL 1950 court denied AGM and AGUS’s motions to dismiss these eleven complaints in April 2010. Amended complaints were filed in May 2010. On October 29, 2010, AGM and AGUS were voluntarily dismissed with prejudice from the Sacramento Municipal Utility District case only. The complaints in these lawsuits generally seek or sought unspecified monetary damages, interest, attorneys’ fees, costs and other expenses. The Company cannot reasonably estimate the possible loss, if any, or range of loss that may arise from the remaining lawsuits.
	In May 2010, AGM and AGUS, among other defendants, were named in five additional non-class action cases filed in federal court in California: (a) City of Richmond, California v. Bank of America, N.A. (filed on May 18, 2010, N.D. California); (b) City of Redwood City, California v. Bank of America, N.A. (filed on May 18, 2010, N.D. California); (c) Redevelopment Agency of the City and County of San Francisco, California v. Bank of America, N.A. (filed on May 21, 2010, N.D. California); (d) East Bay Municipal Utility District, California v. Bank of America, N.A. (filed on May 18, 2010, N.D. California); and (e) City of San Jose and the San Jose Redevelopment Agency, California v. Bank of America, N.A (filed on May 18, 2010, N.D. California). These cases have also been transferred to the Southern District of New York and consolidated with MDL 1950 for pretrial proceedings. In September 2010, AGM and AGUS, among other defendants, were named in a sixth additional non-class action filed in federal court in New York, but which alleges violation of New York’s Donnelly Act in addition to federal antitrust law: Active Retirement Community, Inc. d/b/a Jefferson’s Ferry v. Bank of America, N.A. (filed on September 21, 2010, E.D. New York), which has also been transferred to the Southern District of New York and consolidated with MDL 1950 for pretrial proceedings. In December 2010, AGM and AGUS, among other defendants, were named in a seventh additional non-class action filed in federal court in the Central District of California, Los Angeles Unified School District v. Bank of America, N.A., and in an eighth additional non-class action filed in federal court in the Southern District of New York, Kendal on Hudson, Inc. v. Bank of America, N.A. These cases also have been consolidated with MDL 1950 for pretrial proceedings. The complaints in these lawsuits generally seek unspecified monetary damages, interest, attorneys’ fees, costs and other expenses. The Company cannot reasonably estimate the possible loss, if any, or range of loss that may arise from these lawsuits.
	In January 2011, AGM and AGUS, among other defendants, were named in an additional non-class action case filed in federal court in New York, which alleges violation of New York’s Donnelly Act in addition to federal antitrust law: Peconic Landing at Southold, Inc. v. Bank of America, N.A. This case has been consolidated with MDL 1950 for pretrial proceedings. The complaint in this lawsuit generally seeks unspecified monetary damages, interest, attorneys’ fees, costs and other expenses. The Company cannot reasonably estimate the possible loss, if any, or range of loss that may arise from this lawsuit.
	In September 2009, the Attorney General of the State of West Virginia filed a lawsuit (Circuit Ct. Mason County, W. Va.) against Bank of America, N.A. alleging West Virginia state antitrust violations in the municipal derivatives industry, seeking damages and alleging, among other things, a conspiracy to fix the pricing of, and manipulate bids for, municipal derivatives, including GICs. An amended complaint in this action was filed in June 2010, adding a federal antitrust claim and naming AGM (but not AGMH) and AGUS, among other defendants. This case has been removed to federal court as well as transferred to the S.D.N.Y. and consolidated with MDL 1950 for pretrial proceedings. AGM and AGUS answered West Virginia's Second Amended Complaint on November 11, 2013. The complaint in this lawsuit generally seeks civil penalties, unspecified monetary damages, interest, attorneys’ fees, costs and other expenses. The Company cannot reasonably estimate the possible loss, if any, or range of loss that may arise from this lawsuit.

LongTerm_Debt_and_Credit_Facil

Long-Term Debt and Credit Facilities	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Long-Term Debt and Credit Facilities
		Long-Term Debt and Credit Facilities
	The Company has outstanding long-term debt issued by AGUS and AGMH. AGUS has issued 7.0% Senior Notes, 5.0% Senior Notes and Series A, Enhanced Junior Subordinated Debentures. AGMH has issued 6 7/8% Quarterly Income Bonds Securities (“QUIBS”), 6.25% Notes and 5.60% Notes, as well $300 million Junior Subordinated Debentures. All of such debt is fully and unconditionally guaranteed by AGL; AGL's guarantee of the junior subordinated debentures is on a junior subordinated basis.
	In addition, refinancing vehicles consolidated by AGM issued notes payable to the Financial Products Companies now owned by Dexia; the refinancing vehicles borrowed the funds in order to purchase assets underlying obligations insured by AGM. See Note 11, Investments and Cash.
	Accounting Policy
	Long-term debt is recorded at principal amounts net of any unamortized original issue discount or premium and unamortized fair value adjustment for AGMH debt (as of the date of the AGMH acquisition). Discount is accreted into interest expense over the life of the applicable debt.
	Debt Issued by AGUS
	7.0% Senior Notes.  On May 18, 2004, AGUS issued $200 million of 7.0% senior notes due 2034 (“7.0% Senior Notes”) for net proceeds of $197 million. Although the coupon on the Senior Notes is 7.0%, the effective rate is approximately 6.4%, taking into account the effect of a cash flow hedge executed by the Company in March 2004.
	5.0% Senior Notes. On June 20, 2014, AGUS issued $500 million of 5.0% Senior Notes due 2024 ("5.0% Senior Notes") for net proceeds of $495 million. The notes are guaranteed by AGL. The net proceeds from the sale of the notes are being used for general corporate purposes, including the purchase of AGL common shares.
	8.5% Senior Notes.  On June 24, 2009, AGL issued 3,450,000 equity units for net proceeds of approximately $167 million in a registered public offering. The net proceeds of the offering were used to pay a portion of the consideration for the acquisition of AGMH. Each equity unit consisted of (i) a 5.0% undivided beneficial ownership interest in $1,000 principal amount of 8.5% senior notes due 2014 issued by AGUS and (ii) a forward purchase contract obligating the holders to purchase $50 of AGL common shares in June 2012. On June 1, 2012, the Company completed the remarketing of the $173 million aggregate principal amount of 8.5% Senior Notes; AGUS purchased all of the Senior Notes in the remarketing at a price of 100% of the principal amount thereof, and retired all of such notes on June 1, 2012. The proceeds from the remarketing were used to satisfy the obligations of the holders of the Equity Units to purchase AGL common shares pursuant to the forward purchase contract. Accordingly, on June 1, 2012, AGL issued 3.8924 common shares to holders of each Equity Unit, which represented a settlement rate of 3.8685 common shares plus certain anti-dilution adjustments, or an aggregate of 13,428,770 common shares at approximately $12.85 per share. The Equity Units ceased to exist when the forward purchase contracts were settled on June 1, 2012.
	Series A Enhanced Junior Subordinated Debentures.  On December 20, 2006, AGUS issued $150 million of the Debentures due 2066. The Debentures pay a fixed 6.40% rate of interest until December 15, 2016, and thereafter pay a floating rate of interest, reset quarterly, at a rate equal to three month LIBOR plus a margin equal to 2.38%. AGUS may select at one or more times to defer payment of interest for one or more consecutive periods for up to ten years. Any unpaid interest bears interest at the then applicable rate. AGUS may not defer interest past the maturity date.
	Debt Issued by AGMH
	6 7/8% QUIBS.  On December 19, 2001, AGMH issued $100 million face amount of 6 7/8% QUIBS due December 15, 2101, which are callable without premium or penalty.
	6.25% Notes.  On November 26, 2002, AGMH issued $230 million face amount of 6.25% Notes due November 1, 2102, which are callable without premium or penalty in whole or in part.
	5.60% Notes.  On July 31, 2003, AGMH issued $100 million face amount of 5.60% Notes due July 15, 2103, which are callable without premium or penalty in whole or in part.
	Junior Subordinated Debentures.  On November 22, 2006, AGMH issued $300 million face amount of Junior Subordinated Debentures with a scheduled maturity date of December 15, 2036 and a final repayment date of December 15, 2066. The final repayment date of December 15, 2066 may be automatically extended up to four times in five-year increments provided certain conditions are met. The debentures are redeemable, in whole or in part, at any time prior to December 15, 2036 at their principal amount plus accrued and unpaid interest to the date of redemption or, if greater, the make-whole redemption price. Interest on the debentures will accrue from November 22, 2006 to December 15, 2036 at the annual rate of 6.40%. If any amount of the debentures remains outstanding after December 15, 2036, then the principal amount of the outstanding debentures will bear interest at a floating interest rate equal to one-month LIBOR plus 2.215% until repaid. AGMH may elect at one or more times to defer payment of interest on the debentures for one or more consecutive interest periods that do not exceed ten years. In connection with the completion of this offering, AGMH entered into a replacement capital covenant for the benefit of persons that buy, hold or sell a specified series of AGMH long-term indebtedness ranking senior to the debentures. Under the covenant, the debentures will not be repaid, redeemed, repurchased or defeased by AGMH or any of its subsidiaries on or before the date that is 20 years prior to the final repayment date, except to the extent that AGMH has received proceeds from the sale of replacement capital securities. The proceeds from this offering were used to pay a dividend to the shareholders of AGMH.
	Debt Issued by AGM
	In order to mitigate certain financial guaranty insurance losses, special purpose entities that AGM consolidates ("refinancing vehicles") borrowed funds from the former AGMH subsidiaries that conducted AGMH’s Financial Products Business (the “Financial Products Companies”). The Company refers to such debt as the "Notes Payable." The Financial Products Companies issued GICs that AGM insured, and loaned the proceeds to the refinancing vehicles. The refinancing vehicles used the proceeds from the Notes Payable to purchase certain obligations insured by AGM or collateral underlying such obligations and reimbursed AGM for its claim payments, in exchange for AGM assigning to the refinancing vehicles certain of its rights against the trusts in the applicable transactions.
	The principal and carrying values of the Company’s long-term debt are presented in the table below.
	Principal and Carrying Amounts of Debt
		As of December 31, 2014						As of December 31, 2013
		Principal			Carrying			Principal			Carrying
					Value						Value
		(in millions)
	AGUS:
	7.0% Senior Notes	$	200		$	198		$	200		$	198
	5.0% Senior Notes	500			499			—			—
	Series A Enhanced Junior Subordinated Debentures	150			150			150			150
	Total AGUS	850			847			350			348
	AGMH:
	67/8% QUIBS	100			68			100			68
	6.25% Notes	230			139			230			138
	5.60% Notes	100			55			100			55
	Junior Subordinated Debentures	300			175			300			169
	Total AGMH	730			437			730			430
	AGM:
	Notes Payable	16			19			34			38
	Total AGM	16			19			34			38
	Total	$	1,596		$	1,303		$	1,114		$	816
	Principal payments due under the long-term debt are as follows:
	Expected Maturity Schedule of Debt
	Expected Withdrawal Date		AGUS			AGMH			AGM			Total
			(in millions)
	2015		$	—		$	—		$	7		$	7
	2016		—			—			3			3
	2017		—			—			3			3
	2018		—			—			2			2
	2019		—			—			1			1
	2020-2039		700			—			—			700
	2040-2059		—			—			—			—
	2060-2079		150			300			—			450
	Thereafter		—			430			—			430
	Total		$	850		$	730		$	16		$	1,596
	Interest Expense
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	AGUS:
	7.0% Senior Notes	$	13		$	13		$	13
	5.0% Senior Notes	13			—			—
	8.50% Senior Notes	—			—			8
	Series A Enhanced Junior Subordinated Debentures	10			10			10
	Total AGUS	36			23			31
	AGMH:
67/8% QUIBS	7			7			7
6.25% Notes	16			16			16
5.60% Notes	6			6			6
Junior Subordinated Debentures	25			25			25
Total AGMH	54			54			54
AGM:
Notes Payable	2			5			7
Total AGM	2			5			7
Total	$	92		$	82		$	92
Recourse Credit Facilities
2009 Strip Coverage Facility
In connection with the Company's acquisition of AGMH and its subsidiaries from Dexia Holdings Inc., AGM agreed to retain the risks relating to the debt and strip policy portions of the leveraged lease business. The liquidity risk to AGM related to the strip policy portion of the leveraged lease business is mitigated by the strip coverage facility described below.
In a leveraged lease transaction, a tax-exempt entity (such as a transit agency) transfers tax benefits to a tax-paying entity by transferring ownership of a depreciable asset, such as subway cars. The tax-exempt entity then leases the asset back from its new owner.
If the lease is terminated early, the tax-exempt entity must make an early termination payment to the lessor. A portion of this early termination payment is funded from monies that were pre-funded and invested at the closing of the leveraged lease transaction (along with earnings on those invested funds). The tax-exempt entity is obligated to pay the remaining, unfunded portion of this early termination payment (known as “strip coverage”) from its own sources. AGM issued financial guaranty insurance policies (known as “strip policies”) that guaranteed the payment of these unfunded strip coverage amounts to the lessor, in the event that a tax-exempt entity defaulted on its obligation to pay this portion of its early termination payment. AGM can then seek reimbursement of its strip policy payments from the tax-exempt entity, and can also sell the transferred depreciable asset and reimburse itself from the sale proceeds.
Currently, all the leveraged lease transactions in which AGM acts as strip coverage provider are breaching a rating trigger related to AGM and are subject to early termination. However, early termination of a lease does not result in a draw on the AGM policy if the tax-exempt entity makes the required termination payment. If all the leases were to terminate early and the tax-exempt entities do not make the required early termination payments, then AGM would be exposed to possible liquidity claims on gross exposure of approximately $1.2 billion as of December 31, 2014. To date, none of the leveraged lease transactions that involve AGM has experienced an early termination due to a lease default and a claim on the AGM policy. It is difficult to determine the probability that AGM will have to pay strip provider claims or the likely aggregate amount of such claims. At December 31, 2014, approximately $1.4 billion of cumulative strip par exposure had been terminated since 2008 on a consensual basis. The consensual terminations have resulted in no claims on AGM.
On July 1, 2009, AGM and Dexia Crédit Local S.A., acting through its New York Branch (“Dexia Crédit Local (NY)”), entered into a credit facility (the “Strip Coverage Facility”). Under the Strip Coverage Facility, Dexia Crédit Local (NY) agreed to make loans to AGM to finance all draws made by lessors on AGM strip policies that were outstanding as of November 13, 2008, up to the commitment amount. The commitment amount of the Strip Coverage Facility was $1 billion at closing of the Company's acquisition of AGMH. AGM has reduced the maximum commitment amount from time to time, after taking into account its experience with its exposure to leveraged lease transactions. Most recently, as of June 30, 2014, AGM reduced the maximum commitment amount to $495 million and agreed with Dexia Crédit Local (NY) that the commitment amount would no longer amortize on a scheduled monthly basis.
Fundings under this facility are subject to certain conditions precedent, and their repayment is collateralized by a security interest that AGM granted to Dexia Crédit Local (NY) in amounts that AGM recovers—from the tax-exempt entity, or from asset sale proceeds—following its payment of strip policy claims. On June 30, 2014, AGM and Dexia Crédit Local (NY) agreed to shorten the duration of the facility. Accordingly, the Strip Coverage Facility will terminate upon the earliest to occur of an AGM change of control, the reduction of the commitment amount to $0 in accordance with the terms of the facility, and June 30, 2024 (rather than the original maturity date of January 31, 2042).
The Strip Coverage Facility’s financial covenants require that AGM and its subsidiaries maintain:
•	a maximum debt-to-capital ratio of 30%; and
•	a minimum net worth of 75% of consolidated net worth as of July 1, 2009, plus, beginning June 30, 2015 and on each anniversary of such date, an amount equal to the product of (i) 25% of the aggregate consolidated net income (or loss) for the period beginning July 2, 2009 and ending on June 30, 2014 and (ii) a fraction, the numerator of which is the commitment amount as of the relevant calculation date and the denominator of which is $1 billion.
The Company was in compliance with all financial covenants as of December 31, 2014.
The Strip Coverage Facility contains restrictions on AGM, including, among other things, in respect of its ability to incur debt, permit liens, pay dividends or make distributions, dissolve or become party to a merger or consolidation. Most of these restrictions are subject to exceptions. The Strip Coverage Facility has customary events of default, including (subject to certain materiality thresholds and grace periods) payment default, bankruptcy or insolvency proceedings and cross-default to other debt agreements.
As of December 31, 2014, no amounts were outstanding under this facility, nor have there been any borrowings during the life of this facility.
Intercompany Credit Facility
On October 25, 2013, AGL, as borrower, and AGUS, as lender, entered into a revolving credit facility pursuant to which AGL may, from time to time, borrow for general corporate purposes. Under the credit facility, AGUS committed to lend a principal amount not exceeding $225 million in the aggregate. Such commitment terminates on the October 25, 2018 (the “loan termination date”). The unpaid principal amount of each loan will bear interest at a fixed rate equal to 100% of the then applicable Federal short-term or mid-term interest rate, as the case may be, as determined under Internal Revenue Code Sec. 1274(d), and interest on all loans will be computed for the actual number of days elapsed on the basis of a year consisting of 360 days. Accrued interest on all loans will be paid on the last day of each June and December, beginning on December 31, 2013, and at maturity.  AGL must repay the then unpaid principal amounts of the loans by the third anniversary of the loan termination date. No amounts are currently outstanding under the credit facility.
Committed Capital Securities
On April 8, 2005, AGC entered into separate agreements (the “Put Agreements”) with four custodial trusts (each, a “Custodial Trust”) pursuant to which AGC may, at its option, cause each of the Custodial Trusts to purchase up to $50 million of perpetual preferred stock of AGC (the “AGC Preferred Stock”). The custodial trusts were created as a vehicle for providing capital support to AGC by allowing AGC to obtain immediate access to new capital at its sole discretion at any time through the exercise of the put option. If the put options were exercised, AGC would receive $200 million in return for the issuance of its own perpetual preferred stock, the proceeds of which may be used for any purpose, including the payment of claims. The put options have not been exercised through the date of this filing.
Distributions on the AGC CCS are determined pursuant to an auction process. On April 7, 2008 this auction process failed, thereby increasing the annualized rate on the AGC CCS to one-month LIBOR plus 250 basis points. Distributions on the AGC preferred stock will be determined pursuant to the same process.
In June 2003, $200 million of “AGM CPS”, money market preferred trust securities, were issued by trusts created for the primary purpose of issuing the AGM CPS, investing the proceeds in high-quality commercial paper and selling put options to AGM, allowing AGM to issue the trusts non-cumulative redeemable perpetual preferred stock (the “AGM Preferred Stock”) of AGM in exchange for cash. There are four trusts, each with an initial aggregate face amount of $50 million. These trusts hold auctions every 28 days, at which time investors submit bid orders to purchase AGM CPS. If AGM were to exercise a put option, the applicable trust would transfer the portion of the proceeds attributable to principal received upon maturity of its assets, net of expenses, to AGM in exchange for AGM Preferred Stock. AGM pays a floating put premium to the trusts, which represents the difference between the commercial paper yield and the winning auction rate (plus all fees and expenses of the trust). If an auction does not attract sufficient clearing bids, however, the auction rate is subject to a maximum rate of one-month LIBOR plus 200 basis points for the next succeeding distribution period. Beginning in August 2007, the AGM CPS required the maximum rate for each of the relevant trusts. AGM continues to have the ability to exercise its put option and cause the related trusts to purchase AGM Preferred Stock. The trusts provide AGM access to new capital at its sole discretion through the exercise of the put options. As of December 31, 2014 the put option had not been exercised. The Company does not consider itself to be the primary beneficiary of the trusts. See Note 8, Fair Value Measurement, –Other Assets–Committed Capital Securities, for a fair value measurement discussion.

Earnings_Per_Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share
	Accounting Policy
	The Company computes earnings per share ("EPS") using a two-class method by including participating securities which entitle their holders to receive nonforfeitable dividends or dividend equivalents before vesting. Restricted stock awards and share units under the AGC supplemental employee retirement plan ("SERP") plan are considered participating securities as they received non-forfeitable rights to dividends at the same rate as common stock.
	The two-class method of computing EPS is an earnings allocation formula that determines EPS for each class of common stock and participating security according to dividends declared (or accumulated) and participation rights in undistributed earnings. Basic EPS is then calculated by dividing net (loss) income available to common shareholders of Assured Guaranty by the weighted‑average number of common shares outstanding during the period. Diluted EPS adjusts basic EPS for the effects of restricted stock, stock options, equity units and other potentially dilutive financial instruments (“dilutive securities”), only in the periods in which such effect is dilutive. The effect of the dilutive securities is reflected in diluted EPS by application of the more dilutive of (1) the treasury stock method or (2) the two-class method assuming nonvested shares are not converted into common shares. With respect to the equity units, which were settled on June 1, 2012 (see Note 17, Long-Term Debt and Credit Facilities), the Company used the treasury stock method in computing diluted EPS. Equity forwards were included in the calculation of basic EPS when such forward contracts were satisfied and the holders thereof became common stock holders. The Company has a single class of common stock.
	Computation of Earnings Per Share
		Year Ended December 31,
		2014		2013		2012
		(in millions, except per share amounts)
	Basic EPS:
	Net income (loss) attributable to AGL	$	1,088	$	808	110
	Less: Distributed and undistributed income (loss) available to nonvested shareholders	0		1		0
	Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	1,088	$	807	110
	Basic shares	172.6		186.6		189.2
	Basic EPS	$	6.3	$	4.32	$	0.58
	Diluted EPS:
	Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	1,088	$	807	$	110
	Plus: Re-allocation of undistributed income (loss) available to nonvested shareholders of AGL and subsidiaries	0		0		0
	Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, diluted	$	1,088	$	807	$	110
	Basic shares	172.6		186.6		189.2
	Effect of dilutive securities:
	Options and restricted stock awards	1		1		0.8
	Equity units	—		—		0.7
	Diluted shares	173.6		187.6		190.7
	Diluted EPS	$	6.26	$	4.3	$	0.57
	Potentially dilutive securities excluded from computation of EPS because of antidilutive effect	1.6		2.7		9.9

Shareholders_Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Shareholders' Equity	Shareholders' Equity
	Share Issuances
	AGL has authorized share capital of $5 million divided into 500,000,000 shares, par value $0.01 per share. Except as described below, AGL's common shares have no preemptive rights or other rights to subscribe for additional common shares, no rights of redemption, conversion or exchange and no sinking fund rights. In the event of liquidation, dissolution or winding-up, the holders of AGL's common shares are entitled to share equally, in proportion to the number of common shares held by such holder, in AGL's assets, if any remain after the payment of all its liabilities and the liquidation preference of any outstanding preferred shares. Under certain circumstances, AGL has the right to purchase all or a portion of the shares held by a shareholder at fair market value. All of the common shares are fully paid and non assessable. Holders of AGL's common shares are entitled to receive dividends as lawfully may be declared from time to time by AGL's Board of Directors.
	In general, and except as provided below, shareholders have one vote for each common share held by them and are entitled to vote with respect to their fully paid shares at all meetings of shareholders. However, if, and so long as, the common shares (and other of AGL's shares) of a shareholder are treated as "controlled shares" (as determined pursuant to section 958 of the Code) of any U.S. Person and such controlled shares constitute 9.5% or more of the votes conferred by AGL's issued and outstanding shares, the voting rights with respect to the controlled shares owned by such U.S. Person shall be limited, in the aggregate, to a voting power of less than 9.5% of the voting power of all issued and outstanding shares, under a formula specified in AGL's Bye-laws. The formula is applied repeatedly until there is no U.S. Person whose controlled shares constitute 9.5% or more of the voting power of all issued and outstanding shares and who generally would be required to recognize income with respect to AGL under the Code if AGL were a controlled foreign corporation as defined in the Code and if the ownership threshold under the Code were 9.5% (as defined in AGL's Bye-Laws as a "9.5% U.S. Shareholder").
	Subject to AGL's Bye-Laws and Bermuda law, AGL's Board of Directors has the power to issue any of AGL's unissued shares as it determines, including the issuance of any shares or class of shares with preferred, deferred or other special rights.
	Issuance of Shares
		Number of		Price per			Proceeds			Net
		Shares		Share						Proceeds
		(in millions, except share and per share amounts)
	June 1, 2012(1)	13,428,770		$	12.85		$	173		$	173
	____________________
	-1	Relates to the settlement of forward purchase contracts. See Note 17, Long-Term Debt and Credit Facilities.
	Under AGL's Bye-Laws and subject to Bermuda law, if AGL's Board of Directors determines that any ownership of AGL's shares may result in adverse tax, legal or regulatory consequences to the Company, any of the Company's subsidiaries or any of its shareholders or indirect holders of shares or its Affiliates (other than such as AGL's Board of Directors considers de minimis), the Company has the option, but not the obligation, to require such shareholder to sell to AGL or to a third party to whom AGL assigns the repurchase right the minimum number of common shares necessary to avoid or cure any such adverse consequences at a price determined in the discretion of the Board of Directors to represent the shares' fair market value (as defined in AGL's Bye-Laws). In addition, AGL's Board of Directors may determine that shares held carry different voting rights when it deems it appropriate to do so to (i) avoid the existence of any 9.5% U.S. Shareholder; and (ii) avoid adverse tax, legal or regulatory consequences to AGL or any of its subsidiaries or any direct or indirect holder of shares or its affiliates. "Controlled shares" includes, among other things, all shares of AGL that such U.S. Person is deemed to own directly, indirectly or constructively (within the meaning of section 958 of the Code). Further, these provisions do not apply in the event one shareholder owns greater than 75% of the voting power of all issued and outstanding shares.
	Under these provisions, certain shareholders may have their voting rights limited to less than one vote per share, while other shareholders may have voting rights in excess of one vote per share. Moreover, these provisions could have the effect of reducing the votes of certain shareholders who would not otherwise be subject to the 9.5% limitation by virtue of their direct share ownership. AGL's Bye-laws provide that it will use its best efforts to notify shareholders of their voting interests prior to any vote to be taken by them.
	Share Repurchases
	As of December 31, 2014, the Company's share repurchase authorization was $210 million. The Company expects the repurchases to be made from time to time in the open market or in privately negotiated transactions. The timing, form and amount of the share repurchases under the program are at the discretion of management and will depend on a variety of factors, including availability of funds at the holding companies, market conditions, the Company's capital position, legal requirements and other factors. The repurchase program may be modified, extended or terminated by the Board of Directors at any time. It does not have an expiration date. In 2014, the Company repurchased a total of 24.4 million common shares for approximately $590 million at an average price of $24.17 per share. The 2013 share repurchases included 5.0 million common shares purchased on June 5, 2013 from funds associated with WL Ross & Co. LLC and its affiliates (collectively, the “WLR Funds”) and Wilbur L. Ross, Jr., a director of the Company, for $109.7 million.
	Share Repurchases
	Year		Number of Shares Repurchased		Total Payments			Average Price Paid Per Share
					(in millions)
	2015 (through February 26, 2015 on a settlement date basis)		3,581,767		$	92		$	25.63
	2014		24,413,781		$	590		$	24.17
	2013		12,512,759		264			21.12
	2012		2,066,759		24			11.76
	Deferred Compensation
	Each of the Chief Executive Officer and the General Counsel of the Company has elected to invest a portion of his AGL supplemental employee retirement plan ("SERP") account in the employer stock fund within the SERP. Each unit in the employer stock fund represents the right to receive one AGL common share upon a distribution from the SERP. Each unit equals the number of AGL common shares which could have been purchased with the value of the account deemed invested in the employer stock fund as of the date of such election. The election to invest in the employer stock fund is irrevocable (i.e., any portion of a SERP account allocated to the employer stock fund and invested in units shall remain allocated to the employer stock fund until the participant receives a distribution from SERP). At the same time such investment elections were made, the Company purchased AGL common shares and placed such shares in trust to be distributed to the Chief Executive Officer and the General Counsel upon a distribution from the SERP in settlement of their units invested in the employer stock fund. As of December 31, 2014 and 2013, the Company had 320,193 and 320,193 shares, respectively, in the trust. The Company recorded the purchase of such shares in “deferred equity compensation” in the consolidated balance sheet.
	Certain executives of the Company elected to invest a portion of their AGC SERP accounts in the employer stock fund in the AGC SERP. Each unit in the employer stock fund represents the right to receive one AGL common share upon a distribution from the AGC SERP. Each unit equals the number of AGL common shares which could have been purchased with the value of the account deemed invested in the employer stock fund as of the date of such election. As of December 31, 2014 and 2013, there were 74,309 and 74,309 units, respectively, in the AGC SERP. See Note 20, Employee Benefit Plans.
	Dividends
	Any determination to pay cash dividends is at the discretion of the Company's Board of Directors, and depends upon the Company's results of operations and operating cash flows, its financial position and capital requirements, general business conditions, legal, tax, regulatory, rating agency and contractual restrictions on the payment of dividends, and any other factors the Company's Board of Directors deems relevant. For more information concerning regulatory constraints that affect the Company's ability to pay dividends, see Note 12, Insurance Company Regulatory Requirements.
	On February 4, 2015, the Company declared a quarterly dividend of $0.12 per common share, an increase of 9% from a quarterly dividend of $0.11 per common share paid in 2014. On February 5, 2014, the Company declared a quarterly dividend of $0.11 per common share, an increase of 10% from a quarterly dividend of $0.10 per common share paid in 2013. On February 7, 2013, the Company declared a quarterly dividend of $0.10 per common share, an increase of 11% from a quarterly dividend of $0.09 per common share paid in 2012.

Employee_Benefit_Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2014
Employee Benefit Plans [Abstract]
Employee Benefit Plans	Employee Benefit Plans
	Accounting Policy
	The expense for Performance Retention Plan awards is recognized straight-line over the requisite service period, with the exception of retirement eligible employees. For retirement eligible employees, the expense is recognized immediately.
	Share-based compensation expense is based on the grant date fair value using the grant date closing price, the lattice, Monte Carlo or Black-Scholes pricing models. The Company amortizes the fair value of share-based awards on a straight-line basis over the requisite service periods of the awards, which are generally the vesting periods, with the exception of retirement‑eligible employees. For retirement-eligible employees, certain awards contain retirement provisions and therefore are amortized over the period through the date the employee first becomes eligible to retire and is no longer required to provide service to earn part or all of the award.
	The fair value of each award under the Assured Guaranty Ltd. Employee Stock Purchase Plan is estimated at the beginning of each offering period using the Black-Scholes option valuation model.
	Assured Guaranty Ltd. 2004 Long-Term Incentive Plan
	Under the Assured Guaranty Ltd. 2004 Long-Term Incentive Plan, as amended (the “Incentive Plan”), the number of AGL common shares that may be delivered under the Incentive Plan may not exceed 18,670,000. In the event of certain transactions affecting AGL's common shares, the number or type of shares subject to the Incentive Plan, the number and type of shares subject to outstanding awards under the Incentive Plan, and the exercise price of awards under the Incentive Plan, may be adjusted.
	The Incentive Plan authorizes the grant of incentive stock options, non-qualified stock options, stock appreciation rights, and full value awards that are based on AGL's common shares. The grant of full value awards may be in return for a participant's previously performed services, or in return for the participant surrendering other compensation that may be due, or may be contingent on the achievement of performance or other objectives during a specified period, or may be subject to a risk of forfeiture or other restrictions that will lapse upon the achievement of one or more goals relating to completion of service by the participant, or achievement of performance or other objectives. Awards under the Incentive Plan may accelerate and become vested upon a change in control of AGL.
	The Incentive Plan is administered by a committee of the Board of Directors. The Compensation Committee of the Board serves as this committee except as otherwise determined by the Board. The Board may amend or terminate the Incentive Plan. As of December 31, 2014, 10,712,661 common shares were available for grant under the Incentive Plan.
	Time Vested Stock Options
	Nonqualified or incentive stock options may be granted to employees and directors of the Company. Stock options are generally granted once a year with exercise prices equal to the closing price on the date of grant. To date, the Company has only issued non-qualified stock options. All stock options, except for performance stock options, granted to employees vest in equal annual installments over a three-year period and expire seven years or ten years from the date of grant. Stock options granted to directors vest over one year and expire in seven years or ten years from grant date. None of the Company's options, except for performance stock options, have a performance or market condition.
	Time Vested Stock Options
		Options for			Weighted				Weighted			Number of	Year of
		Common Shares			Average				Average Grant			Exercisable	Expiration
					Exercise Price				Date Fair Value			Options
									Per Share
	Balance as of December 31, 2013	3,129,251			$	20.97						2,987,088
	Options granted	83,162			21.88				$	10.35			2021
	Options exercised	(409,560	)		17.88
	Options forfeited/expired	—			—
	Balance as of December 31, 2014	2,802,853			$	21.45						2,631,653
	As of December 31, 2014, the aggregate intrinsic value and weighted average remaining contractual term of stock options outstanding were $13 million and 2.9 years, respectively. As of December 31, 2014, the aggregate intrinsic value and weighted average remaining contractual term of exercisable stock options were $12 million and 2.7 years, respectively.
	As of December 31, 2014 the total unrecognized compensation expense related to outstanding nonvested stock options was $1 million, which will be adjusted in the future for the difference between estimated and actual forfeitures. The Company expects to recognize that expense over the weighted average remaining service period of 1.3 years.
	Lattice Option Pricing
	Weighted Average Assumptions
		2014			2013				2012
	Dividend yield	2.03	%		2.07		%		2.06	%
	Expected volatility	53.24	%		53.41		%		58.89	%
	Risk free interest rate	2.21	%		1.35		%		1.45	%
	Expected life	6.6 years			6.6 years				6.6 years
	Forfeiture rate	3.5	%		4.5		%		4.5	%
	Weighted average grant date fair value	10.35			$	8.94			8.62
	The Company uses a lattice model to value its employee and director stock options, rather than a simple Black-Scholes-Merton (“Black-Scholes”) formula. The Black-Scholes approach is designed for options exercisable only at maturity (European style), but can still be used to value options exercisable at any time after they vest (“American style”) as long as no dividend payments are being made on the stock.  A lattice model can be used for both European and American style options and regardless of whether or not the stock is paying regular dividends. Because the options the Company has granted to its employees and directors are American style and because the Company pays regular dividends on its stock, the Company has selected a lattice model as the appropriate method to value these options.
	The expected dividend yield is based on the current expected annual dividend and share price on the grant date. The expected volatility is estimated at the date of grant based on an average of the 7-year historical share price volatility and implied volatilities of certain at-the-money actively traded call options in the Company. The risk-free interest rate is the implied 7-year yield currently available on U.S. Treasury zero-coupon issues at the date of grant. The forfeiture rate is based on the historical employee termination information.
	The total intrinsic value of stock options exercised during the years ended December 31, 2014, 2013 and 2012 was $3.0 million, $7.5 million and $0.1 million, respectively. During the years ended December 31, 2014, 2013 and 2012, $4.3 million, $2.6 million and $44 thousand, respectively, was received from the exercise of stock options. In order to satisfy stock option exercises, the Company issues new shares.
	Performance Stock Options
	The Company grants performance stock options under the Incentive Plan. These awards are non-qualified stock options with exercise prices equal to the closing price an AGL common share on the applicable date of grant. These awards vest 35%, 50% or 100%, if the price of AGL's common shares using the highest 40-day average share price during the relevant performance period reaches certain hurdles. If the share price is between the specified levels, the vesting level will be interpolated accordingly. These awards expire seven years from the date of grant.
	Performance Stock Options
		Options for			Weighted				Weighted			Number of	Year of
		Common Shares			Average				Average Grant			Exercisable	Expiration
					Exercise Price				Date Fair Value			Options
									Per Share
	Balance as of December 31, 2013	365,717			$	17.8						0
	Options granted	—			—				$	—			—
	Options exercised	—			—
	Options forfeited/expired	(118,838	)		17.44
	Balance as of December 31, 2014	246,879			$	17.97						0
	In order to satisfy stock option exercises, the Company issues new shares.
	As of December 31, 2014, the aggregate intrinsic value and weighted average remaining contractual term of performance stock options outstanding were $2 million and 4.4 years, respectively. As of December 31, 2014, no performance options were exercisable.
	As of December 31, 2014 the total unrecognized compensation expense related to outstanding nonvested performance stock options was $0.3 million, which will be adjusted in the future for the difference between estimated and actual forfeitures. The Company expects to recognize that expense over the weighted average remaining service period of 0.9 years.
	Monte Carlo and Lattice Option Pricing
	Weighted Average Assumptions (1)
		2013				2012
	Dividend yield	2.07		%		2.06		%
	Expected volatility	53.5		%		58.89		%
	Risk free interest rate	1.36		%		1.45		%
	Expected life	6.3 years				6.3 years
	Forfeiture rate	4.5		%		4.5		%
	Weighted average grant date fair value	$	8.17			$	7.84
	____________________
	-1	No options were granted in 2014.
	The expected dividend yield is based on the current expected annual dividend and share price on the grant date. The expected volatility is estimated at the date of grant based on an average of the 7-year historical share price volatility and implied volatilities of certain at-the-money actively traded call options in the Company. The risk-free interest rate is the implied 7-year yield currently available on U.S. Treasury zero-coupon issues at the date of grant. The forfeiture rate is based on the historical employee termination information.
	Restricted Stock Awards
	Restricted stock awards to employees generally vest in equal annual installments over a four-year period and restricted stock awards to outside directors vest in full in one year. Restricted stock awards are amortized on a straight-line basis over the requisite service periods of the awards, and restricted stock awards to outside directors are amortized over one year, which are generally the vesting periods, with the exception of retirement‑eligible employees, discussed above.
Restricted Stock Award Activity
Nonvested Shares		Number of			Weighted
		Shares			Average Grant
					Date Fair Value
					Per Share
Nonvested at December 31, 2013		48,273			$	23.2
Granted		47,747			23.98
Vested		(48,273	)		23.2
Forfeited		(4,170	)		23.98
Nonvested at December 31, 2014		43,577			$	23.98
As of December 31, 2014 the total unrecognized compensation cost related to outstanding nonvested restricted stock awards was $0.4 million, which the Company expects to recognize over the weighted‑average remaining service period of 0.4 years. The total fair value of shares vested during the years ended December 31, 2014, 2013 and 2012 was $1 million, $1 million and $1 million, respectively.
Restricted Stock Units
Restricted stock units are valued based on the closing price of the underlying shares at the date of grant. Restricted stock units awarded to employees have vesting terms similar to those of the restricted stock awards and are delivered on the vesting date. The Company has granted restricted stock units to directors of the Company. Restricted stock units awarded to directors vest over a one-year period and are delivered after directors terminate from the board of directors.
Restricted Stock Unit Activity
(Excluding Dividend Equivalents)
Nonvested Stock Units		Number of			Weighted
		Stock Units			Average Grant
					Date Fair Value
					Per Share
Nonvested at December 31, 2013		736,409			$	17.63
Granted		238,976			21.61
Delivered		(284,082	)		17.13
Forfeited		—			—
Nonvested at December 31, 2014		691,303			$	19.23
As of December 31, 2014, the total unrecognized compensation cost related to outstanding nonvested restricted stock units was $5.2 million, which the Company expects to recognize over the weighted‑average remaining service period of 1.9 years. The total fair value of restricted stock units delivered during the years ended December 31, 2014, 2013 and 2012 was $5 million, $5 million and $6 million, respectively.
Performance Restricted Stock Units
Beginning in 2012, the Company has granted performance restricted stock units under the Incentive Plan. These awards vest 35%, 100%, or 200%, if the price of AGL's common shares using the highest 40-day average share price during the relevant performance period reaches certain hurdles. If the share price is between the specified levels, the vesting level will be interpolated accordingly.
Performance Restricted Stock Unit Activity
Performance Restricted Stock Units		Number of			Weighted
		Performance Share Units			Average Grant
					Date Fair Value
					Per Share
Nonvested at December 31, 2013		223,410			$	27.79
Granted		203,287			25.17
Delivered		—			—
Forfeited		(3,395	)		27.35
Nonvested at December 31, 2014		423,302			$	26.72
As of December 31, 2014, the total unrecognized compensation cost related to outstanding nonvested performance share units was $3.7 million, which the Company expects to recognize over the weighted‑average remaining service period of 1.9 years.
Employee Stock Purchase Plan
The Company established the AGL Employee Stock Purchase Plan ("Stock Purchase Plan") in accordance with Internal Revenue Code Section 423, and participation is available to all eligible employees. Maximum annual purchases by participants are limited to the number of whole shares that can be purchased by an amount equal to 10% of the participant's compensation or, if less, shares having a value of $25,000. Participants may purchase shares at a purchase price equal to 85% of the lesser of the fair market value of the stock on the first day or the last day of the subscription period. The Company has reserved for issuance and purchases under the Stock Purchase Plan 600,000 Assured Guaranty Ltd. common shares.
The fair value of each award under the Stock Purchase Plan is estimated at the beginning of each offering period using the Black‑Scholes option‑pricing model and the following assumptions: a) the expected dividend yield is based on the current expected annual dividend and share price on the grant date; b) the expected volatility is estimated at the date of grant based on the historical share price volatility, calculated on a daily basis; c) the risk-free rate for periods within the contractual life of the option is based on the U.S. Treasury yield curve in effect at the time of grant; and d) the expected life is based on the term of the offering period.
Stock Purchase Plan
	Year Ended December 31,
	2014				2013				2012
	(dollars in millions)
Proceeds from purchase of shares by employees	$	0.9			$	0.9			$	0.6
Number of shares issued by the Company	43,273				57,980				54,612
Recorded in share-based compensation, after the effects of DAC	$	0.2			$	0.3			$	0.2
Share‑Based Compensation Expense
The following table presents stock based compensation costs by type of award and the effect of deferring such costs as policy acquisition costs, pre-tax. Amortization of previously deferred stock compensation costs is not shown in the table below.
Share‑Based Compensation Expense Summary
	Year Ended December 31,
	2014				2013				2012
	(in millions)
Share‑Based Employee Cost:
Recurring amortization	$	9			$	7			$	6
Accelerated amortization for retirement eligible employees	0				—				1
Subtotal	9				7				7
ESPP	0				0				0
Total Share‑Based Employee Cost	9				7				7
Total Share‑Based Directors Cost	1				1				1
Total Share‑Based Cost	10				8				8
Less: Share‑based compensation capitalized as DAC	0				—				1
Share‑based compensation expense	$	10			$	8			$	7
Income tax benefit	$	2			$	2			$	2
Defined Contribution Plan
The Company maintains a savings incentive plan, which is qualified under Section 401(a) of the Internal Revenue Code for U.S. employees. The savings incentive plan is available to eligible full-time employees upon hire. Eligible participants could contribute a percentage of their salary subject to a maximum of $17,500 for 2014. Contributions are matched by the Company at a rate of 100% up to 6% of participant's compensation, subject to IRS limitations. Any amounts over the IRS limits are contributed to and matched by the Company into a nonqualified supplemental executive retirement plan for employees eligible to participate in such nonqualified plan. The Company also makes a core contribution of 6% of the participant's compensation to the qualified plan, subject to IRS limitations, and the nonqualified supplemental executive retirement plan for eligible employees, regardless of whether the employee contributes to the plan(s). Employees become fully vested in Company contributions after one year of service, as defined in the plan. Plan eligibility is immediate upon hire. The Company also maintains similar non-qualified plans for non-U.S. employees.
The Company recognized defined contribution expenses of $11 million, $10 million and $9 million for the years ended December 31, 2014, 2013 and 2012, respectively.
Cash-Based Compensation
Performance Retention Plan
The Company has established the Assured Guaranty Ltd. Performance Retention Plan (“PRP”) which permits the grant of cash based awards to selected employees. PRP awards may be treated as nonqualified deferred compensation subject to the rules of Internal Revenue Code Section 409A. The PRP is a sub-plan under the Company's Long-Term Incentive Plan (enabling awards under the plan to be performance based compensation exempt from the $1 million limit on tax deductible compensation).
Generally, each PRP award is divided into three installments, with 25% of the award allocated to a performance period that includes the year of the award and the next year, 25% of the award allocated to a performance period that includes the year of the award and the next two years, and 50% of the award allocated to a performance period that includes the year of the award and the next three years. Each installment of an award vests if the participant remains employed through the end of the performance period for that installment. Awards may vest upon the occurrence of other events as set forth in the plan documents. Payment for each performance period is made at the end of that performance period. One half of each installment is increased or decreased in proportion to the increase or decrease of adjusted book value per share during the performance period, and one half of each installment is increased or decreased in proportion to the operating return on equity during the performance period. Operating return on equity and adjusted book value are defined in each PRP award agreement.
A payment otherwise subject to the $1 million limit on tax deductible compensation, will not be made unless performance satisfies a minimum threshold.
As described above, the performance measures used to determine the amounts distributable under the PRP are based on the Company's operating return on equity and growth in adjusted book value per share, as defined. Adjustments may be made by the AGL Compensation Committee at any time before distribution, except that, for certain senior executive officers, any adjustment made after the grant of the award may decrease but may not increase the amount of the distribution.
In the event of a corporate transaction involving the Company, including, without limitation, any share dividend, share split, extraordinary cash dividend, recapitalization, reorganization, merger, amalgamation, consolidation, split-up, spin-off, sale of assets or subsidiaries, combination or exchange of shares, the Compensation Committee may adjust the calculation of the Company's adjusted book value and operating return on equity as the Compensation Committee deems necessary or desirable in order to preserve the benefits or potential benefits of PRP awards.
The Company recognized performance retention plan expenses of $15 million, $17 million and $13 million for the years ended December 31, 2014, 2013 and 2012, respectively.

Other_Comprehensive_Income

Other Comprehensive Income	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Other Comprehensive Income	Other Comprehensive Income
	The following tables present the changes in each component of AOCI and the effect of significant reclassifications out of AOCI on the respective line items in net income.
	Changes in Accumulated Other Comprehensive Income by Component
	Year Ended December 31, 2014
		Net Unrealized			Net Unrealized			Cumulative			Cash Flow Hedge			Total Accumulated
		Gains (Losses) on			Gains (Losses) on			Translation						Other
		Investments with no Other-Than-Temporary Impairment			Investments with Other-Than-Temporary Impairment			Adjustment						Comprehensive
														Income
		(in millions)
	Balance, December 31, 2013	$	178		$	(24	)	$	(3	)	$	9		$	160
	Other comprehensive income (loss) before reclassifications	196			(20		)	(7		)	—			169
	Amounts reclassified from AOCI to:
	Net realized investment gains (losses)	(12		)	74			—			—			62
	Interest expense	—			—			—			0			0
	Total before tax	(12		)	74			—			0			62
	Tax (provision) benefit	5			(26		)	—			0			(21		)
	Total amount reclassified from AOCI, net of tax	(7		)	48			—			0			41
	Net current period other comprehensive income (loss)	189			28			(7		)	0			210
	Balance, December 31, 2014	$	367		$	4		$	(10	)	$	9		$	370
	Changes in Accumulated Other Comprehensive Income by Component
	Year Ended December 31, 2013
		Net Unrealized			Net Unrealized			Cumulative			Cash Flow Hedge			Total Accumulated
		Gains (Losses) on			Gains (Losses) on			Translation						Other
		Investments with no Other-Than-Temporary Impairment			Investments with Other-Than-Temporary Impairment			Adjustment						Comprehensive
														Income
		(in millions)
	Balance, December 31, 2012	$	517		$	(5	)	$	(6	)	$	9		$	515
	Other comprehensive income (loss) before reclassifications	(309		)	(35		)	3			—			(341		)
	Amounts reclassified from AOCI to:
	Net realized investment gains (losses)	(43		)	24			—			—			(19		)
	Interest expense	—			—			—			(1		)	(1		)
	Total before tax	(43		)	24			—			(1		)	(20		)
	Tax (provision) benefit	13			(8		)	—			1			6
	Total amount reclassified from AOCI, net of tax	(30		)	16			—			0			(14		)
	Net current period other comprehensive income (loss)	(339		)	(19		)	3			0			(355		)
	Balance, December 31, 2013	$	178		$	(24	)	$	(3	)	$	9		$	160
	Changes in Accumulated Other Comprehensive Income by Component
	Year Ended December 31, 2012
		Net Unrealized			Net Unrealized			Cumulative			Cash Flow Hedge			Total Accumulated
		Gains (Losses) on			Gains (Losses) on			Translation						Other
		Investments with no Other-Than-Temporary Impairment			Investments with Other-Than-Temporary Impairment			Adjustment						Comprehensive
														Income
		(in millions)
	Balance, December 31, 2011	$	365		$	2		$	(8	)	$	9		$	368
	Other comprehensive income (loss)	152			(7		)	2			0			147
	Balance, December 31, 2012	$	517		$	(5	)	$	(6	)	$	9		$	515

Subsidiary_Information

Subsidiary Information	12 Months Ended
	Dec. 31, 2014
Subsidiary Information [abstract]
Subsidiary Information	Subsidiary Information
	The following tables present the condensed consolidating financial information for AGUS and AGMH, wholly-owned subsidiaries of AGL, which have issued publicly traded debt securities (see Note 17, Long-Term Debt and Credit Facilities, for the full description of AGUS and AGMH debt and the related AGL guarantees for such debt) as of December 31, 2014 and December 31, 2013 and for the years ended December 31, 2014, 2013 and 2012. The information for AGUS and AGMH presents its subsidiaries on the equity method of accounting.
	CONDENSED CONSOLIDATING BALANCE SHEET
	AS OF DECEMBER 31, 2014
	(in millions)
		Assured			AGUS			AGMH			Other			Consolidating			Assured
		Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
		(Parent)															(Consolidated)
	ASSETS
	Total investment portfolio and cash	$	126		$	204		$	47		$	11,382		$	(300	)	$	11,459
	Investment in subsidiaries	5,612			5,072			3,965			339			(14,988		)	—
	Premiums receivable, net of commissions payable	—			—			—			864			(135		)	729
	Ceded unearned premium reserve	—			—			—			1,469			(1,088		)	381
	Deferred acquisition costs	—			—			—			186			(65		)	121
	Reinsurance recoverable on unpaid losses	—			—			—			338			(260		)	78
	Credit derivative assets	—			—			—			277			(209		)	68
	Deferred tax asset, net	—			54			—			295			(89		)	260
	Intercompany receivable	—			—			—			90			(90		)	—
	Financial guaranty variable interest entities’ assets, at fair value	—			—			—			1,402			—			1,402
	Other	27			77			27			538			(242		)	427
	TOTAL ASSETS	$	5,765		$	5,407		$	4,039		$	17,180		$	(17,466	)	$	14,925
	LIABILITIES AND SHAREHOLDERS’ EQUITY
	Unearned premium reserves	$	—		$	—		$	—		$	5,328		$	(1,067	)	$	4,261
	Loss and LAE reserve	—			—			—			1,066			(267		)	799
	Long-term debt	—			847			437			19			—			1,303
	Intercompany payable	—			90			—			300			(390		)	—
	Credit derivative liabilities	—			—			—			1,172			(209		)	963
	Deferred tax liabilities, net	—			—			94			—			(94		)	—
	Financial guaranty variable interest entities’ liabilities, at fair value	—			—			—			1,419			—			1,419
	Other	7			9			16			764			(374		)	422
	TOTAL LIABILITIES	7			946			547			10,068			(2,401		)	9,167
	TOTAL SHAREHOLDERS’ EQUITY ATTRIBUTABLE TO ASSURED GUARANTY LTD.	5,758			4,461			3,492			6,773			(14,726		)	5,758
	Noncontrolling interest	—			—			—			339			(339		)	—
	TOTAL SHAREHOLDERS’ EQUITY	5,758			4,461			3,492			7,112			(15,065		)	5,758
	TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$	5,765		$	5,407		$	4,039		$	17,180		$	(17,466	)	$	14,925
	CONDENSED CONSOLIDATING BALANCE SHEET
	AS OF DECEMBER 31, 2013
	(in millions)
		Assured			AGUS			AGMH			Other			Consolidating			Assured
		Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
		(Parent)															(Consolidated)
	ASSETS
	Total investment portfolio and cash	$	33		$	186		$	42		$	11,008		$	(300	)	$	10,969
	Investment in subsidiaries	5,066			4,191			3,574			289			(13,120		)	—
	Premiums receivable, net of commissions payable	—			—			—			1,025			(149		)	876
	Ceded unearned premium reserve	—			—			—			1,598			(1,146		)	452
	Deferred acquisition costs	—			—			—			198			(74		)	124
	Reinsurance recoverable on unpaid losses	—			—			—			170			(134		)	36
	Credit derivative assets	—			—			—			482			(388		)	94
	Deferred tax asset, net	—			97			—			681			(90		)	688
	Intercompany receivable	—			—			—			90			(90		)	—
	Financial guaranty variable interest entities’ assets, at fair value	—			—			—			2,565			—			2,565
	Other	23			17			31			638			(226		)	483
	TOTAL ASSETS	$	5,122		$	4,491		$	3,647		$	18,744		$	(15,717	)	$	16,287
	LIABILITIES AND SHAREHOLDERS’ EQUITY
	Unearned premium reserves	$	—		$	—		$	—		$	5,720		$	(1,125	)	$	4,595
	Loss and LAE reserve	—			—			—			733			(141		)	592
	Long-term debt	—			348			430			38			—			816
	Intercompany payable	—			90			—			300			(390		)	—
	Credit derivative liabilities	—			—			—			2,175			(388		)	1,787
	Deferred tax liabilities, net	—			—			95			—			(95		)	—
	Financial guaranty variable interest entities’ liabilities, at fair value	—			—			—			2,871			—			2,871
	Other	7			7			16			853			(372		)	511
	TOTAL LIABILITIES	7			445			541			12,690			(2,511		)	11,172
TOTAL SHAREHOLDERS’ EQUITY ATTRIBUTABLE TO ASSURED GUARANTY LTD.	5,115			4,046			3,106			5,765			(12,917		)	5,115
Noncontrolling interest	—			—			—			289			(289		)	—
TOTAL SHAREHOLDERS’ EQUITY	5,115			4,046			3,106			6,054			(13,206		)	5,115
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$	5,122		$	4,491		$	3,647		$	18,744		$	(15,717	)	$	16,287
CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS
AND COMPREHENSIVE INCOME
FOR THE YEAR ENDED DECEMBER 31, 2014
(in millions)
	Assured			AGUS			AGMH			Other			Consolidating			Assured
	Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
	(Parent)															(Consolidated)
REVENUES
Net earned premiums	$	—		$	—		$	—		$	566		$	4		$	570
Net investment income	0			0			1			412			(10		)	403
Net realized investment gains (losses)	0			0			0			(58		)	(2		)	(60		)
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements	—			—			—			23			—			23
Net unrealized gains (losses)	—			—			—			800			—			800
Net change in fair value of credit derivatives	—			—			—			823			—			823
Other	0			0			—			259			(1		)	258
TOTAL REVENUES	0			0			1			2,002			(9		)	1,994
EXPENSES
Loss and LAE	—			—			—			122			4			126
Amortization of deferred acquisition costs	—			—			—			33			(8		)	25
Interest expense	—			40			54			16			(18		)	92
Other operating expenses	31			1			1			195			(8		)	220
TOTAL EXPENSES	31			41			55			366			(30		)	463
INCOME (LOSS) BEFORE INCOME TAXES AND EQUITY IN NET EARNINGS OF SUBSIDIARIES	(31		)	(41		)	(54		)	1,636			21			1,531
Total (provision) benefit for income taxes	—			14			19			(469		)	(7		)	(443		)
Equity in net earnings of subsidiaries	$	1,119		$	983		$	513		$	32		$	(2,647	)	—
NET INCOME (LOSS)	1,088			956			478			1,199			(2,633		)	1,088
Less: noncontrolling interest	—			—			—			32			(32		)	—
NET INCOME (LOSS) ATTRIBUTABLE TO ASSURED GUARANTY LTD.	$	1,088		$	956		$	478		$	1,167		$	(2,601	)	$	1,088
COMPREHENSIVE INCOME (LOSS)	$	1,298		$	1,114		$	577		$	1,570		$	(3,261	)	$	1,298
CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS
AND COMPREHENSIVE INCOME
FOR THE YEAR ENDED DECEMBER 31, 2013
(in millions)
	Assured			AGUS			AGMH			Other			Consolidating			Assured
	Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
	(Parent)															(Consolidated)
REVENUES
Net earned premiums	$	—		$	—		$	—		$	740		$	12		$	752
Net investment income	0			0			1			408			(16		)	393
Net realized investment gains (losses)	0			0			0			87			(35		)	52
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements	—			—			—			(42		)	—			(42		)
Net unrealized gains (losses)	—			—			—			107			—			107
Net change in fair value of credit derivatives	—			—			—			65			—			65
Other	—			—			—			348			(2		)	346
TOTAL REVENUES	0			0			1			1,648			(41		)	1,608
EXPENSES
Loss and LAE	—			—			—			144			10			154
Amortization of deferred acquisition costs	—			—			—			12			0			12
Interest expense	—			28			54			20			(20		)	82
Other operating expenses	22			1			1			199			(5		)	218
TOTAL EXPENSES	22			29			55			375			(15		)	466
INCOME (LOSS) BEFORE INCOME TAXES AND EQUITY IN NET EARNINGS OF SUBSIDIARIES	(22		)	(29		)	(54		)	1,273			(26		)	1,142
Total (provision) benefit for income taxes	—			9			17			(387		)	27			(334		)
Equity in net earnings of subsidiaries	830			768			701			19			(2,318		)	—
NET INCOME (LOSS)	808			748			664			905			(2,317		)	808
Less: noncontrolling interest	—			—			—			19			(19		)	—
NET INCOME (LOSS) ATTRIBUTABLE TO ASSURED GUARANTY LTD.	$	808		$	748		$	664		$	886		$	(2,298	)	$	808
COMPREHENSIVE INCOME (LOSS)	$	453		$	522		$	515		$	309		$	(1,346	)	$	453
CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS
AND COMPREHENSIVE INCOME
FOR THE YEAR ENDED DECEMBER 31, 2012
(in millions)
	Assured			AGUS			AGMH			Other			Consolidating			Assured
	Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
	(Parent)															(Consolidated)
REVENUES
Net earned premiums	$	—		$	—		$	—		$	833		$	20		$	853
Net investment income	0			—			1			422			(19		)	404
Net realized investment gains (losses)	—			—			—			1			—			1
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements	—			—			—			(108		)	—			(108		)
Net unrealized gains (losses)	—			—			—			(477		)	—			(477		)
Net change in fair value of credit derivatives	—			—			—			(585		)	—			(585		)
Other	—			—			—			284			(3		)	281
TOTAL REVENUES	0			—			1			955			(2		)	954
EXPENSES
Loss and LAE	—			—			—			509			(5		)	504
Amortization of deferred acquisition costs	—			—			—			28			(14		)	14
Interest expense	—			35			54			22			(19		)	92
Other operating expenses	21			2			1			194			(6		)	212
TOTAL EXPENSES	21			37			55			753			(44		)	822
INCOME (LOSS) BEFORE INCOME TAXES AND EQUITY IN NET EARNINGS OF SUBSIDIARIES	(21		)	(37		)	(54		)	202			42			132
Total (provision) benefit for income taxes	—			13			19			(38		)	(16		)	(22		)
Equity in net earnings of subsidiaries	131			177			424			153			(885		)	—
NET INCOME (LOSS)	$	110		$	153		$	389		$	317		$	(859	)	$	110
COMPREHENSIVE INCOME (LOSS)	$	257		$	266		$	465		$	577		$	(1,308	)	$	257
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
FOR THE YEAR ENDED DECEMBER 31, 2014
(in millions)
	Assured			AGUS			AGMH			Other			Consolidating			Assured
	Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
	(Parent)															(Consolidated)
Net cash flows provided by (used in) operating activities	$	758		$	223		$	144		$	663		$	(1,211	)	$	577
Cash flows from investing activities
Fixed-maturity securities:
Purchases	—			(540		)	(8		)	(2,253		)	—			(2,801		)
Sales	—			464			10			777			—			1,251
Maturities	—			6			1			870			—			877
Sales (purchases) of short-term investments, net	(93		)	(15		)	(3		)	269			—			158
Net proceeds from financial guaranty variable entities’ assets										408			—			408
Intercompany debt	—			—			—			—			—			—
Investment in subsidiary	—			—			50			—			(50		)	—
Other	—			—			—			11			—			11
Net cash flows provided by (used in) investing activities	(93		)	(85		)	50			82			(50		)	(96		)
Cash flows from financing activities
Return of capital	—			—			—			(50		)	50			—
Capital contribution from parent	—			—			—			—			—			—
Dividends paid	(76		)	(700		)	(190		)	(321		)	1,211			(76		)
Repurchases of common stock	(590		)	—			—			—			—			(590		)
Share activity under option and incentive plans	1			—			—			—			—			1
Net paydowns of financial guaranty variable entities’ liabilities	—			—			—			(396		)	—			(396		)
Net proceeds from issuance of long-term debt	—			495			—			—			—			495
Payment of long-term debt	—			—			—			(19		)	—			(19		)
Intercompany debt	—			—			—			—			—			—
Net cash flows provided by (used in) financing activities	(665		)	(205		)	(190		)	(786		)	1,261			(585		)
Effect of exchange rate changes	—			—			—			(5		)	—			(5		)
Increase (decrease) in cash	—			(67		)	4			(46		)	—			(109		)
Cash at beginning of period	0			67			0			117			—			184
Cash at end of period	$	0		$	0		$	4		$	71		$	—		$	75
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
FOR THE YEAR ENDED DECEMBER 31, 2013
(in millions)
	Assured			AGUS			AGMH			Other			Consolidating			Assured
	Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
	(Parent)															(Consolidated)
Net cash flows provided by (used in) operating activities	$	128		$	178		$	133		$	347		$	(542	)	$	244
Cash flows from investing activities
Fixed-maturity securities:
Purchases	—			(93		)	(26		)	(1,832		)	65			(1,886		)
Sales	176			1			25			892			(65		)	1,029
Maturities	29			3			2			849			—			883
Sales (purchases) of short-term investments, net	7			(28		)	(15		)	(51		)	—			(87		)
Net proceeds from financial guaranty variable entities’ assets	—			—			—			663			—			663
Intercompany debt	—			—			—			7			(7		)	—
Investment in subsidiary	—			0			49			—			(49		)	—
Other	—			—			—			79			—			79
Net cash flows provided by (used in) investing activities	212			(117		)	35			607			(56		)	681
Cash flows from financing activities																—
Return of capital	—			—			—			(50		)	50			—
Capital contribution from parent	—			—			—			1			(1		)	—
Dividends paid	(75		)	—			(168		)	(374		)	542			(75		)
Repurchases of common stock	(264		)	—			—			—			—			(264		)
Share activity under option and incentive plans	(1		)	—			—			—			—			(1		)
Net paydowns of financial guaranty variable entities’ liabilities	—			—			—			(511		)	—			(511		)
Payment of long-term debt	—			—			—			(27		)	—			(27		)
Intercompany debt	—			(7		)	—			—			7			—
Net cash flows provided by (used in) financing activities	(340		)	(7		)	(168		)	(961		)	598			(878		)
Effect of exchange rate changes	—			—			—			(1		)	—			(1		)
Increase (decrease) in cash	0			54			—			(8		)	—			46
Cash at beginning of period	—			13			0			125			—			138
Cash at end of period	$	0		$	67		$	0		$	117		$	—		$	184
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
FOR THE YEAR ENDED DECEMBER 31, 2012
(in millions)
	Assured			AGUS			AGMH			Other			Consolidating			Assured
	Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
	(Parent)															(Consolidated)
Net cash flows provided by (used in) operating activities	$	138		$	6		$	20		$	5		$	(334	)	$	(165	)
Cash flows from investing activities
Fixed-maturity securities:
Purchases	(211		)	(1		)	(13		)	(1,424		)	—			(1,649		)
Sales	—			—			13			899			—			912
Maturities	3			—			6			1,096			—			1,105
Sales (purchases) of short-term investments, net	(7		)	27			26			(17		)	—			29
Net proceeds from financial guaranty variable entities’ assets	—			—			—			545			—			545
Acquisition of MAC	—			(91		)	—			—			—			(91		)
Intercompany debt	—			—			—			(173		)	173			—
Investment in subsidiary	—			—			46			—			(46		)	—
Other	—			—			—			92			—			92
Net cash flows provided by (used in) investing activities	(215		)	(65		)	78			1,018			127			943
Cash flows from financing activities
Issuance of common stock	173			—			—			—			—			173
Return of capital	—			—			—			(50		)	50			—
Capital contribution from parent	—			—			—			4			(4		)	—
Dividends paid	(69		)	—			(98		)	(236		)	334			(69		)
Repurchases of common stock	(24		)	—			—			—			—			(24		)
Share activity under option and incentive plans	(3		)	—			—			—			—			(3		)
Net paydowns of financial guaranty variable entities’ liabilities	—			—			—			(724		)	—			(724		)
Payment of long-term debt	—			(173		)	—			(36		)	—			(209		)
Intercompany debt	—			173			—			—			(173		)	—
Net cash flows provided by (used in) financing activities	77			—			(98		)	(1,042		)	207			(856		)
Effect of exchange rate changes	—			—			—			1			—			1
Increase (decrease) in cash	—			(59		)	—			(18		)	—			(77		)
Cash at beginning of period	—			72			0			143			—			215
Cash at end of period	$	—		$	13		$	0		$	125		$	—		$	138

Quarterly_Financial_Informatio

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information (Unaudited)	Quarterly Financial Information (Unaudited)
	A summary of selected quarterly information follows:
	2014		First			Second			Third			Fourth			Full
			Quarter			Quarter			Quarter			Quarter			Year
			(dollars in millions, except per share data)
	Revenues
	Net earned premiums		$	132		$	136		$	144		$	158		$	570
	Net investment income		103			96			102			102			403
	Net realized investment gains (losses)		2			(8		)	(19		)	(35		)	(60		)
	Net change in fair value of credit derivatives		(211		)	103			255			676			823
	Fair value gains (losses) on CCS		(9		)	(6		)	4			0			(11		)
	Fair value gains (losses) on FG VIEs		157			25			50			23			255
	Other income (loss)		21			7			(11		)	(3		)	14
	Expenses
	Loss and LAE		41			57			(44		)	72			126
	Amortization of DAC		5			3			4			13			25
	Interest expense		20			20			27			25			92
	Other operating expenses		60			55			50			55			220
	Income (loss) before provision for income taxes		69			218			488			756			1,531
	Provision (benefit) for income taxes		27			59			133			224			443
	Net income (loss)		42			159			355			532			1,088
	Earnings (loss) per share(1):
	Basic		$	0.23		$	0.89		$	2.1		$	3.3		$	6.3
	Diluted		$	0.23		$	0.89		$	2.09		$	3.28		$	6.26
	Dividends per share		$	0.11		$	0.11		$	0.11		$	0.11		$	0.44
	2013		First			Second			Third			Fourth			Full
			Quarter			Quarter			Quarter			Quarter			Year
			(dollars in millions, except per share data)
	Revenues
	Net earned premiums		$	248		$	163		$	159		$	182		$	752
	Net investment income		94			93			99			107			393
	Net realized investment gains (losses)		28			2			(7		)	29			52
	Net change in fair value of credit derivatives		(592		)	74			354			229			65
	Fair value gains (losses) on CCS		(10		)	(3		)	9			14			10
	Fair value gains (losses) on FG VIEs		70			143			40			93			346
	Other income (loss)		(14		)	(7		)	16			(5		)	(10		)
	Expenses
	Loss and LAE		(48		)	62			55			85			154
	Amortization of DAC		3			1			4			4			12
	Interest expense		21			21			21			19			82
	Other operating expenses		60			52			54			52			218
	Income (loss) before provision for income taxes		(212		)	329			536			489			1,142
	Provision (benefit) for income taxes		(68		)	110			152			140			334
	Net income (loss)		(144		)	219			384			349			808
	Earnings (loss) per share(1):
	Basic		$	(0.74	)	$	1.17		$	2.1		$	1.91		$	4.32
	Diluted		$	(0.74	)	$	1.16		$	2.09		$	1.9		$	4.3
	Dividends per share		$	0.1		$	0.1		$	0.1		$	0.1		$	0.4
	____________________
	-1	Per share amounts for the quarters and the full years have each been calculated separately. Accordingly, quarterly amounts may not sum up to the annual amounts because of differences in the average common shares outstanding during each period and, with regard to diluted per share amounts only, because of the inclusion of the effect of potentially dilutive securities only in the periods in which such effect would have been dilutive.

Business_and_Basis_of_Presenta1

Business and Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Significant Accounting Policies	The consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and, in the opinion of management, reflect all adjustments that are of a normal recurring nature, necessary for a fair statement of the financial condition, results of operations and cash flows of the Company and its consolidated financial guaranty variable interest entities (“FG VIEs”) for the periods presented. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Consolidation	The consolidated financial statements include the accounts of AGL, its direct and indirect subsidiaries, (collectively, the “Subsidiaries”), and its consolidated FG VIEs. Intercompany accounts and transactions between and among all consolidated entities have been eliminated.
Reclassification	Certain prior year balances have been reclassified to conform to the current year's presentation.
Foreign Currency Transactions and Translations	The Company revalues assets, liabilities, revenue and expenses denominated in non-U.S. currencies into U.S. dollars using applicable exchange rates. Gains and losses relating to translating foreign functional currency financial statements for U.S. GAAP reporting are recorded in other comprehensive income (loss) ("OCI"). Gains and losses relating to transactions in foreign denominations in subsidiaries where the functional currency is the U.S. dollar, are reported in the consolidated statement of operations.
Revenue Recognition, Deferred Revenue	Accounting for financial guaranty contracts that meet the scope exception under derivative accounting guidance are subject to industry specific guidance for financial guaranty insurance. The accounting for contracts that fall under the financial guaranty insurance definition are consistent whether the contract was written on a direct basis, assumed from another financial guarantor under a reinsurance treaty, ceded to another insurer under a reinsurance treaty, or acquired in a business combination.
	Premium receivables comprise the present value of contractual or expected future premium collections discounted using the risk-free rate. Unearned premium reserve represents deferred premium revenue, less claim payments and recoveries received that have not yet been recognized in the statement of operations (“contra-paid”). The following discussion relates to the deferred premium revenue component of the unearned premium reserve, while the contra-paid is discussed in Note 7, Financial Guaranty Insurance Losses.
	The amount of deferred premium revenue at contract inception is determined as follows:
	•	For premiums received upfront on financial guaranty insurance contracts that were originally underwritten by the Company, deferred premium revenue is equal to the amount of cash received. Upfront premiums typically relate to public finance transactions.
	•	For premiums received in installments on financial guaranty insurance contracts that were originally underwritten by the Company, deferred premium revenue is the present value of either (1) contractual premiums due or (2) in cases where the underlying collateral is comprised of homogeneous pools of assets, the expected premiums to be collected over the life of the contract. To be considered a homogeneous pool of assets, prepayments must be contractually prepayable, the amount of prepayments must be probable, and the timing and amount of prepayments must be reasonably estimable. When the Company adjusts prepayment assumptions or expected premium collections, an adjustment is recorded to the deferred premium revenue, with a corresponding adjustment to the premium receivable, and prospective changes are recognized in premium revenues. Premiums receivable are discounted at the risk-free rate at inception and such discount rate is updated only when changes to prepayment assumptions are made that change the expected date of final maturity. Installment premiums typically relate to structured finance transactions, where the insurance premium rate is determined at the inception of the contract but the insured par is subject to prepayment throughout the life of the transaction.
	•	For financial guaranty insurance contracts acquired in a business combination, deferred premium revenue is equal to the fair value of the Company's stand-ready obligation portion of the insurance contract at the date of acquisition based on what a hypothetical similarly rated financial guaranty insurer would have charged for the contract at that date and not the actual cash flows under the insurance contract. The amount of deferred premium revenue may differ significantly from cash collections due primarily to fair value adjustments recorded in connection with a business combination.
	The Company recognizes deferred premium revenue as earned premium over the contractual period or expected period of the contract in proportion to the amount of insurance protection provided. As premium revenue is recognized, a corresponding decrease to the deferred premium revenue is recorded. The amount of insurance protection provided is a function of the insured principal amount outstanding. Accordingly, the proportionate share of premium revenue recognized in a given reporting period is a constant rate calculated based on the relationship between the insured principal amounts outstanding in the reporting period compared with the sum of each of the insured principal amounts outstanding for all periods. When an insured financial obligation is retired before its maturity, the financial guaranty insurance contract is extinguished. Any nonrefundable deferred premium revenue related to that contract is accelerated and recognized as premium revenue. When a premium receivable balance is deemed uncollectible, it is written off to bad debt expense.
	For reinsurance assumed contracts, earned premiums reported in the Company's consolidated statements of operations are calculated based upon data received from ceding companies, however, some ceding companies report premium data between 30 and 90 days after the end of the reporting period. The Company estimates earned premiums for the lag period.  Differences between such estimates and actual amounts are recorded in the period in which the actual amounts are determined. When installment premiums are related to reinsurance assumed contracts, the Company assesses the credit quality and liquidity of the ceding companies and the impact of any potential regulatory constraints to determine the collectability of such amounts.
Expected Losses to be Paid	Accounting Policy
	Insurance Accounting
	For contracts accounted for as financial guaranty insurance, loss and LAE reserve is recorded only to the extent and for the amount that expected losses to be paid exceed unearned premium reserve. As a result, the Company has expected loss to be paid that have not yet been expensed. Such amounts will be recognized in future periods as deferred premium revenue amortizes into income. Expected loss to be paid is important from a liquidity perspective in that it represents the present value of amounts that the Company expects to pay or recover in future periods, regardless of the accounting model. Expected loss to be paid is an important measure used by management to analyze the net economic loss on all contacts. Expected loss to be expensed is important because it presents the Company's projection of incurred losses that will be recognized in future periods (excluding accretion of discount). See Note 7, Financial Guaranty Insurance Losses.
	Derivative Accounting, at Fair Value
	For contracts that do not meet the financial guaranty scope exception in the derivative accounting guidance (primarily due to the fact that the insured is not required to be exposed to the insured risk throughout the life of the contract), the Company records such credit derivative contracts at fair value on the consolidated balance sheet with changes in fair value recorded in the consolidated statement of operations. The fair value recorded on the balance sheet represents an exit price in a hypothetical market because the Company does not trade its credit derivative contracts. The fair value is determined using significant Level 3 inputs in an internally developed model while the expected loss to be paid (which represents the net present value of expected cash outflows) uses methodologies and assumptions consistent with financial guaranty insurance expected losses to be paid. See Note 8, Fair Value Measurement and Note 9, Financial Guaranty Contracts Accounted for as Credit Derivatives.
	VIE Consolidation, at Fair Value
	For financial guaranty insurance contracts issued on the debt of variable interest entities over which the Company is deemed to be the primary beneficiary due to its control rights, as defined in GAAP, the Company consolidates the FG VIE. The Company carries the assets and liabilities of the FG VIEs at fair value under the fair value option election. Management assesses the losses on the insured debt of the consolidated FG VIEs in the same manner as other financial guaranty insurance and credit derivative contracts. See Note 10, Consolidated Variable Interest Entities.
Policy Acquisition Costs	Policy acquisition costs that are directly related and essential to successful insurance contract acquisition and ceding commission income on ceded reinsurance contracts are deferred for contracts accounted for as insurance. Amortization of deferred policy acquisition costs includes the accretion of discount on ceding commission income and expense. Acquisition costs associated with derivative contracts are not deferred.
	Direct costs related to the acquisition of new and renewal contracts that result directly from and are essential to the contract transaction are capitalized. These costs include expenses such as ceding commissions expense on assumed reinsurance contracts and the cost of underwriting personnel attributable to successful underwriting efforts. Ceding commission expense on assumed reinsurance contracts and ceding commission income on ceded reinsurance contracts that are associated with premiums received in installments are calculated at their contractually defined rates and included in deferred acquisition costs ("DAC"), with a corresponding offset to net premiums receivable or reinsurance balances payable. Management uses its judgment in determining the type and amount of costs to be deferred. The Company conducts an annual study to determine which operating costs qualify for deferral. Costs incurred for soliciting potential customers, market research, training, administration, unsuccessful acquisition efforts, and product development as well as all overhead type costs are charged to expense as incurred. DAC is amortized in proportion to net earned premiums. When an insured obligation is retired early, the remaining related DAC is expensed at that time.
	Expected losses, which include loss adjustment expenses (“LAE”), investment income, and the remaining costs of servicing the insured or reinsured business, are considered in determining the recoverability of DAC.
Fair Value of Financial Instruments	During 2014, no changes were made to the Company’s valuation models that had or are expected to have, a material impact on the Company’s consolidated balance sheets or statements of operations and comprehensive income.
	The Company’s methods for calculating fair value produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. The use of different methodologies or assumptions to determine fair value of certain financial instruments could result in a different estimate of fair value at the reporting date.
	The fair value hierarchy is determined based on whether the inputs to valuation techniques used to measure fair value are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect Company estimates of market assumptions. The fair value hierarchy prioritizes model inputs into three broad levels as follows, with Level 1 being the highest and Level 3 the lowest. An asset or liability’s categorization within the fair value hierarchy is based on the lowest level of significant input to its valuation.
	Level 1—Quoted prices for identical instruments in active markets. The Company generally defines an active market as a market in which trading occurs at significant volumes. Active markets generally are more liquid and have a lower bid-ask spread than an inactive market.
	Level 2—Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and observable inputs other than quoted prices, such as interest rates or yield curves and other inputs derived from or corroborated by observable market inputs.
	Level 3—Model derived valuations in which one or more significant inputs or significant value drivers are unobservable. Financial instruments are considered Level 3 when their values are determined using pricing models, discounted cash flow methodologies or similar techniques and at least one significant model assumption or input is unobservable. Level 3 financial instruments also include those for which the determination of fair value requires significant management judgment or estimation.
	Transfers between Levels 1, 2 and 3 are recognized at the end of the period when the transfer occurs. The Company reviews the classification between Levels 1, 2 and 3 quarterly to determine whether a transfer is necessary.
Salvage and Subrogation Recoverable	When the Company becomes entitled to the cash flow from the underlying collateral of an insured credit under salvage and subrogation rights as a result of a claim payment or estimated future claim payment, it reduces the expected loss to be paid on the contract. Such reduction in expected loss to be paid can result in one of the following:
	•	a reduction in the corresponding loss and LAE reserve with a benefit to the income statement,
	•	no entry recorded, if “total loss” is not in excess of deferred premium revenue, or
	•	the recording of a salvage asset with a benefit to the income statement if the transaction is in a net recovery position at the reporting date.
	The Company recognizes the expected recovery of claim payments (including recoveries from settlement with R&W providers) made by an acquired subsidiary prior to the date of acquisition, consistent with its policy for recognizing recoveries on all financial guaranty insurance contracts. To the extent that the estimated amount of recoveries increases or decreases, due to changes in facts and circumstances, including the examination of additional loan files and our experience in recovering loans put back to the originator, the Company would recognize a benefit or expense consistent with how changes in the expected recovery of all other claim payments are recorded. The ceded component of salvage and subrogation recoverable is recorded in the line item reinsurance balances payable.
Expected Loss to be Expensed	Expected loss to be expensed represents past or expected future net claim payments that have not yet been expensed. Such amounts will be expensed in future periods as deferred premium revenue amortizes into income on financial guaranty insurance policies. Expected loss to be expensed is the Company's projection of incurred losses that will be recognized in future periods, excluding accretion of discount.
Credit Derivatives	Credit derivatives are recorded at fair value. Changes in fair value are recorded in “net change in fair value of credit derivatives” on the consolidated statement of operations. Realized gains and other settlements on credit derivatives include credit derivative premiums received and receivable for credit protection the Company has sold under its insured CDS contracts, premiums paid and payable for credit protection the Company has purchased, claims paid and payable and received and receivable related to insured credit events under these contracts, ceding commissions expense or income and realized gains or losses related to their early termination. Fair value of credit derivatives is reflected as either net assets or net liabilities determined on a contract by contract basis in the Company's consolidated balance sheets. See Note 8, Fair Value Measurement, for a discussion on the fair value methodology for credit derivatives.
Consolidation, Variable Interest Entity	The Company evaluates whether it is the primary beneficiary of its VIEs. If the Company concludes that it is the primary beneficiary, it is required to consolidate the entire VIE in the Company's financial statements and eliminate the effects of the financial guaranty insurance contracts issued by AGM and AGC on the consolidated FG VIEs debt obligations.
	The primary beneficiary of a VIE is the enterprise that has both 1) the power to direct the activities of a VIE that most significantly impact the entity's economic performance; and 2) the obligation to absorb losses of the entity that could potentially be significant to the VIE or the right to receive benefits from the entity that could potentially be significant to the VIE.
	As part of the terms of its financial guaranty contracts, the Company obtains certain protective rights with respect to the VIE that are triggered by the occurrence of certain events, such as failure to be in compliance with a covenant due to poor deal performance or a deterioration in a servicer or collateral manager's financial condition. At deal inception, the Company typically is not deemed to control a VIE; however, once a trigger event occurs, the Company's control of the VIE typically increases. The Company continuously evaluates its power to direct the activities that most significantly impact the economic performance of VIEs that have debt obligations insured by the Company and, accordingly, where the Company is obligated to absorb VIE losses or receive benefits that could potentially be significant to the VIE. The Company obtains protective rights under its insurance contracts that give the Company additional controls over a VIE if there is either deterioration of deal performance or in the financial health of the deal servicer. The Company is deemed to be the control party for certain VIEs under GAAP, typically when its protective rights give it the power to both terminate and replace the deal servicer, which are characteristics specific to the Company's financial guaranty contracts. If the protective rights that could make the Company the control party have not been triggered, then the VIE is not consolidated. If the Company is deemed no longer to have those protective rights, the transaction is deconsolidated.
	The FG VIEs' liabilities that are insured by the Company are considered to be with recourse, because the Company guarantees the payment of principal and interest regardless of the performance of the related FG VIEs' assets. FG VIEs' liabilities that are not insured by the Company are considered to be without recourse, because the payment of principal and interest of these liabilities is wholly dependent on the performance of the FG VIEs' assets.
	The Company has limited contractual rights to obtain the financial records of its consolidated FG VIEs. The FG VIEs do not prepare separate GAAP financial statements; therefore, the Company compiles GAAP financial information for them based on trustee reports prepared by and received from third parties. Such trustee reports are not available to the Company until approximately 30 days after the end of any given period. The time required to perform adequate reconciliations and analyses of the information in these trustee reports results in a one quarter lag in reporting the FG VIEs' activities. The Company records the fair value of FG VIE assets and liabilities based on modeled prices. The Company updates the model assumptions each reporting period for the most recent available information, which incorporates the impact of material events that may have occurred since the quarter lag date. Interest income and interest expense are derived from the trustee reports and included in “fair value gains (losses) on FG VIEs” in the consolidated statement of operations. The Company has elected the fair value option for assets and liabilities classified as FG VIEs' assets and liabilities because the carrying amount transition method was not practical.
	The cash flows generated by the FG VIE assets, including R&W recoveries, are classified as cash flows from investing activities. Paydowns of FG liabilities are supported by the cash flows generated by FG VIE assets, and for liabilities with recourse, possibly claim payments made by AGM or AGC under its financial guaranty insurance contracts. Paydowns of FG liabilities both with and without recourse are classified as cash flows used in financing activities by the Company. Interest income, interest expense and other expenses of the FG VIE assets and liabilities are classified as operating cash flows. Claim payments made by AGC and AGM under the financial guaranty contracts issued to the FG VIEs are eliminated upon consolidation and therefore such claim payments are treated as paydowns of FG VIE liabilities as a financing activity as opposed to an operating activity of AGM and AGC.
Investments and Cash	The vast majority of the Company's investment portfolio is composed of fixed-maturity and short-term investments, classified as available-for-sale at the time of purchase (approximately 99% based on fair value at December 31, 2014), and therefore carried at fair value. Changes in fair value for other-than-temporarily-impaired ("OTTI") securities are bifurcated between credit losses and non-credit changes in fair value. The credit loss on OTTI securities is recorded in the statement of operations and the non-credit component of the change in fair value of securities, whether OTTI or not, is recorded in OCI. For securities where the Company has the intent to sell or it is more-likely-than-not that it will be required to sell the security before recovery, declines in fair value are recorded in the consolidated statements of operations.
	Credit losses reduce the amortized cost of impaired securities. The amortized cost basis is adjusted for accretion and amortization (using the effective interest method) with a corresponding entry recorded in net investment income.
	Realized gains and losses on sales of investments are determined using the specific identification method. Realized loss includes amounts recorded for other-than-temporary impairments on debt securities and the declines in fair value of securities for which the Company has the intent to sell the security or inability to hold until recovery of amortized cost.
	For mortgage‑backed securities, and any other holdings for which there is prepayment risk, prepayment assumptions are evaluated and revised as necessary. Any necessary adjustments due to changes in effective yields and maturities are recognized in net investment income.
	The Company purchases securities that it has insured, and for which it has expected losses to be paid, in order to mitigate the economic effect of insured losses ("loss mitigation securities"). These securities were purchased at a discount and are accounted for excluding the effects of the Company’s insurance.
	Short-term investments, which are those investments with a maturity of less than one year at time of purchase, are carried at fair value and include amounts deposited in money market funds.
	Other invested assets primarily include:
	•	preferred stocks, which are carried at fair value with changes in unrealized gains and losses recorded in OCI,
	•	trading securities, which are carried at fair value with unrealized gains and losses recorded in net income,
	•	a 50% equity investment acquired in a restructuring of an insured CDS carried at its proportionate share of the underlying entity's U.S. GAAP equity value.
Income Tax	The provision for income taxes consists of an amount for taxes currently payable and an amount for deferred taxes. Deferred income taxes are provided for temporary differences between the financial statement carrying amounts and tax bases of assets and liabilities, using enacted rates in effect for the year in which the differences are expected to reverse. A valuation allowance is recorded to reduce the deferred tax asset to an amount that is more likely than not to be realized.
	Non-interest‑bearing tax and loss bonds are purchased in the amount of the tax benefit that results from deducting contingency reserves as provided under Internal Revenue Code Section 832(e). The Company records the purchase of tax and loss bonds in deferred taxes.
	The Company recognizes tax benefits only if a tax position is “more likely than not” to prevail.
Reinsurance Accounting	For business assumed and ceded, the accounting model of the underlying direct financial guaranty contract dictates the accounting model used for the reinsurance contract (except for those eliminated as FG VIEs). For any assumed or ceded financial guaranty insurance premiums, the accounting model described in Note 4 is followed, for assumed and ceded financial guaranty insurance losses, the accounting model in Note 7 is followed. For any assumed or ceded credit derivative contracts, the accounting model in Note 9 is followed.
Debt	Long-term debt is recorded at principal amounts net of any unamortized original issue discount or premium and unamortized fair value adjustment for AGMH debt (as of the date of the AGMH acquisition). Discount is accreted into interest expense over the life of the applicable debt.
Earnings Per Share	The Company computes earnings per share ("EPS") using a two-class method by including participating securities which entitle their holders to receive nonforfeitable dividends or dividend equivalents before vesting. Restricted stock awards and share units under the AGC supplemental employee retirement plan ("SERP") plan are considered participating securities as they received non-forfeitable rights to dividends at the same rate as common stock.
	The two-class method of computing EPS is an earnings allocation formula that determines EPS for each class of common stock and participating security according to dividends declared (or accumulated) and participation rights in undistributed earnings. Basic EPS is then calculated by dividing net (loss) income available to common shareholders of Assured Guaranty by the weighted‑average number of common shares outstanding during the period. Diluted EPS adjusts basic EPS for the effects of restricted stock, stock options, equity units and other potentially dilutive financial instruments (“dilutive securities”), only in the periods in which such effect is dilutive. The effect of the dilutive securities is reflected in diluted EPS by application of the more dilutive of (1) the treasury stock method or (2) the two-class method assuming nonvested shares are not converted into common shares. With respect to the equity units, which were settled on June 1, 2012 (see Note 17, Long-Term Debt and Credit Facilities), the Company used the treasury stock method in computing diluted EPS. Equity forwards were included in the calculation of basic EPS when such forward contracts were satisfied and the holders thereof became common stock holders. The Company has a single class of common stock.
Share-based Compensation	Share-based compensation expense is based on the grant date fair value using the grant date closing price, the lattice, Monte Carlo or Black-Scholes pricing models. The Company amortizes the fair value of share-based awards on a straight-line basis over the requisite service periods of the awards, which are generally the vesting periods, with the exception of retirement‑eligible employees. For retirement-eligible employees, certain awards contain retirement provisions and therefore are amortized over the period through the date the employee first becomes eligible to retire and is no longer required to provide service to earn part or all of the award.
	The fair value of each award under the Assured Guaranty Ltd. Employee Stock Purchase Plan is estimated at the beginning of each offering period using the Black-Scholes option valuation model.
Compensation Related Costs	The expense for Performance Retention Plan awards is recognized straight-line over the requisite service period, with the exception of retirement eligible employees. For retirement eligible employees, the expense is recognized immediately.
Cash and Cash Equivalents	Cash consists of cash on hand and demand deposits. As a result of the lag in reporting FG VIEs, cash and short-term investments do not reflect cash outflow to the holders of the debt issued by the FG VIEs for claim payments made by the Company's insurance subsidiaries to the consolidated FG VIEs until the subsequent reporting period.
Loss and Loss Adjustment Expense Reserve	Loss and LAE Reserve
	Loss and LAE reserve reported on the balance sheet relates only to direct and assumed reinsurance contracts that are accounted for as insurance, substantially all of which are financial guaranty insurance contracts. The corresponding reserve ceded to reinsurers is reported as reinsurance recoverable on unpaid losses. As discussed in Note 8, Fair Value Measurement, contracts that meet the definition of a derivative, as well as consolidated FG VIE assets and liabilities, are recorded separately at fair value. Any expected losses related to consolidated FG VIEs are eliminated upon consolidation. Any expected losses on credit derivatives are not recorded as loss and LAE reserve on the consolidated balance sheet.
	Under financial guaranty insurance accounting, the sum of unearned premium reserve and loss and LAE reserve represents the Company's stand‑ready obligation. Unearned premium reserve is deferred premium revenue, less claim payments and recoveries received that have not yet been recognized in the statement of operations ("contra-paid"). At contract inception, the entire stand-ready obligation is represented by unearned premium reserve. A loss and LAE reserve for an insurance contract is only recorded when the expected loss to be paid net of contra-paid (“total losses”) exceed the deferred premium revenue, on a contract by contract basis.
	When a claim payment is made on a contract, it first reduces any recorded loss and LAE reserve. To the extent there is no loss and LAE reserve on a contract, which occurs when total losses are less than deferred premium revenue, or to the extent loss and LAE reserve is not sufficient to cover a claim payment, then such claim payment is recorded as “contra-paid,” which reduces the unearned premium reserve. The contra-paid is recognized in the line item “loss and LAE” in the consolidated statement of operations when and for the amount that total losses exceed the remaining deferred premium revenue on the insurance contract. Loss and LAE in the consolidated statement of operations is presented net of cessions to reinsurers.
Commitments and Contingencies	The Company establishes accruals for litigation and regulatory matters to the extent it is probable that a loss has been incurred and the amount of that loss can be reasonably estimated. For litigation and regulatory matters where a loss may be reasonably possible, but not probable, or is probable but not reasonably estimable, no accrual is established, but if the matter is material, it is disclosed, including matters discussed below. The Company reviews relevant information with respect to its litigation and regulatory matters on a quarterly, and annual basis and updates its accruals, disclosures and estimates of reasonably possible loss based on such reviews

Outstanding_Exposure_Tables

Outstanding Exposure (Tables)	12 Months Ended
	Dec. 31, 2014
Schedule of Insured Financial Obligations [Line Items]
Debt Service Outstanding	Debt Service Outstanding
		Gross Debt Service								Net Debt Service
		Outstanding								Outstanding
		December 31,				December 31,				December 31,				December 31,
		2014				2013				2014				2013
		(in millions)
	Public finance	$	587,245			$	650,924			$	553,612			$	610,011
	Structured finance	59,477				86,456				56,010				80,524
	Total financial guaranty	$	646,722			$	737,380			$	609,622			$	690,535
Financial Guaranty Portfolio by Internal Rating	Financial Guaranty Portfolio by Internal Rating
	As of December 31, 2014
			Public Finance							Public Finance							Structured Finance							Structured Finance							Total
			U.S.							Non-U.S.							U.S							Non-U.S
	Rating		Net Par				%			Net Par				%			Net Par				%			Net Par				%			Net Par			%
	Category		Outstanding							Outstanding							Outstanding							Outstanding							Outstanding
			(dollars in millions)
	AAA		$	4,082			1.3	%		$	615			2	%		$	20,037			48.7	%		$	5,409			59.6	%		$	30,143		7.5	%
	AA		90,464				28.1			2,785				8.9			8,213				19.9			503				5.5			101,965			25.3
	A		176,298				54.7			7,192				22.9			2,940				7.1			445				4.9			186,875			46.3
	BBB		43,429				13.5			19,363				61.7			1,795				4.4			1,912				21.1			66,499			16.4
	BIG		7,850				2.4			1,404				4.5			8,186				19.9			807				8.9			18,247			4.5
	Total net par outstanding (1)		$	322,123			100	%		$	31,359			100	%		$	41,171			100	%		$	9,076			100	%		$	403,729		100	%
	_____________________
	-1	Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.
	Financial Guaranty Portfolio by Internal Rating
	As of December 31, 2013
			Public Finance							Public Finance							Structured Finance							Structured Finance							Total
			U.S.							Non-U.S.							U.S							Non-U.S
	Rating		Net Par				%			Net Par				%			Net Par				%			Net Par				%			Net Par			%
	Category		Outstanding							Outstanding							Outstanding							Outstanding							Outstanding
			(dollars in millions)
	AAA		$	4,998			1.4	%		$	1,016			3	%		$	32,317			54.9	%		$	9,684			69.1	%		$	48,015		10.5	%
	AA		107,503				30.5			422				1.2			9,431				16			577				4.1			117,933			25.7
	A		192,841				54.8			9,453				27.9			2,580				4.4			742				5.3			205,616			44.8
	BBB		37,745				10.7			21,499				63.2			3,815				6.4			1,946				13.9			65,005			14.1
	BIG		9,094				2.6			1,608				4.7			10,764				18.3			1,072				7.6			22,538			4.9
	Total net par outstanding (1)		$	352,181			100	%		$	33,998			100	%		$	58,907			100	%		$	14,021			100	%		$	459,107		100	%
	_____________________
	-1	Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of December 31, 2013, which are primarily in the BIG category.
Financial Guaranty Portfolio by Asset Class	Financial Guaranty Portfolio
	by Sector
		Gross Par Outstanding								Ceded Par Outstanding								Net Par Outstanding
	Sector	As of December 31, 2014				As of December 31, 2013				As of December 31, 2014				As of December 31, 2013				As of December 31, 2014				As of December 31, 2013
		(dollars in millions)
	Public finance:
	U.S.:
	General obligation	$	144,714			$	160,751			$	4,438			$	5,474			$	140,276			$	155,277
	Tax backed	65,600				70,552				3,075				3,728				62,525				66,824
	Municipal utilities	53,471				57,893				1,381				1,569				52,090				56,324
	Transportation	28,914				32,514				1,091				1,684				27,823				30,830
	Healthcare	16,225				17,663				1,377				1,531				14,848				16,132
	Higher education	13,485				14,470				386				399				13,099				14,071
	Infrastructure finance	5,098				5,014				917				900				4,181				4,114
	Housing	2,880				3,518				101				132				2,779				3,386
	Investor-owned utilities	944				992				0				1				944				991
	Other public finance—U.S.	3,575				4,249				17				17				3,558				4,232
	Total public finance—U.S.	334,906				367,616				12,783				15,435				322,123				352,181
	Non-U.S.:
	Infrastructure finance	15,091				17,373				2,283				2,670				12,808				14,703
	Regulated utilities	14,582				15,502				3,668				4,297				10,914				11,205
	Pooled infrastructure	2,565				2,754				145				234				2,420				2,520
	Other public finance—non-U.S.	6,216				6,645				999				1,075				5,217				5,570
	Total public finance—non-U.S.	38,454				42,274				7,095				8,276				31,359				33,998
	Total public finance	373,360				409,890				19,878				23,711				353,482				386,179
	Structured finance:
	U.S.:
	Pooled corporate obligations	21,791				32,955				1,145				1,630				20,646				31,325
	RMBS	10,109				14,542				692				821				9,417				13,721
	Insurance securitizations	3,480				3,082				47				47				3,433				3,035
	Financial product	2,276				2,709				—				—				2,276				2,709
	Consumer receivables	2,157				2,257				58				59				2,099				2,198
	Commercial mortgage-backed securities ("CMBS") and other commercial real estate related exposures	1,979				3,990				22				38				1,957				3,952
	Commercial receivables	567				918				7				7				560				911
	Structured credit	71				71				2				2				69				69
	Other structured finance—U.S.	858				2,067				144				1,080				714				987
	Total structured finance—U.S.	43,288				62,591				2,117				3,684				41,171				58,907
	Non-U.S.:
	Pooled corporate obligations	7,439				12,232				835				1,174				6,604				11,058
	Commercial receivables	965				1,286				21				23				944				1,263
	RMBS	893				1,296				99				150				794				1,146
	Structured credit	9				197				—				21				9				176
	Other structured finance—non-U.S.	750				403				25				25				725				378
	Total structured finance—non-U.S.	10,056				15,414				980				1,393				9,076				14,021
	Total structured finance	53,344				78,005				3,097				5,077				50,247				72,928
	Total net par outstanding	$	426,704			$	487,895			$	22,975			$	28,788			$	403,729			$	459,107
Expected Amortization of Net Par Outstanding	Expected Amortization of
	Net Par Outstanding
	As of December 31, 2014
		Public Finance				Structured Finance				Total
		(in millions)
	0 to 5 years	$	98,431			$	36,482			$	134,913
	5 to 10 years	75,279				5,454				80,733
	10 to 15 years	67,354				2,874				70,228
	15 to 20 years	51,139				2,412				53,551
	20 years and above	61,279				3,025				64,304
	Total net par outstanding	$	353,482			$	50,247			$	403,729
Components of BIG Net Par Outstanding (Insurance and Credit Derivative Form)	Components of BIG Net Par Outstanding
	(Insurance and Credit Derivative Form)
	As of December 31, 2014
		BIG Net Par Outstanding																Net Par
		BIG 1				BIG 2				BIG 3				Total BIG				Outstanding
										(in millions)
	First lien U.S. RMBS:
	Prime first lien	$	68			$	33			$	252			$	353			$	471
	Alt-A first lien	585				531				725				1,841				2,532
	Option ARM	47				18				118				183				407
	Subprime	156				654				765				1,575				4,051
	Second lien U.S. RMBS:
	Closed-end second lien	—				19				115				134				218
	Home equity lines of credit (“HELOCs”)	1,012				36				509				1,557				1,738
	Total U.S. RMBS	1,868				1,291				2,484				5,643				9,417
	Trust preferred securities (“TruPS”)	997				—				336				1,333				4,326
	Other structured finance	1,021				240				756				2,017				36,504
	U.S. public finance	6,577				1,156				117				7,850				322,123
	Non-U.S. public finance	1,402				2				—				1,404				31,359
	Total	$	11,865			$	2,689			$	3,693			$	18,247			$	403,729
	Components of BIG Net Par Outstanding
	(Insurance and Credit Derivative Form)
	As of December 31, 2013
		BIG Net Par Outstanding																Net Par
		BIG 1				BIG 2				BIG 3				Total BIG				Outstanding
										(in millions)
	First lien U.S. RMBS:
	Prime first lien	$	52			$	321			$	30			$	403			$	541
	Alt-A first lien	656				1,137				935				2,728				3,590
	Option ARM	71				60				467				598				937
	Subprime	297				908				740				1,945				6,130
	Second lien U.S. RMBS:
	Closed-end second lien	8				20				118				146				244
	HELOCs	1,499				20				378				1,897				2,279
	Total U.S. RMBS	2,583				2,466				2,668				7,717				13,721
	TruPS	1,587				135				—				1,722				4,970
	Other structured finance	1,367				309				721				2,397				54,237
	U.S. public finance	8,205				440				449				9,094				352,181
	Non-U.S. public finance	1,009				599				—				1,608				33,998
	Total	$	14,751			$	3,949			$	3,838			$	22,538			$	459,107
BIG Net Par Outstanding and Number of Risks	BIG Net Par Outstanding
	and Number of Risks
	As of December 31, 2014
			Net Par Outstanding												Number of Risks(2)
	Description		Financial				Credit				Total				Financial			Credit			Total
			Guaranty				Derivative								Guaranty			Derivative
			Insurance(1)												Insurance(1)
			(dollars in millions)
	BIG:
	Category 1		$	10,195			$	1,670			$	11,865			164			18			182
	Category 2		2,135				554				2,689				75			14			89
	Category 3		2,892				801				3,693				119			24			143
	Total BIG		$	15,222			$	3,025			$	18,247			358			56			414
	BIG Net Par Outstanding
	and Number of Risks
	As of December 31, 2013
			Net Par Outstanding												Number of Risks(2)
	Description		Financial				Credit				Total				Financial			Credit			Total
			Guaranty				Derivative								Guaranty			Derivative
			Insurance(1)												Insurance(1)
			(dollars in millions)
	BIG:
	Category 1		$	12,391			$	2,360			$	14,751			185			25			210
	Category 2		2,323				1,626				3,949				80			21			101
	Category 3		3,031				807				3,838				119			27			146
	Total BIG		$	17,745			$	4,793			$	22,538			384			73			457
	_____________________
	(1)    Includes net par outstanding for FG VIEs.
	-2	A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments.
	Financial Guaranty Insurance
	BIG Transaction Loss Summary
	As of December 31, 2014
		BIG Categories
		BIG 1								BIG 2								BIG 3								Total				Effect of			Total
																										BIG, Net				Consolidating
		Gross				Ceded				Gross				Ceded				Gross				Ceded								FG VIEs
		(dollars in millions)
	Number of risks(1)	164				(59		)		75				(15		)		119				(38		)		358				—			358
	Remaining weighted-average contract period (in years)	9.9				7.4				10.1				8.9				9.6				6.9				10.3				—			10.3
	Outstanding exposure:
	Principal	$	12,358			$	(2,163	)		$	2,421			$	(286	)		$	3,067			$	(175	)		$	15,222			$	—		$	15,222
	Interest	6,350				(838		)		1,274				(121		)		1,034				(48		)		7,651				—			7,651
	Total(2)	$	18,708			$	(3,001	)		$	3,695			$	(407	)		$	4,101			$	(223	)		$	22,873			$	—		$	22,873
	Expected cash outflows (inflows)	$	1,762			$	(626	)		$	763			$	(77	)		$	1,716			$	(75	)		$	3,463			$	(345	)	$	3,118
	Potential recoveries
	Undiscounted R&W	(39		)		0				(48		)		2				(171		)		9				(247		)		8			(239		)
	Other(3)	(1,687		)		608				(206		)		5				(404		)		30				(1,654		)		177			(1,477		)
	Total potential recoveries	(1,726		)		608				(254		)		7				(575		)		39				(1,901		)		185			(1,716		)
	Subtotal	36				(18		)		509				(70		)		1,141				(36		)		1,562				(160		)	1,402
	Discount	3				0				(117		)		11				(353		)		9				(447		)		34			(413		)
	Present value of expected cash flows	$	39			$	(18	)		$	392			$	(59	)		$	788			$	(27	)		$	1,115			$	(126	)	$	989
	Deferred premium revenue	$	378			$	(70	)		$	119			$	(6	)		$	312			$	(33	)		$	700			$	(116	)	$	584
	Reserves (salvage)(4)	$	(42	)		$	(5	)		$	278			$	(53	)		$	482			$	(10	)		$	650			$	(79	)	$	571
	Financial Guaranty Insurance
	BIG Transaction Loss Summary
	As of December 31, 2013
		BIG Categories
		BIG 1								BIG 2								BIG 3								Total				Effect of			Total
																										BIG, Net				Consolidating
		Gross				Ceded				Gross				Ceded				Gross				Ceded								FG VIEs
		(dollars in millions)
	Number of risks(1)	185				(72		)		80				(24		)		119				(34		)		384				—			384
	Remaining weighted-average contract period (in years)	10.5				8.1				8.3				5.9				9.8				7.2				10.5				—			10.5
	Outstanding exposure:
Principal	$	15,132			$	(2,741	)		$	2,483			$	(160	)		$	3,189			$	(158	)		$	17,745			$	—		$	17,745
Interest	8,114				(1,144		)		1,181				(53		)		1,244				(52		)		9,290				—			9,290
Total(2)	$	23,246			$	(3,885	)		$	3,664			$	(213	)		$	4,433			$	(210	)		$	27,035			$	—		$	27,035
Expected cash outflows (inflows)	$	1,853			$	(528	)		$	1,038			$	(40	)		$	1,681			$	(62	)		$	3,942			$	(690	)	$	3,252
Potential recoveries
Undiscounted R&W	(105		)		1				(201		)		8				(356		)		13				(640		)		72			(568		)
Other(3)	(1,774		)		513				(470		)		19				(351		)		19				(2,044		)		507			(1,537		)
Total potential recoveries	(1,879		)		514				(671		)		27				(707		)		32				(2,684		)		579			(2,105		)
Subtotal	(26		)		(14		)		367				(13		)		974				(30		)		1,258				(111		)	1,147
Discount	13				—				(126		)		3				(352		)		5				(457		)		51			(406		)
Present value of expected cash flows	$	(13	)		$	(14	)		$	241			$	(10	)		$	622			$	(25	)		$	801			$	(60	)	$	741
Deferred premium revenue	$	517			$	(90	)		$	163			$	(7	)		$	303			$	(27	)		$	859			$	(178	)	$	681
Reserves (salvage)(4)	$	(114	)		$	1			$	117			$	(4	)		$	420			$	(13	)		$	407			$	(18	)	$	389
____________________
-1	A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments. The ceded number of risks represents the number of risks for which the Company ceded a portion of its exposure.
-2	Includes BIG amounts related to FG VIEs.
-3	Includes excess spread and draws on HELOCs.
-4	See table “Components of net reserves (salvage).”
Net Direct Economic Exposure to Selected European Countries	Net Direct Economic Exposure to Selected European Countries(1)
	As of December 31, 2014
		Hungary				Italy				Portugal				Spain				Total
		(in millions)
	Sovereign and sub-sovereign exposure:
	Non-infrastructure public finance(2)	$	—			$	878			$	91			$	239			$	1,208
	Infrastructure finance	313				13				11				135				472
	Total sovereign and sub-sovereign exposure	313				891				102				374				1,680
	Non-sovereign exposure:
	Regulated utilities	—				220				—				—				220
	RMBS	186				267				—				—				453
	Total non-sovereign exposure	186				487				—				—				673
	Total	$	499			$	1,378			$	102			$	374			$	2,353
	Total BIG (See Note 6)	$	424			$	—			$	102			$	374			$	900
	____________________
Schedule of Geographic Exposure of Net Par Outstanding	Geographic Distribution of
	Net Par Outstanding
	As of December 31, 2014
		Number of Risks			Net Par Outstanding				Percent of Total Net Par Outstanding
		(dollars in millions)
	U.S.:
	U.S. Public finance:
	California	1,465			$	50,668			12.6	%
	Pennsylvania	1,009			26,173				6.5
	New York	995			26,044				6.5
	Texas	1,239			25,449				6.3
	Illinois	830			22,825				5.7
	Florida	384			19,470				4.8
	New Jersey	602			13,558				3.4
	Michigan	668			12,739				3.2
	Georgia	192			8,217				2
	Ohio	507			7,818				1.9
	Other states and U.S. territories	4,174			109,162				27
	Total U.S. public finance	12,065			322,123				79.9
	U.S. Structured finance (multiple states)	839			41,171				10.2
	Total U.S.	12,904			363,294				90.1
	Non-U.S.:
	United Kingdom	114			19,856				4.9
	Australia	26			4,121				1
	Canada	10			3,526				0.9
	France	20			2,820				0.7
	Italy	9			1,501				0.4
	Other	78			8,611				2
	Total non-U.S.	257			40,435				9.9
	Total	13,161			$	403,729			100	%
Puerto Rico [Member]
Schedule of Insured Financial Obligations [Line Items]
BIG Net Par Outstanding and Number of Risks	Amortization Schedule of Puerto Rico BIG Net Par Outstanding
	and BIG Net Debt Service Outstanding
	As of December 31, 2014
		Scheduled BIG Net Par Amortization												Scheduled BIG Net Debt Service Amortization
		Subject to the Now Voided Recovery Act				Not Subject to the Now Voided Recovery Act				Total				Subject to the Now Voided Recovery Act				Not Subject to the Now Voided Recovery Act				Total
		(in millions)
	2015	$	126			$	205			$	331			$	249			$	319			$	568
	2016	84				183				267				199				287				486
	2017	41				166				207				153				262				415
	2018	48				109				157				158				195				353
	2019	61				126				187				168				207				375
	2020	73				182				255				176				258				434
	2021	51				58				109				151				124				275
	2022	42				67				109				140				129				269
	2023	102				40				142				198				99				297
	2024	82				78				160				174				136				310
	2025 - 2029	576				340				916				951				566				1,517
	2030 - 2034	440				387				827				696				541				1,237
	2035 - 2039	397				270				667				526				304				830
	2040 - 2044	78				12				90				147				13				160
	2045 - 2047	246				—				246				271				—				271
	Total	$	2,447			$	2,223			$	4,670			$	4,357			$	3,440			$	7,797
Gross Par and Gross Debt Service Outstanding	Puerto Rico
	Gross Par and Gross Debt Service Outstanding
		Gross Par Outstanding								Gross Debt Service Outstanding
		December 31,				December 31,				December 31,				December 31,
		2014				2013				2014				2013
		(in millions)
	Subject to the Now Voided Recovery Act (1)	$	3,058			$	3,279			$	5,326			$	5,748
	Not subject to the Now Voided Recovery Act	2,977				3,517				4,748				5,599
	Total	$	6,035			$	6,796			$	10,074			$	11,347
	____________________
	-1	On February 6, 2015, the U.S. District Court for the District of Puerto Rico ruled that the Recovery Act is preempted by the Federal Bankruptcy Code and is therefore void. On February 19, 2015, the Commonwealth appealed the ruling
Schedule of Geographic Exposure of Net Par Outstanding	The following table shows the Company’s exposure to general obligation bonds of Puerto Rico and various obligations of its related authorities and public corporations.
	Puerto Rico
	Net Par Outstanding
			As of						As of
			31-Dec-14						31-Dec-13
			Total				Internal Rating		Total				Internal Rating
			(in millions)
	Exposures subject to the Now Voided Recovery Act:
	PRHTA (Transportation revenue)		$	844			BB-		$	872			BB-
	PREPA		772				B-		860				BB-
	Puerto Rico Aqueduct and Sewer Authority		384				BB-		384				BB-
	PRHTA (Highway revenue)		273				BB		302				BB
	Puerto Rico Convention Center District Authority		174				BB-		185				BB-
	Puerto Rico Public Finance Corporation		—				—		44				B
	Total		2,447						2,647
	Exposures not subject to the Now Voided Recovery Act:
	Commonwealth of Puerto Rico - General Obligation Bonds		1,672				BB		1,885				BB
	Puerto Rico Municipal Finance Agency		399				BB-		450				BB-
	Puerto Rico Sales Tax Financing Corporation		269				BBB		268				A-
	Puerto Rico Public Buildings Authority		100				BB		139				BB
	GDB		33				BB		33				BB
	Puerto Rico Infrastructure Finance Authority		18				BB-		18				BB-
	University of Puerto Rico		1				BB-		1				BB-
	Total		2,492						2,794
	Total net exposure to Puerto Rico		$	4,939					$	5,441

Financial_Guaranty_Insurance_P1

Financial Guaranty Insurance Premiums (Tables)	12 Months Ended
	Dec. 31, 2014
Insurance [Abstract]
Net Earned Premiums	Net Earned Premiums
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Scheduled net earned premiums	$	415		$	470		$	581
	Acceleration of net earned premiums	136			263			249
	Accretion of discount on net premiums receivable	16			17			22
	Financial guaranty insurance net earned premiums	567			750			852
	Other	3			2			1
	Net earned premiums (1)	$	570		$	752		$	853
	___________________
	-1	Excludes $32 million, $60 million and $153 million for the year ended December 31, 2014, 2013 and 2012, respectively, related to consolidated FG VIEs.
Components of Unearned Premium Reserve	Components of
	Unearned Premium Reserve
		As of December 31, 2014									As of December 31, 2013
		Gross			Ceded			Net(1)			Gross			Ceded			Net(1)
		(in millions)
	Deferred premium revenue:
	Financial guaranty insurance	$	4,167		$	387		$	3,780		$	4,647		$	470		$	4,177
	Other	0			—			0			5			—			5
	Deferred premium revenue	$	4,167		$	387		$	3,780		$	4,652		$	470		$	4,182
	Contra-paid(2)	94			(6		)	100			(57		)	(18		)	(39		)
	Unearned premium reserve	$	4,261		$	381		$	3,880		$	4,595		$	452		$	4,143
	____________________
	-1	Excludes $125 million and $187 million deferred premium revenue and $42 million and $55 million of contra-paid related to FG VIEs as of December 31, 2014 and December 31, 2013, respectively.
	-2	See Note 7, "Financial Guaranty Insurance Losses– Insurance Contracts' Loss Information" for an explanation of "contra-paid".
Gross Premium Receivable, Net of Commissions on Assumed Business Roll Forward	Gross Premium Receivable,
	Net of Commissions on Assumed Business
	Roll Forward
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Beginning of period, December 31	$	876		$	1,005		$	1,003
	Gross premium written, net of commissions on assumed business	171			145			211
	Gross premiums received, net of commissions on assumed business	(230		)	(259		)	(294		)
	Adjustments:
	Changes in the expected term	(66		)	(28		)	44
	Accretion of discount, net of commissions on assumed business	10			20			36
	Foreign exchange translation	(31		)	(1		)	13
	Consolidation/deconsolidation of FG VIEs	(1		)	—			(5		)
	Other adjustments	—			(6		)	(3		)
	End of period, December 31 (1)	$	729		$	876		$	1,005
	____________________
	-1	Excludes $19 million, $21 million and $29 million as of December 31, 2014 , 2013 and 2012, respectively, related to consolidated FG VIEs.
Expected Collections of Gross Premiums Receivable, Net of Ceding Commissions (Undiscounted)	Expected Collections of
	Gross Premiums Receivable,
	Net of Commissions on Assumed Business
	(Undiscounted)
		As of December 31, 2014
		(in millions)
	2015 (January 1 – March 31)	$	31
	2015 (April 1 – June 30)	26
	2015 (July 1 – September 30)	20
	2015 (October 1 – December 31)	20
	2016	74
	2017	69
	2018	62
	2019	58
	2020-2024	242
	2025-2029	154
	2030-2034	106
	After 2034	102
	Total(1)	$	964
	____________________
	-1	Excludes expected cash collections on FG VIEs of $25 million.
Schedule of Net Earned Premiums	Scheduled Net Earned Premiums
		As of December 31, 2014
		(in millions)
	2015 (January 1 – March 31)	$	93
	2015 (April 1 – June 30)	91
	2015 (July 1 – September 30)	89
	2015 (October 1 – December 31)	86
	Subtotal 2015	359
	2016	332
	2017	295
	2018	269
	2019	246
	2020-2024	968
	2025-2029	615
	2030-2034	370
	After 2034	326
	Total present value basis(1)	3,780
	Discount	208
	Total future value	$	3,988
	____________________
	-1	Excludes scheduled net earned premiums on consolidated FG VIEs of $125 million.
Selected Information for Policies Paid in Installments	Selected Information for Policies Paid in Installments
		As of			As of
		31-Dec-14			31-Dec-13
		(dollars in millions)
	Premiums receivable, net of commission payable	$	729		$	876
	Gross deferred premium revenue	1,370			1,576
	Weighted-average risk-free rate used to discount premiums	3.5		%	3.4		%
	Weighted-average period of premiums receivable (in years)	9.4			9.4

Financial_Guaranty_Insurance_A1

Financial Guaranty Insurance Acquisition Costs (Tables)	12 Months Ended
	Dec. 31, 2014
Insurance [Abstract]
Rollforward of Deferred Acquisition Costs	Rollforward of
	Deferred Acquisition Costs
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Beginning of period	$	124		$	116		$	132
	Costs deferred during the period:
	Commissions on assumed and ceded business	7			9			(13		)
	Premium taxes	3			4			4
	Compensation and other acquisition costs	10			8			10
	Total	20			21			1
	Costs amortized during the period	(23		)	(13		)	(17		)
	End of period	$	121		$	124		$	116

Expected_Loss_to_be_Paid_Table

Expected Loss to be Paid (Tables)	12 Months Ended
	Dec. 31, 2014
Expected Losses [Abstract]
Net Expected Loss to be Paid Before Recoveries for Breaches of R&W Roll Forward by Sector	Net Expected Loss to be Paid
	Before Net Expected Recoveries for Breaches of R&W
	Roll Forward by Sector
	Year Ended December 31, 2014
		Net Expected				Economic Loss				(Paid)			Net Expected
		Loss to be				Development				Recovered			Loss to be
		Paid (Recovered) as of								Losses(1)			Paid (Recovered) as of
		December 31, 2013(2)											December 31, 2014(2)
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	25			$	(17	)		$	(2	)	$	6
	Alt-A first lien	578				(13		)		(155		)	410
	Option ARM	164				(45		)		(120		)	(1		)
	Subprime	422				43				(53		)	412
	Total first lien	1,189				(32		)		(330		)	827
	Second lien:
	Closed-end second lien	87				(3		)		9			93
	HELOCs	(71		)		35				17			(19		)
	Total second lien	16				32				26			74
	Total U.S. RMBS	1,205				0				(304		)	901
	TruPS	51				(28		)		—			23
	Other structured finance	120				96				2			218
	U.S. public finance	264				183				(144		)	303
	Non-U.S. public finance	57				(12		)		—			45
	Other insurance	(3		)		(1		)		—			(4		)
	Total	$	1,694			$	238			$	(446	)	$	1,486
	Net Expected Loss to be Paid
	Before Net Expected Recoveries for Breaches of R&W
	Roll Forward by Sector
	Year Ended December 31, 2013
		Net Expected				Economic Loss				(Paid)			Net Expected
		Loss to be				Development				Recovered			Loss to be
		Paid (Recovered) as of								Losses(1)			Paid (Recovered) as of
		December 31, 2012											December 31, 2013(2)
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	10			$	16			$	(1	)	$	25
	Alt-A first lien	693				(40		)		(75		)	578
	Option ARM	460				63				(359		)	164
	Subprime	351				101				(30		)	422
	Total first lien	1,514				140				(465		)	1,189
	Second lien:
	Closed-end second lien	99				(3		)		(9		)	87
	HELOCs	39				3				(113		)	(71		)
	Total second lien	138				0				(122		)	16
	Total U.S. RMBS	1,652				140				(587		)	1,205
	TruPS	27				7				17			51
	Other structured finance	312				(41		)		(151		)	120
	U.S. public finance	7				239				18			264
	Non-U.S. public finance	52				17				(12		)	57
	Other insurance	(3		)		(10		)		10			(3		)
	Total	$	2,047			$	352			$	(705	)	$	1,694
	____________________
	-1	Net of ceded paid losses, whether or not such amounts have been settled with reinsurers. Ceded paid losses are typically settled 45 days after the end of the reporting period. Such amounts are recorded in reinsurance recoverable on paid losses included in other assets. The Company paid $37 million and $54 million in LAE for the years ended December 31, 2014 and 2013, respectively.
	-2	Includes expected LAE to be paid of $16 million as of December 31, 2014 and $34 million as of December 31, 2013.
Net Expected Recoveries from Breaches of R&W Rollforward	Net Expected Recoveries from
	Breaches of R&W Rollforward
	Year Ended December 31, 2014
		Future Net				R&W Development				R&W (Recovered)			Future Net
		R&W Benefit as of				and Accretion of				During 2014			R&W Benefit as of
		December 31, 2013				Discount							December 31, 2014 (1)
						During 2014
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	4			$	(1	)		$	(1	)	$	2
	Alt-A first lien	274				131				(299		)	106
	Option ARM	173				14				(172		)	15
	Subprime	118				50				(59		)	109
	Total first lien	569				194				(531		)	232
	Second lien:
	Closed-end second lien	98				(6		)		(7		)	85
	HELOC	45				80				(125		)	—
	Total second lien	143				74				(132		)	85
	Total	$	712			$	268			$	(663	)	$	317
	Net Expected Recoveries from
	Breaches of R&W Rollforward
	Year Ended December 31, 2013
		Future Net				R&W Development				R&W (Recovered) During 2013			Future Net
		R&W Benefit as of				and Accretion of							R&W Benefit as of
		December 31, 2012				Discount							December 31, 2013
						During 2013
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	4			$	—			$	—		$	4
	Alt-A first lien	378				41				(145		)	274
	Option ARM	591				161				(579		)	173
	Subprime	109				9				—			118
	Total first lien	1,082				211				(724		)	569
	Second lien:
	Closed-end second lien	138				(9		)		(31		)	98
	HELOC	150				94				(199		)	45
	Total second lien	288				85				(230		)	143
	Total	$	1,370			$	296			$	(954	)	$	712
	____________________
	-1	See the section "Breaches of Representations and Warranties" below for eligible assets held in trust.
Net Expected Loss to be Paid After Net Expected Recoveries for Breaches of R&W Roll Forward	Net Expected Loss to be Paid
	After Net Expected Recoveries for Breaches of R&W
	Roll Forward by Sector
	Year Ended December 31, 2014
		Net Expected				Economic Loss				(Paid)			Net Expected
		Loss to be				Development				Recovered			Loss to be
		Paid (Recovered) as of								Losses(1)			Paid (Recovered) as of
		December 31, 2013											December 31, 2014
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	21			$	(16	)		$	(1	)	$	4
	Alt-A first lien	304				(144		)		144			304
	Option ARM	(9		)		(59		)		52			(16		)
	Subprime	304				(7		)		6			303
	Total first lien	620				(226		)		201			595
	Second lien:
	Closed-end second lien	(11		)		3				16			8
	HELOCs	(116		)		(45		)		142			(19		)
	Total second lien	(127		)		(42		)		158			(11		)
	Total U.S. RMBS	493				(268		)		359			584
	TruPS	51				(28		)		—			23
	Other structured finance	120				96				2			218
	U.S. public finance	264				183				(144		)	303
	Non-U.S. public finance	57				(12		)		—			45
	Other insurance	(3		)		(1		)		—			(4		)
	Total	$	982			$	(30	)		$	217		$	1,169
	Net Expected Loss to be Paid
	After Net Expected Recoveries for Breaches of R&W
	Roll Forward by Sector
	Year Ended December 31, 2013
		Net Expected				Economic Loss				(Paid)			Net Expected
		Loss to be				Development				Recovered			Loss to be
		Paid (Recovered) as of								Losses(1)			Paid (Recovered) as of
		December 31, 2012											December 31, 2013
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	6			$	16			$	(1	)	$	21
	Alt-A first lien	315				(81		)		70			304
	Option ARM	(131		)		(98		)		220			(9		)
	Subprime	242				92				(30		)	304
	Total first lien	432				(71		)		259			620
	Second lien:
	Closed-end second lien	(39		)		6				22			(11		)
	HELOCs	(111		)		(91		)		86			(116		)
	Total second lien	(150		)		(85		)		108			(127		)
	Total U.S. RMBS	282				(156		)		367			493
	TruPS	27				7				17			51
	Other structured finance	312				(41		)		(151		)	120
	U.S. public finance	7				239				18			264
	Non-U.S. public finance	52				17				(12		)	57
	Other insurance	(3		)		(10		)		10			(3		)
	Total	$	677			$	56			$	249		$	982
	____________________
	-1	Net of ceded paid losses, whether or not such amounts have been settled with reinsurers. Ceded paid losses and recoveries are typically settled 45 days after the end of the reporting period. Such amounts are recorded in reinsurance recoverable on paid losses included in other assets.
Net Expected Loss to be Paid By Accounting Model	Net Expected Loss to be Paid (Recovered)
	By Accounting Model
	As of December 31, 2014
		Financial				FG VIEs(1)				Credit			Total
		Guaranty								Derivatives(2)
		Insurance
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	2			$	—			$	2		$	4
	Alt-A first lien	288				17				(1		)	304
	Option ARM	(15		)		—				(1		)	(16		)
	Subprime	163				71				69			303
	Total first lien	438				88				69			595
	Second lien:
	Closed-end second lien	(27		)		31				4			8
	HELOCs	(26		)		7				—			(19		)
	Total second lien	(53		)		38				4			(11		)
	Total U.S. RMBS	385				126				73			584
	TruPS	1				—				22			23
	Other structured finance	255				—				(37		)	218
	U.S. public finance	303				—				—			303
	Non-U.S. public finance	45				—				—			45
	Subtotal	$	989			$	126			$	58		1,173
	Other												(4		)
	Total												$	1,169
	Net Expected Loss to be Paid (Recovered)
	By Accounting Model
	As of December 31, 2013
		Financial				FG VIEs(1)				Credit			Total
		Guaranty								Derivatives(2)
		Insurance
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	3			$	—			$	18		$	21
	Alt-A first lien	199				31				74			304
	Option ARM	(18		)		(2		)		11			(9		)
	Subprime	149				81				74			304
	Total first lien	333				110				177			620
	Second lien:
	Closed-end second lien	(34		)		25				(2		)	(11		)
	HELOCs	(41		)		(75		)		—			(116		)
	Total second lien	(75		)		(50		)		(2		)	(127		)
	Total U.S. RMBS	258				60				175			493
	TruPS	3				—				48			51
	Other structured finance	161				—				(41		)	120
	U.S. public finance	264				—				—			264
	Non-U.S. public finance	55				—				2			57
	Subtotal	$	741			$	60			$	184		985
	Other												(3		)
	Total												$	982
	___________________
	(1)    Refer to Note 10, Consolidated Variable Interest Entities.
	(2)    Refer to Note 9, Financial Guaranty Contracts Accounted for as Credit Derivatives.
Schedule of Net Economic Loss Development	Net Economic Loss Development (Benefit)
	By Accounting Model
	Year Ended December 31, 2014
		Financial				FG VIEs(1)				Credit			Total
		Guaranty								Derivatives(2)
		Insurance
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	—			$	—			$	(16	)	$	(16	)
	Alt-A first lien	(87		)		(13		)		(44		)	(144		)
	Option ARM	(48		)		1				(12		)	(59		)
	Subprime	(15		)		6				2			(7		)
	Total first lien	(150		)		(6		)		(70		)	(226		)
	Second lien:
	Closed-end second lien	(2		)		8				(3		)	3
	HELOCs	(128		)		83				—			(45		)
	Total second lien	(130		)		91				(3		)	(42		)
	Total U.S. RMBS	(280		)		85				(73		)	(268		)
	TruPS	(2		)		—				(26		)	(28		)
	Other structured finance	97				—				(1		)	96
	U.S. public finance	183				—				—			183
	Non-U.S. public finance	(10		)		—				(2		)	(12		)
	Subtotal	$	(12	)		$	85			$	(102	)	(29		)
	Other												(1		)
	Total												$	(30	)
	Net Economic Loss Development (Benefit)
	By Accounting Model
	Year Ended December 31, 2013
		Financial				FG VIEs(1)				Credit			Total
		Guaranty								Derivatives(2)
		Insurance
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	(1	)		$	—			$	17		$	16
	Alt-A first lien	(54		)		5				(32		)	(81		)
	Option ARM	(62		)		(36		)		—			(98		)
	Subprime	48				32				12			92
	Total first lien	(69		)		1				(3		)	(71		)
	Second lien:
	Closed-end second lien	30				(34		)		10			6
	HELOCs	(91		)		(1		)		1			(91		)
	Total second lien	(61		)		(35		)		11			(85		)
	Total U.S. RMBS	(130		)		(34		)		8			(156		)
	TruPS	—				—				7			7
	Other structured finance	(36		)		—				(5		)	(41		)
	U.S. public finance	239				—				—			239
	Non-U.S. public finance	16				—				1			17
	Subtotal	$	89			$	(34	)		$	11		66
	Other												(10		)
	Total												$	56
	___________________
	(1)    Refer to Note 10, Consolidated Variable Interest Entities.
	(2)    Refer to Note 9, Financial Guaranty Contracts Accounted for as Credit Derivatives.
Liquidation Rates and Key Assumptions in Base Case Expected Loss Estimates First Lien RMBS	First Lien Liquidation Rates
		December 31, 2014		December 31, 2013		December 31, 2012
	Current Loans Modified in Previous 12 Months
	Alt A and Prime	25%		35%		N/A
	Option ARM	25		35		N/A
	Subprime	25		35		N/A
	Current Loans Delinquent in the Previous 12 Months
	Alt A and Prime	25		N/A		N/A
	Option ARM	25		N/A		N/A
	Subprime	25		N/A		N/A
	30 – 59 Days Delinquent
	Alt A and Prime	35		50		35%
	Option ARM	40		50		50
	Subprime	35		45		30
	60 – 89 Days Delinquent
	Alt A and Prime	50		60		55
	Option ARM	55		65		65
	Subprime	40		50		45
	90+ Days Delinquent
	Alt A and Prime	60		75		65
	Option ARM	65		70		75
	Subprime	55		60		60
	Bankruptcy
	Alt A and Prime	45		60		55
	Option ARM	50		60		70
	Subprime	40		55		50
	Foreclosure
	Alt A and Prime	75		85		85
	Option ARM	80		80		85
	Subprime	70		70		80
	Real Estate Owned
	All	100		100		100
	Key Assumptions in Base Case Expected Loss Estimates
	First Lien RMBS(1)
		As of							As of						As of
		31-Dec-14							31-Dec-13						31-Dec-12
		Range					Weighted Average		Range				Weighted Average		Range				Weighted Average
	Alt-A First Lien
	Plateau CDR	2	%	–	13.40%		7.30%		2.8	%	–	18.40%	9.70%		3.8	%	–	23.20%	13.30%
	Intermediate CDR	0.4	%	–	2.70%		1.50%		0.6	%	–	3.70%	1.90%		0.8	%	–	4.60%	2.70%
	Period until intermediate CDR	48 months							48 months						36 months
	Final CDR	0.1	%	–	0.70%		0.30%		0.1	%	–	0.90%	0.50%		0.2	%	–	1.20%	0.60%
	Initial loss severity:
	2005 and prior	60%							65%						65%
	2006	70%							65%						65%
	2007	65%							65%						65%
	Initial CPR	1.7	%	–	21.00%		7.70%		0	%	–	34.20%	9.70%		0	%	–	39.40%	7.40%
	Final CPR(2)	15%							15%						15%
	Option ARM
	Plateau CDR	4.3	%	–	14.20%		10.60%		4.9	%	–	16.80%	11.90%		7	%	–	26.10%	18.40%
	Intermediate CDR	0.9	%	–	2.80%		2.10%		1	%	–	3.40%	2.40%		1.4	%	–	5.20%	3.70%
	Period until intermediate CDR	48 months							48 months						36 months
	Final CDR	0.2	%	–	0.70%		0.50%		0.2	%	–	0.80%	0.50%		0.4	%	–	1.30%	0.80%
	Initial loss severity:
	2005 and prior	60%							65%						65%
	2006	70%							65%						65%
	2007	65%							65%						65%
	Initial CPR	1.1	%	–	11.80%		4.90%		0.4	%	–	13.10%	4.70%		0	%	–	10.70%	4.00%
	Final CPR(2)	15%							15%						15%
	Subprime
	Plateau CDR	4.9	%	–	15.00%		10.60%		5.6	%	–	16.20%	11.80%		7.3	%	–	26.20%	17.30%
	Intermediate CDR	1	%	–	3.00%		2.10%		1.1	%	–	3.20%	2.40%		1.5	%	–	5.20%	3.50%
	Period until intermediate CDR	48 months							48 months						36 months
	Final CDR	0.2	%	–	0.70%		0.40%		0.3	%	–	0.80%	0.40%		0.4	%	–	1.30%	0.60%
Initial loss severity:
2005 and prior	75%							90%						90%
2006	90%							90%						90%
2007	90%							90%						90%
Initial CPR	0	%	–	10.50%		6.10%		0	%	–	15.70%	4.10%		0	%	–	17.60%	3.60%
Final CPR(2)	15%							15%						15%
____________________
(1)                                Represents variables for most heavily weighted scenario (the “base case”).
(2)	For transactions where the initial CPR is higher than the final CPR, the initial CPR is held constant and the final CPR is not used.
Key Assumptions in Base Case Expected Loss Estimates Second Lien RMBS	Key Assumptions in Base Case Expected Loss Estimates
	Second Lien RMBS(1)
	HELOC key assumptions	As of							As of						As of
		31-Dec-14							31-Dec-13						31-Dec-12
		Range					Weighted Average		Range				Weighted Average		Range				Weighted Average
	Plateau CDR	2.8	%	–	6.80%		4.10%		2.3	%	–	7.70%	4.90%		3.8	%	–	15.90%	8.80%
	Final CDR trended down to	0.5	%	–	3.20%		1.20%		0.4	%	–	3.20%	1.10%		0.4	%	–	3.20%	1.20%
	Period until final CDR	34 months							34 months						36 months
	Initial CPR	6.9	%	–	21.80%		11.00%		2.7	%	–	21.50%	9.90%		2.9	%	–	15.40%	6.60%
	Final CPR(2)	15	%	–	21.80%		15.50%		10%						10%
	Loss severity	90	%	–	98%		90.40%		98%						98%
	Closed-end second lien key assumptions	As of							As of						As of
		31-Dec-14							31-Dec-13						31-Dec-12
		Range					Weighted Average		Range				Weighted Average		Range				Weighted Average
	Plateau CDR	5.5	%	–	12.50%		7.20%		7.3	%	–	15.10%	8.50%		7.3	%	–	20.70%	12.70%
	Final CDR trended down to	3.5	%	–	9.10%		4.90%		3.5	%	–	9.10%	5.00%		3.5	%	–	9.10%	4.90%
	Period until final CDR	34 months							34 months						36 months
	Initial CPR	2.8	%	–	13.90%		9.90%		3.1	%	–	12.00%	7.10%		1.9	%	–	12.50%	4.00%
	Final CPR(2)	15%							10%						10%
	Loss severity	98%							98%						98%
	____________________
	-1	Represents variables for most heavily weighted scenario (the “base case”).
	(2)	For transactions where the initial CPR is higher than the final CPR, the initial CPR is held constant and the final CPR is not used.
Components of Development and Accretion Amounts of Estimated Recoveries	The following table provides a breakdown of the development and accretion amount in the roll forward of estimated recoveries associated with claims for breaches of R&W.
	Components of R&W Development
		Year Ended December 31,
		2014				2013
		(in millions)
	Inclusion or removal of deals with breaches of R&W during period	$	—			$	6
	Change in recovery assumptions as the result of recovery success	31				(6		)
	Estimated increase (decrease) in defaults that will result in additional (lower) breaches	(37		)		(8		)
	Settlements and anticipated settlements	263				289
	Accretion of discount on balance	11				15
	Total	$	268			$	296

Financial_Guaranty_Insurance_L1

Financial Guaranty Insurance Losses (Tables)	12 Months Ended
	Dec. 31, 2014
Insurance [Abstract]
Loss and LAE Reserve and Salvage and Subrogation Recoverable Net of Reinsurance Insurance Contracts	Loss and LAE Reserve and Salvage and Subrogation Recoverable
	Net of Reinsurance
	Insurance Contracts
		As of December 31, 2014									As of December 31, 2013
		Loss and			Salvage and			Net Reserve (Recoverable)			Loss and			Salvage and				Net Reserve (Recoverable)
		LAE			Subrogation						LAE			Subrogation
		Reserve, net			Recoverable, net						Reserve, net			Recoverable, net
		(in millions)
	U.S. RMBS:
	First lien:
	Prime first lien	$	2		$	—		$	2		$	3		$	—			$	3
	Alt-A first lien	87			—			87			108			—				108
	Option ARM	28			40			(12		)	22			47				(25		)
	Subprime	166			8			158			143			2				141
	First lien	283			48			235			276			49				227
	Second lien:
	Closed-end second lien	4			39			(35		)	5			45				(40		)
	HELOC	3			39			(36		)	5			127				(122		)
	Second lien	7			78			(71		)	10			172				(162		)
	Total U.S. RMBS	290			126			164			286			221				65
	TruPS	0			—			0			2			—				2
	Other structured finance	236			2			234			145			6				139
	U.S. public finance	243			8			235			189			8				181
	Non-U.S. public finance	30			—			30			35			—				35
	Financial guaranty	799			136			663			657			235				422
	Other recoverables	—			13			(13		)	—			15				(15		)
	Subtotal	799			149			650			657			250				407
	Effect of consolidating FG VIEs	(80		)	(1		)	(79		)	(103		)	(85		)		(18		)
	Subtotal	719			148			571			554			165				389
	Other	2			6			(4		)	2			5				(3		)
	Total (1)	$	721		$	154		$	567		$	556		$	170			$	386
	____________________
	(1)                                 See “Components of Net Reserves (Salvage)” table for loss and LAE reserve and salvage and subrogation recoverable components.
Components of Net Reserves (Salvage) Insurance Contracts	Components of Net Reserves (Salvage)
	Insurance Contracts
		As of			As of
		31-Dec-14			31-Dec-13
		(in millions)
	Loss and LAE reserve	$	799		$	592
	Reinsurance recoverable on unpaid losses	(78		)	(36		)
	Loss and LAE reserve, net	721			556
	Salvage and subrogation recoverable	(151		)	(174		)
	Salvage and subrogation payable(1)	10			19
	Other recoverables(2)	(13		)	(15		)
	Salvage and subrogation recoverable, net and other recoverable	(154		)	(170		)
	Subtotal	567			386
	Less: other (non-financial guaranty business)	(4		)	(3		)
	Net reserves (salvage) - financial guaranty	$	571		$	389
	____________________
	(1)          Recorded as a component of reinsurance balances payable.
	(2)     R&W recoverables recorded in other assets on the consolidated balance sheet.
Balance Sheet Classification of Net Expected Recoveries for Breaches of R&W Insurance Contracts	Balance Sheet Classification of
	Net Expected Recoveries for Breaches of R&W
	Insurance Contracts
		As of December 31, 2014									As of December 31, 2013
		For all			Effect of			Reported on			For all			Effect of				Reported on
		Financial			Consolidating			Balance Sheet(1)			Financial			Consolidating				Balance Sheet(1)
		Guaranty			FG VIEs						Guaranty			FG VIEs
		Insurance									Insurance
		Contracts									Contracts
		(in millions)
	Salvage and subrogation recoverable, net	$	20		$	—		$	20		$	122		$	(49	)		$	73
	Loss and LAE reserve, net	185			(8		)	177			363			(24		)		339
	____________________
	-1	The remaining benefit for R&W is either recorded at fair value in FG VIE assets, or not recorded on the balance sheet until the total loss, net of R&W, exceeds unearned premium reserve.
Reconciliation of Net Expected Loss to be Paid and Net Expected Loss to be Expensed Financial Guaranty Insurance Contracts	Reconciliation of Net Expected Loss to be Paid and
	Net Expected Loss to be Expensed
	Financial Guaranty Insurance Contracts
		As of December 31, 2014
		(in millions)
	Net expected loss to be paid	$	1,115
	Less: net expected loss to be paid for FG VIEs	126
	Total	989
	Contra-paid, net	(100		)
	Salvage and subrogation recoverable, net of reinsurance	135
	Loss and LAE reserve, net of reinsurance	(719		)
	Other recoveries (1)	13
	Net expected loss to be expensed (present value)(2)	$	318
	____________________
	-1	R&W recoverables recorded in other assets on the consolidated balance sheet.
	-2	Excludes $89 million as of December 31, 2014 related to consolidated FG VIEs.
Net Expected Loss to be Expensed Insurance Contracts	Net Expected Loss to be Expensed
	Financial Guaranty Insurance Contracts
		As of December 31, 2014
		(in millions)
	2015 (January 1 – March 31)	$	8
	2015 (April 1 – June 30)	8
	2015 (July 1 – September 30)	8
	2015 (October 1 – December 31)	9
	Subtotal 2015	33
	2016	34
	2017	27
	2018	24
	2019	22
	2020-2024	79
	2025-2029	46
	2030-2034	32
	After 2034	21
	Net expected loss to be expensed	318
	Discount	413
	Total future value	$	731
Loss and LAE Reported on the Consolidated Statements of Operations	Loss and LAE
	Reported on the
	Consolidated Statements of Operations
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Structured Finance:
	U.S. RMBS:
	First lien:
	Prime first lien	$	(1	)	$	1		$	2
	Alt-A first lien	(66		)	(2		)	51
	Option ARM	(37		)	(48		)	137
	Subprime	8			80			38
	First lien	(96		)	31			228
	Second lien:
	Closed-end second lien	(2		)	18			31
	HELOC	(31		)	(53		)	49
	Second lien	(33		)	(35		)	80
	Total U.S. RMBS	(129		)	(4		)	308
	TruPS	(1		)	(1		)	(10		)
	Other structured finance	96			(34		)	3
	Structured finance	(34		)	(39		)	301
	Public Finance:
	U.S. public finance	192			198			51
	Non-U.S. public finance	(1		)	16			234
	Public finance	191			214			285
	Subtotal	157			175			586
	Other	(1		)	—			(17		)
	Loss and LAE on insurance contracts before FG VIE consolidation	156			175			569
	Effect of consolidating FG VIEs	(30		)	(21		)	(65		)
	Loss and LAE	$	126		$	154		$	504
Financial Guaranty Insurance BIG Transaction Loss Summary	BIG Net Par Outstanding
	and Number of Risks
	As of December 31, 2014
			Net Par Outstanding									Number of Risks(2)
	Description		Financial			Credit			Total			Financial		Credit			Total
			Guaranty			Derivative						Guaranty		Derivative
			Insurance(1)									Insurance(1)
			(dollars in millions)
	BIG:
	Category 1		$	10,195		$	1,670		$	11,865		164		18			182
	Category 2		2,135			554			2,689			75		14			89
	Category 3		2,892			801			3,693			119		24			143
	Total BIG		$	15,222		$	3,025		$	18,247		358		56			414
	BIG Net Par Outstanding
	and Number of Risks
	As of December 31, 2013
			Net Par Outstanding									Number of Risks(2)
	Description		Financial			Credit			Total			Financial		Credit			Total
			Guaranty			Derivative						Guaranty		Derivative
			Insurance(1)									Insurance(1)
			(dollars in millions)
	BIG:
	Category 1		$	12,391		$	2,360		$	14,751		185		25			210
	Category 2		2,323			1,626			3,949			80		21			101
	Category 3		3,031			807			3,838			119		27			146
	Total BIG		$	17,745		$	4,793		$	22,538		384		73			457
	_____________________
	(1)    Includes net par outstanding for FG VIEs.
	-2	A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments.
	Financial Guaranty Insurance
	BIG Transaction Loss Summary
	As of December 31, 2014
		BIG Categories
		BIG 1						BIG 2						BIG 3							Total			Effect of			Total
																					BIG, Net			Consolidating
		Gross			Ceded			Gross			Ceded			Gross				Ceded						FG VIEs
		(dollars in millions)
	Number of risks(1)	164			(59		)	75			(15		)	119				(38		)	358			—			358
	Remaining weighted-average contract period (in years)	9.9			7.4			10.1			8.9			9.6				6.9			10.3			—			10.3
	Outstanding exposure:
	Principal	$	12,358		$	(2,163	)	$	2,421		$	(286	)	$	3,067			$	(175	)	$	15,222		$	—		$	15,222
	Interest	6,350			(838		)	1,274			(121		)	1,034				(48		)	7,651			—			7,651
	Total(2)	$	18,708		$	(3,001	)	$	3,695		$	(407	)	$	4,101			$	(223	)	$	22,873		$	—		$	22,873
	Expected cash outflows (inflows)	$	1,762		$	(626	)	$	763		$	(77	)	$	1,716			$	(75	)	$	3,463		$	(345	)	$	3,118
	Potential recoveries
	Undiscounted R&W	(39		)	0			(48		)	2			(171		)		9			(247		)	8			(239		)
	Other(3)	(1,687		)	608			(206		)	5			(404		)		30			(1,654		)	177			(1,477		)
	Total potential recoveries	(1,726		)	608			(254		)	7			(575		)		39			(1,901		)	185			(1,716		)
	Subtotal	36			(18		)	509			(70		)	1,141				(36		)	1,562			(160		)	1,402
	Discount	3			0			(117		)	11			(353		)		9			(447		)	34			(413		)
	Present value of expected cash flows	$	39		$	(18	)	$	392		$	(59	)	$	788			$	(27	)	$	1,115		$	(126	)	$	989
	Deferred premium revenue	$	378		$	(70	)	$	119		$	(6	)	$	312			$	(33	)	$	700		$	(116	)	$	584
	Reserves (salvage)(4)	$	(42	)	$	(5	)	$	278		$	(53	)	$	482			$	(10	)	$	650		$	(79	)	$	571
	Financial Guaranty Insurance
	BIG Transaction Loss Summary
	As of December 31, 2013
		BIG Categories
		BIG 1						BIG 2						BIG 3							Total			Effect of			Total
																					BIG, Net			Consolidating
		Gross			Ceded			Gross			Ceded			Gross				Ceded						FG VIEs
		(dollars in millions)
	Number of risks(1)	185			(72		)	80			(24		)	119				(34		)	384			—			384
	Remaining weighted-average contract period (in years)	10.5			8.1			8.3			5.9			9.8				7.2			10.5			—			10.5
	Outstanding exposure:
Principal	$	15,132		$	(2,741	)	$	2,483		$	(160	)	$	3,189			$	(158	)	$	17,745		$	—		$	17,745
Interest	8,114			(1,144		)	1,181			(53		)	1,244				(52		)	9,290			—			9,290
Total(2)	$	23,246		$	(3,885	)	$	3,664		$	(213	)	$	4,433			$	(210	)	$	27,035		$	—		$	27,035
Expected cash outflows (inflows)	$	1,853		$	(528	)	$	1,038		$	(40	)	$	1,681			$	(62	)	$	3,942		$	(690	)	$	3,252
Potential recoveries
Undiscounted R&W	(105		)	1			(201		)	8			(356		)		13			(640		)	72			(568		)
Other(3)	(1,774		)	513			(470		)	19			(351		)		19			(2,044		)	507			(1,537		)
Total potential recoveries	(1,879		)	514			(671		)	27			(707		)		32			(2,684		)	579			(2,105		)
Subtotal	(26		)	(14		)	367			(13		)	974				(30		)	1,258			(111		)	1,147
Discount	13			—			(126		)	3			(352		)		5			(457		)	51			(406		)
Present value of expected cash flows	$	(13	)	$	(14	)	$	241		$	(10	)	$	622			$	(25	)	$	801		$	(60	)	$	741
Deferred premium revenue	$	517		$	(90	)	$	163		$	(7	)	$	303			$	(27	)	$	859		$	(178	)	$	681
Reserves (salvage)(4)	$	(114	)	$	1		$	117		$	(4	)	$	420			$	(13	)	$	407		$	(18	)	$	389
____________________
-1	A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments. The ceded number of risks represents the number of risks for which the Company ceded a portion of its exposure.
-2	Includes BIG amounts related to FG VIEs.
-3	Includes excess spread and draws on HELOCs.
-4	See table “Components of net reserves (salvage).”

Fair_Value_Measurement_Tables

Fair Value Measurement (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Information by Credit Spread Type	Information by Credit Spread Type (1)
		As of			As of
		31-Dec-14			31-Dec-13
	Based on actual collateral specific spreads	9	%		6	%
	Based on market indices	82	%		88	%
	Provided by the CDS counterparty	9	%		6	%
	Total	100	%		100	%
	____________________
	(1)    Based on par.
Schedule of example effects of change in gross spreads, company's own credit spread and cost to buy protection on the on the Company affect the amount of premium the company can demand for credit protection	Following is an example of how changes in gross spreads, the Company’s own credit spread and the cost to buy protection on the Company affect the amount of premium the Company can demand for its credit protection. The assumptions used in these examples are hypothetical amounts. Scenario 1 represents the market conditions in effect on the transaction date and Scenario 2 represents market conditions at a subsequent reporting date.
		Scenario 1						Scenario 2
		bps			% of Total			bps			% of Total
	Original gross spread/cash bond price (in bps)	185						500
	Bank profit (in bps)	115			62	%		50			10	%
	Hedge cost (in bps)	30			16	%		440			88	%
	The premium the Company receives per annum (in bps)	40			22	%		10			2	%
Fair Value Hierarchy of Financial Instruments Carried at Fair Value	Fair Value Hierarchy of Financial Instruments Carried at Fair Value
	As of December 31, 2014
						Fair Value Hierarchy
		Fair Value				Level 1				Level 2				Level 3
		(in millions)
	Assets:
	Investment portfolio, available-for-sale:
	Fixed-maturity securities
	Obligations of state and political subdivisions	$	5,795			$	—			$	5,757			$	38
	U.S. government and agencies	665				—				665				—
	Corporate securities	1,368				—				1,289				79
	Mortgage-backed securities:
	RMBS	1,285				—				860				425
	CMBS	659				—				659				—
	Asset-backed securities	417				—				189				228
	Foreign government securities	302				—				302				—
	Total fixed-maturity securities	10,491				—				9,721				770
	Short-term investments	767				359				408				—
	Other invested assets (1)	100				—				17				83
	Credit derivative assets	68				—				—				68
	FG VIEs’ assets, at fair value (2)	1,398				—				—				1,398
	Other assets	78				26				17				35
	Total assets carried at fair value	$	12,902			$	385			$	10,163			$	2,354
	Liabilities:
	Credit derivative liabilities	$	963			$	—			$	—			$	963
	FG VIEs’ liabilities with recourse, at fair value	1,277				—				—				1,277
	FG VIEs’ liabilities without recourse, at fair value	142				—				—				142
	Total liabilities carried at fair value	$	2,382			$	—			$	—			$	2,382
	Fair Value Hierarchy of Financial Instruments Carried at Fair Value
	As of December 31, 2013
						Fair Value Hierarchy
		Fair Value				Level 1				Level 2				Level 3
		(in millions)
	Assets:
	Investment portfolio, available-for-sale:
	Fixed-maturity securities
	Obligations of state and political subdivisions	$	5,079			$	—			$	5,043			$	36
	U.S. government and agencies	700				—				700				—
	Corporate securities	1,340				—				1,204				136
	Mortgage-backed securities:
	RMBS	1,122				—				832				290
	CMBS	549				—				549				—
	Asset-backed securities	608				—				340				268
	Foreign government securities	313				—				313				—
	Total fixed-maturity securities	9,711				—				8,981				730
	Short-term investments	904				506				398				—
	Other invested assets(1)	127				—				119				8
	Credit derivative assets	94				—				—				94
	FG VIEs’ assets, at fair value	2,565				—				—				2,565
	Other assets	84				27				11				46
	Total assets carried at fair value	$	13,485			$	533			$	9,509			$	3,443
	Liabilities:
	Credit derivative liabilities	$	1,787			$	—			$	—			$	1,787
	FG VIEs’ liabilities with recourse, at fair value	1,790				—				—				1,790
	FG VIEs’ liabilities without recourse, at fair value	1,081				—				—				1,081
	Total liabilities carried at fair value	$	4,658			$	—			$	—			$	4,658
	____________________
	-1	Includes Level 3 mortgage loans that are recorded at fair value on a non-recurring basis.
	-2	Exclude restricted cash.
Fair Value Assets Measured on Recurring Basis	Fair Value Level 3 Rollforward
	Recurring Basis
	Year Ended December 31, 2014
		Fixed-Maturity Securities
		Obligations					Corporate Securities					RMBS					Asset-					Other				FG VIEs’					Other					Credit					FG VIEs' Liabilities					FG VIEs’ Liabilities
		of State and															Backed					Invested				Assets at					Assets					Derivative					with					without
		Political															Securities					Assets				Fair										Asset					Recourse,					Recourse,
		Subdivisions																								Value										(Liability),					at Fair					at Fair
																																				net(5)					Value					Value
		(in millions)
	Fair value as of December 31, 2013	$	36				$	136				$	290				$	268				$	2			$	2,565				$	46				$	(1,693	)			$	(1,790	)			$	(1,081	)
	Total pretax realized and unrealized gains/(losses) recorded in:(1)
	Net income (loss)	4			(2	)	(46		)	(2	)	21			(2	)	17			(2	)	—				164			(3	)	(11		)	(4	)	823			(6	)	94			(3	)	(43		)	(3	)
	Other comprehensive income (loss)	(1		)			(6		)			24					5					6				—					—					—					—					—
	Purchases	—					—					263					—					70				—					—					—					—					—
	Settlements	(1		)			(5		)			(59		)			(62		)			0				(408		)			—					(25		)			374					22
	FG VIE consolidations	—					—					(127		)			—					—				206					—					—					(189		)			(42		)
	FG VIE deconsolidations	—					—					13					—					—				(1,129		)			—					—					234					1,002
	Fair value as of December 31, 2014	$	38				$	79				$	425				$	228				$	78			$	1,398				$	35				$	(895	)			$	(1,277	)			$	(142	)
	Change in unrealized gains/(losses) related to financial instruments held as of December 31, 2014	$	(1	)			$	(6	)			$	21				$	4				$	6			$	141				$	(11	)			$	254				$	(22	)			$	3
	Fair Value Level 3 Rollforward
	Recurring Basis
	Year Ended December 31, 2013
		Fixed-Maturity Securities
		Obligations of state and political subdivisions					Corporate Securities					RMBS					Asset Backed Securities					Other					FG VIEs’					Other					Credit					FG VIEs’ Liabilities					FG VIEs’ Liabilities
																						Invested					Assets at					Assets					Derivative					with					without
																						Assets					Fair										Asset					Recourse,					Recourse,
																											Value										(Liability),					at Fair					at Fair
																																					net(5)					Value					Value
		(in millions)
	Fair value as of December 31, 2012	$	35				$	—				$	219				$	306				$	1				$	2,688				$	36				$	(1,793	)			$	(2,090	)			$	(1,051	)
	Total pretax realized and unrealized gains/(losses) recorded in:(1)
	Net income (loss)	(8		)	(2	)	4			(2	)	13			(2	)	67			(2	)	(1		)	(7	)	686			(3	)	10			(4	)	65			(6	)	(166		)	(3	)	(225		)	(3	)
	Other comprehensive income (loss)	13					5					26					(43		)			2					—					—					—					—					—
	Purchases	—					130			(8	)	86					80					2			(8	)	—					—					—					—					—
	Settlements	(4		)			(3		)			(54		)			(142		)			(2		)			(663		)			—					35					343					168
	FG VIE consolidations	—					—					—					—					—					48					—					—					(12		)			(37		)
	FG VIE deconsolidations	—					—					—					—					—					(194		)			—					—					135					64
	Fair value as of December 31, 2013	$	36				$	136				$	290				$	268				$	2				$	2,565				$	46				$	(1,693	)			$	(1,790	)			$	(1,081	)
	Change in unrealized gains/(losses) related to financial instruments held as of December 31, 2013	$	14				$	5				$	27				$	(20	)			$	2				$	623				$	10				$	(139	)			$	(169	)			$	(326	)
	___________________
	-1	Realized and unrealized gains (losses) from changes in values of Level 3 financial instruments represent gains (losses) from changes in values of those financial instruments only for the periods in which the instruments were classified as Level 3.
	-2	Included in net realized investment gains (losses) and net investment income.
	-3	Included in fair value gains (losses) on FG VIEs.
	-4	Recorded in fair value gains (losses) on CCS.
	-5	Represents net position of credit derivatives. The consolidated balance sheet presents gross assets and liabilities based on net counterparty exposure.
	-6	Reported in net change in fair value of credit derivatives.
	-7	Reported in other income.
	-8	Non-cash transaction.
Fair Value, Liabilities Measured on Recurring Basis	The table below presents a roll forward of the Company’s Level 3 financial instruments carried at fair value on a recurring basis during the years ended December 31, 2014 and 2013.
	Fair Value Level 3 Rollforward
	Recurring Basis
	Year Ended December 31, 2014
		Fixed-Maturity Securities
		Obligations					Corporate Securities					RMBS					Asset-					Other				FG VIEs’					Other					Credit					FG VIEs' Liabilities					FG VIEs’ Liabilities
		of State and															Backed					Invested				Assets at					Assets					Derivative					with					without
		Political															Securities					Assets				Fair										Asset					Recourse,					Recourse,
		Subdivisions																								Value										(Liability),					at Fair					at Fair
																																				net(5)					Value					Value
		(in millions)
	Fair value as of December 31, 2013	$	36				$	136				$	290				$	268				$	2			$	2,565				$	46				$	(1,693	)			$	(1,790	)			$	(1,081	)
	Total pretax realized and unrealized gains/(losses) recorded in:(1)
	Net income (loss)	4			(2	)	(46		)	(2	)	21			(2	)	17			(2	)	—				164			(3	)	(11		)	(4	)	823			(6	)	94			(3	)	(43		)	(3	)
	Other comprehensive income (loss)	(1		)			(6		)			24					5					6				—					—					—					—					—
	Purchases	—					—					263					—					70				—					—					—					—					—
	Settlements	(1		)			(5		)			(59		)			(62		)			0				(408		)			—					(25		)			374					22
	FG VIE consolidations	—					—					(127		)			—					—				206					—					—					(189		)			(42		)
	FG VIE deconsolidations	—					—					13					—					—				(1,129		)			—					—					234					1,002
	Fair value as of December 31, 2014	$	38				$	79				$	425				$	228				$	78			$	1,398				$	35				$	(895	)			$	(1,277	)			$	(142	)
	Change in unrealized gains/(losses) related to financial instruments held as of December 31, 2014	$	(1	)			$	(6	)			$	21				$	4				$	6			$	141				$	(11	)			$	254				$	(22	)			$	3
	Fair Value Level 3 Rollforward
	Recurring Basis
	Year Ended December 31, 2013
		Fixed-Maturity Securities
		Obligations of state and political subdivisions					Corporate Securities					RMBS					Asset Backed Securities					Other					FG VIEs’					Other					Credit					FG VIEs’ Liabilities					FG VIEs’ Liabilities
																						Invested					Assets at					Assets					Derivative					with					without
																						Assets					Fair										Asset					Recourse,					Recourse,
																											Value										(Liability),					at Fair					at Fair
																																					net(5)					Value					Value
		(in millions)
	Fair value as of December 31, 2012	$	35				$	—				$	219				$	306				$	1				$	2,688				$	36				$	(1,793	)			$	(2,090	)			$	(1,051	)
	Total pretax realized and unrealized gains/(losses) recorded in:(1)
	Net income (loss)	(8		)	(2	)	4			(2	)	13			(2	)	67			(2	)	(1		)	(7	)	686			(3	)	10			(4	)	65			(6	)	(166		)	(3	)	(225		)	(3	)
	Other comprehensive income (loss)	13					5					26					(43		)			2					—					—					—					—					—
	Purchases	—					130			(8	)	86					80					2			(8	)	—					—					—					—					—
	Settlements	(4		)			(3		)			(54		)			(142		)			(2		)			(663		)			—					35					343					168
	FG VIE consolidations	—					—					—					—					—					48					—					—					(12		)			(37		)
	FG VIE deconsolidations	—					—					—					—					—					(194		)			—					—					135					64
	Fair value as of December 31, 2013	$	36				$	136				$	290				$	268				$	2				$	2,565				$	46				$	(1,693	)			$	(1,790	)			$	(1,081	)
	Change in unrealized gains/(losses) related to financial instruments held as of December 31, 2013	$	14				$	5				$	27				$	(20	)			$	2				$	623				$	10				$	(139	)			$	(169	)			$	(326	)
	___________________
	-1	Realized and unrealized gains (losses) from changes in values of Level 3 financial instruments represent gains (losses) from changes in values of those financial instruments only for the periods in which the instruments were classified as Level 3.
	-2	Included in net realized investment gains (losses) and net investment income.
	-3	Included in fair value gains (losses) on FG VIEs.
	-4	Recorded in fair value gains (losses) on CCS.
	-5	Represents net position of credit derivatives. The consolidated balance sheet presents gross assets and liabilities based on net counterparty exposure.
	-6	Reported in net change in fair value of credit derivatives.
	-7	Reported in other income.
	-8	Non-cash transaction.
Schedule of Quantitative Information About Level 3 Assets, Fair Value Measurements	Quantitative Information About Level 3 Fair Value Inputs
	At December 31, 2014
	Financial Instrument Description(1)		Fair Value at December 31, 2014(in millions)				Significant Unobservable Inputs		Range						Weighted Average as a Percentage of Current Par Outstanding
	Assets:
	Fixed-maturity securities:
	Obligations of state and political subdivisions		$	38			Rate of inflation		1		%	-	3.00%		2.00%
							Cash flow receipts		0.5		%	-	74.30%		63.00%
							Yield		4.6		%		8.00%		7.30%
							Collateral recovery period		1 month			-	34 years		28 years
	Corporate securities		79				Yield		17.80%
	RMBS		425				CPR		0.3		%	-	8.10%		3.30%
							CDR		2.7		%	-	10.60%		5.30%
							Loss severity		52.6		%	-	100.00%		75.20%
							Yield		4.7		%	-	11.70%		6.40%
	Asset-backed securities:
	Investor owned utility		95				Cash flow receipts		100.00%
							Collateral recovery period		4 years
							Discount factor		7.00%
	XXX life insurance transactions		133				Yield		7.30%
	Other invested assets		83				Discount for lack of liquidity		20.00%
							Recovery on delinquent loans		40.00%
							Default rates		0		%	-	7.00%		5.80%
							Loss severity		40		%	-	75.00%		68.30%
							Prepayment speeds		5		%	-	15.00%		12.30%
							Net asset value (per share)		$	965		-	$1,159		$1,082
	FG VIEs’ assets, at fair value		1,398				CPR		0.3		%	-	11.00%		3.30%
							CDR		1.6		%	-	11.80%		5.10%
							Loss severity		40		%	-	100.00%		82.20%
							Yield		2.7		%	-	17.70%		7.90%
	Financial Instrument Description(1)		Fair Value at			Significant Unobservable Inputs		Range					Weighted Average as a Percentage of Current Par Outstanding
			December 31, 2014
			(in millions)
	Other assets		35			Quotes from third party pricing		$52		-	$61		$57
						Term (years)		5 years
	Liabilities:
	Credit derivative liabilities, net		(895	)		Year 1 loss estimates		0	%	-	93.00%		2.10%
						Hedge cost (in bps)		20		-	243.8		61.5
						Bank profit (in bps)		1		-	994.4		127
						Internal floor (in bps)		7		-	100		15.9
						Internal credit rating		AAA		-	CCC		AA+
	FG VIEs’ liabilities, at fair value		(1,419	)		CPR		0.3	%	-	11.00%		3.30%
						CDR		1.6	%	-	11.80%		5.10%
						Loss severity		40	%	-	100.00%		82.20%
						Yield		2.7	%	-	17.70%		5.80%
	____________________
	-1	Discounted cash flow is used as valuation technique for all financial instruments.
	Quantitative Information About Level 3 Fair Value Inputs
	At December 31, 2013
	Financial Instrument Description(1)		Fair Value at December 31, 2013(in millions)				Significant Unobservable Inputs		Range						Weighted Average as a Percentage of Current Par Outstanding
	Assets:
	Fixed-maturity securities:
	Obligations of state and political subdivisions		$	36			Rate of inflation		1		%	-	3.00%		2.00%
							Cash flow receipts		0.5		%	-	60.90%		51.10%
							Discount rates		4.6		%	-	9.00%		8.00%
							Collateral recovery period		1 month			-	10 years		3 years
	Corporate securities		136				Yield		8.30%
	RMBS		290				CPR		1		%	-	15.80%		4.10%
							CDR		5		%	-	25.80%		17.90%
							Loss severity		48.1		%	-	102.50%		87.20%
							Yield		2.5		%	-	9.40%		5.70%
	Asset-backed securities:
	Investor owned utility		141				Liquidation value (in millions)			$195		-	$245		$228
							Years to liquidation		0 years			-	3 years		2 years
							Collateral recovery period		12 months			-	6 years		3.5 years
						Discount factor		15.30%
XXX life insurance transactions		127				Yield		12.50%
Other invested assets		8				Discount for lack of liquidity		10		%	-	20.00%		20.00%
						Recovery on delinquent loans		20		%	-	60.00%		40.00%
						Default rates		1		%	-	10.00%		3.20%
						Loss severity		40		%	-	90.00%		73.50%
						Prepayment speeds		6		%	-	15.00%		13.10%
FG VIEs’ assets, at fair value		2,565				CPR		0.3		%	-	11.80%		3.60%
						CDR		3		%	-	25.80%		13.60%
						Loss severity		37.5		%	-	102.00%		94.60%
						Yield		3.5		%	-	10.20%		5.40%
Financial Instrument Description(1)		Fair Value at			Significant Unobservable Inputs		Range					Weighted Average as a Percentage of Current Par Outstanding
		December 31, 2013
		(in millions)
Other assets		46			Quotes from third party pricing		$47		-	$53		$50
					Term (years)		5 years
Liabilities:
Credit derivative liabilities, net		(1,693	)		Year 1 loss estimates		0	%	-	48.00%		1.90%
					Hedge cost (in bps)		46.3		-	525		110.1
					Bank profit (in bps)		1		-	1,418.50		250.4
					Internal floor (in bps)		7		-	100		15.6
					Internal credit rating		AAA		-	CCC		AA+
FG VIEs’ liabilities, at fair value		(2,871	)		CPR		0.3	%	-	11.80%		3.60%
					CDR		3	%	-	25.80%		13.60%
					Loss severity		37.5	%	-	102.00%		94.60%
					Yield		3.5	%	-	10.20%		5.40%
____________________
-1	Discounted cash flow is used as valuation technique for all financial instruments.
Schedule of Quantitative Information About Level 3 Liabilities, Fair Value Measurements	Quantitative Information About Level 3 Fair Value Inputs
	At December 31, 2014
	Financial Instrument Description(1)		Fair Value at December 31, 2014(in millions)				Significant Unobservable Inputs		Range						Weighted Average as a Percentage of Current Par Outstanding
	Assets:
	Fixed-maturity securities:
	Obligations of state and political subdivisions		$	38			Rate of inflation		1		%	-	3.00%		2.00%
							Cash flow receipts		0.5		%	-	74.30%		63.00%
							Yield		4.6		%		8.00%		7.30%
							Collateral recovery period		1 month			-	34 years		28 years
	Corporate securities		79				Yield		17.80%
	RMBS		425				CPR		0.3		%	-	8.10%		3.30%
							CDR		2.7		%	-	10.60%		5.30%
							Loss severity		52.6		%	-	100.00%		75.20%
							Yield		4.7		%	-	11.70%		6.40%
	Asset-backed securities:
	Investor owned utility		95				Cash flow receipts		100.00%
							Collateral recovery period		4 years
							Discount factor		7.00%
	XXX life insurance transactions		133				Yield		7.30%
	Other invested assets		83				Discount for lack of liquidity		20.00%
							Recovery on delinquent loans		40.00%
							Default rates		0		%	-	7.00%		5.80%
							Loss severity		40		%	-	75.00%		68.30%
							Prepayment speeds		5		%	-	15.00%		12.30%
							Net asset value (per share)		$	965		-	$1,159		$1,082
	FG VIEs’ assets, at fair value		1,398				CPR		0.3		%	-	11.00%		3.30%
							CDR		1.6		%	-	11.80%		5.10%
							Loss severity		40		%	-	100.00%		82.20%
							Yield		2.7		%	-	17.70%		7.90%
	Financial Instrument Description(1)		Fair Value at			Significant Unobservable Inputs		Range					Weighted Average as a Percentage of Current Par Outstanding
			December 31, 2014
			(in millions)
	Other assets		35			Quotes from third party pricing		$52		-	$61		$57
						Term (years)		5 years
	Liabilities:
	Credit derivative liabilities, net		(895	)		Year 1 loss estimates		0	%	-	93.00%		2.10%
						Hedge cost (in bps)		20		-	243.8		61.5
						Bank profit (in bps)		1		-	994.4		127
						Internal floor (in bps)		7		-	100		15.9
						Internal credit rating		AAA		-	CCC		AA+
	FG VIEs’ liabilities, at fair value		(1,419	)		CPR		0.3	%	-	11.00%		3.30%
						CDR		1.6	%	-	11.80%		5.10%
						Loss severity		40	%	-	100.00%		82.20%
						Yield		2.7	%	-	17.70%		5.80%
	____________________
	-1	Discounted cash flow is used as valuation technique for all financial instruments.
	Quantitative Information About Level 3 Fair Value Inputs
	At December 31, 2013
	Financial Instrument Description(1)		Fair Value at December 31, 2013(in millions)				Significant Unobservable Inputs		Range						Weighted Average as a Percentage of Current Par Outstanding
	Assets:
	Fixed-maturity securities:
	Obligations of state and political subdivisions		$	36			Rate of inflation		1		%	-	3.00%		2.00%
							Cash flow receipts		0.5		%	-	60.90%		51.10%
							Discount rates		4.6		%	-	9.00%		8.00%
							Collateral recovery period		1 month			-	10 years		3 years
	Corporate securities		136				Yield		8.30%
	RMBS		290				CPR		1		%	-	15.80%		4.10%
							CDR		5		%	-	25.80%		17.90%
							Loss severity		48.1		%	-	102.50%		87.20%
							Yield		2.5		%	-	9.40%		5.70%
	Asset-backed securities:
	Investor owned utility		141				Liquidation value (in millions)			$195		-	$245		$228
							Years to liquidation		0 years			-	3 years		2 years
							Collateral recovery period		12 months			-	6 years		3.5 years
						Discount factor		15.30%
XXX life insurance transactions		127				Yield		12.50%
Other invested assets		8				Discount for lack of liquidity		10		%	-	20.00%		20.00%
						Recovery on delinquent loans		20		%	-	60.00%		40.00%
						Default rates		1		%	-	10.00%		3.20%
						Loss severity		40		%	-	90.00%		73.50%
						Prepayment speeds		6		%	-	15.00%		13.10%
FG VIEs’ assets, at fair value		2,565				CPR		0.3		%	-	11.80%		3.60%
						CDR		3		%	-	25.80%		13.60%
						Loss severity		37.5		%	-	102.00%		94.60%
						Yield		3.5		%	-	10.20%		5.40%
Financial Instrument Description(1)		Fair Value at			Significant Unobservable Inputs		Range					Weighted Average as a Percentage of Current Par Outstanding
		December 31, 2013
		(in millions)
Other assets		46			Quotes from third party pricing		$47		-	$53		$50
					Term (years)		5 years
Liabilities:
Credit derivative liabilities, net		(1,693	)		Year 1 loss estimates		0	%	-	48.00%		1.90%
					Hedge cost (in bps)		46.3		-	525		110.1
					Bank profit (in bps)		1		-	1,418.50		250.4
					Internal floor (in bps)		7		-	100		15.6
					Internal credit rating		AAA		-	CCC		AA+
FG VIEs’ liabilities, at fair value		(2,871	)		CPR		0.3	%	-	11.80%		3.60%
					CDR		3	%	-	25.80%		13.60%
					Loss severity		37.5	%	-	102.00%		94.60%
					Yield		3.5	%	-	10.20%		5.40%
____________________
-1	Discounted cash flow is used as valuation technique for all financial instruments.
Fair Value of Financial Instruments	The carrying amount and estimated fair value of the Company’s financial instruments are presented in the following table.
	Fair Value of Financial Instruments
		As of								As of
		31-Dec-14								31-Dec-13
		Carrying				Estimated				Carrying				Estimated
		Amount				Fair Value				Amount				Fair Value
		(in millions)
	Assets:
	Fixed-maturity securities	$	10,491			$	10,491			$	9,711			$	9,711
	Short-term investments	767				767				904				904
	Other invested assets	108				110				147				155
	Credit derivative assets	68				68				94				94
	FG VIEs’ assets, at fair value	1,398				1,398				2,565				2,565
	Other assets	184				184				179				179
	Liabilities:
	Financial guaranty insurance contracts(1)	3,823				6,205				3,783				5,128
	Long-term debt	1,303				1,603				816				970
	Credit derivative liabilities	963				963				1,787				1,787
	FG VIEs’ liabilities with recourse, at fair value	1,277				1,277				1,790				1,790
	FG VIEs’ liabilities without recourse, at fair value	142				142				1,081				1,081
	Other liabilities	27				27				36				36
	____________________
	-1	Carrying amount includes the assets and liabilities related to financial guaranty insurance contract premiums, losses, and salvage and subrogation and other recoverables net of reinsurance.

Financial_Guaranty_Contracts_A1

Financial Guaranty Contracts Accounted for as Credit Derivatives (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Credit Derivatives Subordination and Ratings and Net Par Outstanding by Internal Rating	Credit Derivatives
	Subordination and Ratings
			As of December 31, 2014												As of December 31, 2013
	Asset Type		Net Par				Original			Current			Weighted		Net Par			Original		Current		Weighted
			Outstanding				Subordination(1)			Subordination(1)			Average		Outstanding			Subordination(1)		Subordination(1)		Average
													Credit									Credit
													Rating									Rating
			(dollars in millions)
	Pooled corporate obligations:
	Collateralized loan obligation/collateral bond obligations		$	11,688			32	%		36.9	%		AAA		$	19,323		32.4	%	34	%	AAA
	Synthetic investment grade pooled corporate		7,640				22.6			20.6			AAA		9,754			21.6		20		AAA
	Synthetic high yield pooled corporate		—				—			—			—		2,690			47.2		41.1		AAA
	TruPS CDOs		3,119				45.3			35.8			BBB-		3,554			45.5		32.9		BB+
	Market value CDOs of corporate obligations		1,174				19.1			20.7			AAA		2,000			24.4		30.5		AAA
	Total pooled corporate obligations		23,621				30.1			30.7			AAA		37,321			31.5		30.6		AAA
	U.S. RMBS:
	Option ARM and Alt-A first lien		1,378				16.3			10.7			BB+		2,609			19.2		8.6		BB-
	Subprime first lien		1,366				31.1			50.5			A		2,930			30.5		51.9		AA-
	Prime first lien		223				10.9			0			B		264			10.9		3.2		CCC
	Closed-end second lien		19				—			—			CCC		23			—		—		B+
	Total U.S. RMBS		2,986				24.8			33.9			BBB		5,826			24.4		30.1		BBB
	CMBS		1,952				35.3			43.6			AAA		3,744			33.5		42.5		AAA
	Other		6,437				—			—			A		7,591			—		—		A-
	Total		$	34,996									AA+		$	54,482						AA+
	____________________
	-1	Represents the sum of subordinate tranches and over-collateralization and does not include any benefit from excess interest collections that may be used to absorb losses.
	Distribution of Credit Derivative Net Par Outstanding by Internal Rating
			As of December 31, 2014							As of December 31, 2013
	Ratings		Net Par				% of Total			Net Par				% of Total
			Outstanding							Outstanding
			(dollars in millions)
	AAA		$	21,817			62.3	%		$	38,244			70.2	%
	AA		5,398				15.4			3,648				6.7
	A		1,982				5.7			3,636				6.7
	BBB		2,774				8			4,161				7.6
	BIG		3,025				8.6			4,793				8.8
	Credit derivative net par outstanding		$	34,996			100	%		$	54,482			100	%
Net Change in Fair Value of Credit Derivatives	Net Change in Fair Value of Credit Derivatives Gain (Loss)
		Year Ended December 31,
		2014				2013				2012
		(in millions)
	Realized gains on credit derivatives	$	73			$	121			$	128
	Net credit derivative losses (paid and payable) recovered and recoverable and other settlements	(50		)		(163		)		(236		)
	Realized gains (losses) and other settlements on credit derivatives	23				(42		)		(108		)
	Net change in unrealized gains (losses) on credit derivatives:
	Pooled corporate obligations	(18		)		(32		)		59
	U.S. RMBS	814				(69		)		(551		)
	CMBS	2				—				2
	Other(1)	2				208				13
	Net change in unrealized gains (losses) on credit derivatives(2)	800				107				(477		)
	Net change in fair value of credit derivatives	$	823			$	65			$	(585	)
	____________________
	-1	“Other” includes all other U.S. and international asset classes, such as commercial receivables, international infrastructure, international RMBS securities, and pooled infrastructure securities.
	-2	Except for net estimated credit impairments (i.e., net expected loss to be paid as discussed in Note 6), the unrealized gains and losses on credit derivatives are expected to reduce to zero as the exposure approaches its maturity date. With considerable volatility continuing in the market, unrealized gains (losses) on credit derivatives may fluctuate significantly in future periods.
Net Par and Accelerations of Credit Derivative Revenues from Termination of CDS Contracts	Net Par and Realized Gains (Losses) on Credit Derivatives
	from Terminations of CDS Contracts
		Year Ended December 31,
		2014				2013				2012
		(in millions)
	Net par of terminated CDS contracts	$	3,591			$	4,054			$	2,264
	Realized gains (losses) and other settlements	1				21				3
CDS Spread on AGC and AGM	Five-Year CDS Spread
	on AGC and AGM
	Quoted price of CDS contract (in basis points)
		As of			As of			As of
		31-Dec-14			31-Dec-13			31-Dec-12
	AGC	323			460			678
	AGM	325			525			536
	One-Year CDS Spread
	on AGC and AGM
	Quoted price of CDS contract (in basis points)
		As of			As of			As of
		31-Dec-14			31-Dec-13			31-Dec-12
	AGC	80			185			270
	AGM	85			220			257
Fair Value of Credit Derivatives and Effect of AGC and AGM Credit Spreads	Fair Value of Credit Derivatives Assets (Liabilities)
	and Effect of AGC and AGM
	Credit Spreads
		As of				As of
		31-Dec-14				31-Dec-13
		(in millions)
	Fair value of credit derivatives before effect of AGC and AGM credit spreads	$	(2,029	)		$	(3,442	)
	Plus: Effect of AGC and AGM credit spreads	1,134				1,749
	Net fair value of credit derivatives	$	(895	)		$	(1,693	)
Net Fair Value and Expected Losses of Credit Derivatives by Sector	Net Fair Value and Expected Losses
	Credit Derivatives by Sector
			Fair Value of Credit Derivative								Expected Loss to be (Paid) Recovered (1)
			Asset (Liability), net
	Asset Type		As of				As of				As of				As of
			31-Dec-14				31-Dec-13				31-Dec-14				31-Dec-13
			(in millions)
	Pooled corporate obligations		$	(49	)		$	(30	)		$	(23	)		$	(48	)
	U.S. RMBS		(494		)		(1,308		)		(73		)		(175		)
	CMBS		0				(2		)		—				—
	Other		(352		)		(353		)		38				39
	Total		$	(895	)		$	(1,693	)		$	(58	)		$	(184	)
	____________________
	(1)	Includes R&W benefit of $86 million as of December 31, 2014 and $180 million as of December 31, 2013.
Effects of Changes in Credit Spread	Effect of Changes in Credit Spread
	As of December 31, 2014
	Credit Spreads(1)		Estimated Net				Estimated Change
			Fair Value				in Gain/(Loss)
			(Pre-Tax)				(Pre-Tax)
			(in millions)
	100% widening in spreads		$	(1,821	)		$	(926	)
	50% widening in spreads		(1,358		)		(463		)
	25% widening in spreads		(1,128		)		(233		)
	10% widening in spreads		(989		)		(94		)
	Base Scenario		(895		)		—
	10% narrowing in spreads		(809		)		86
	25% narrowing in spreads		(679		)		216
	50% narrowing in spreads		(466		)		429
	____________________
	-1	Includes the effects of spreads on both the underlying asset classes and the Company’s own credit spread.

Consolidated_Variable_Interest1

Consolidated Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Consolidated FG VIE's	Effect of Consolidating FG VIEs on Net Income,
	Cash Flows From Operating Activities and Shareholders’ Equity
		Year Ended December 31,
		2014				2013				2012
		(in millions)
	Net earned premiums	$	(32	)		$	(60	)		$	(153	)
	Net investment income	(11		)		(13		)		(13		)
	Net realized investment gains (losses)	(5		)		2				4
	Fair value gains (losses) on FG VIEs	255				346				191
	Other income (loss)	(2		)		—				—
	Loss and LAE	30				21				65
	Effect on net income before tax	235				296				94
	Less: tax provision (benefit)	82				103				32
	Effect on net income (loss)	$	153			$	193			$	62
	Effect on cash flows from operating activities	$	68			$	(136	)		$	166
		As of				As of
		31-Dec-14				31-Dec-13
		(in millions)
	Effect on shareholders’ equity (decrease) increase	$	(44	)		$	(172	)
	Consolidated FG VIEs
	By Type of Collateral
		As of December 31, 2014								As of December 31, 2013
		Assets				Liabilities				Assets			Liabilities
		(in millions)
	With recourse:
	U.S. RMBS first lien	$	632			$	581			$	630		$	791
	U.S. RMBS second lien	238				327				460			640
	Other	369				369				359			359
	Total with recourse	1,239				1,277				1,449			1,790
	Without recourse	163				142				1,116			1,081
	Total	$	1,402			$	1,419			$	2,565		$	2,871
	Number of FG VIEs Consolidated
		Year Ended December 31,
		2014			2013			2012
	Beginning of the period, December 31	40			33			33
	Consolidated(1)	2			11			2
	Deconsolidated(1)	(8	)		(3	)		—
	Matured	(2	)		(1	)		(2	)
	End of the period, December 31	32			40			33
	____________________
	-1	Net gain on deconsolidation was $120 million and net loss on consolidation was $26 million in 2014. Net loss on consolidation and deconsolidation was $7 million in 2013 and $6 million in 2012, respectively, and recorded in “fair value gains (losses) on FG VIEs” in the consolidated statement of operations.

Investments_and_Cash_Tables

Investments and Cash (Tables)	12 Months Ended
	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Net Investment Income	Net Investment Income
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Income from fixed-maturity securities managed by third parties	$	324		$	322		$	346
	Income from internally managed securities:
	Fixed maturities	74			74			60
	Other invested assets	13			5			6
	Other	1			0			1
	Gross investment income	412			401			413
	Investment expenses	(9		)	(8		)	(9		)
	Net investment income	$	403		$	393		$	404
Net Realized Investment Gains (Losses)	Net Realized Investment Gains (Losses)
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Gross realized gains on available-for-sale securities	$	14		$	73		$	29
	Gross realized gains on other assets in investment portfolio	8			40			14
	Gross realized losses on available-for-sale securities	(5		)	(12		)	(23		)
	Gross realized losses on other assets in investment portfolio	(2		)	(7		)	(2		)
	Other-than-temporary impairment	(75		)	(42		)	(17		)
	Net realized investment gains (losses)	$	(60	)	$	52		$	1
Roll Forward of Credit Losses in the Investment Portfolio	Roll Forward of Credit Losses
	in the Investment Portfolio
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Balance, beginning of period	$	80		$	64		$	47
	Additions for credit losses on securities for which an other-than-temporary-impairment was not previously recognized	64			18			14
	Eliminations of securities issued by FG VIEs	(15		)	—			—
	Reductions for securities sold during the period	(12		)	(21		)	—
	Additions for credit losses on securities for which an other-than-temporary-impairment was previously recognized	7			19			3
	Balance, end of period	$	124		$	80		$	64
Fixed Maturity Securities and Short Term Investments by Security Type	Fixed-Maturity Securities and Short-Term Investments
	by Security Type
	As of December 31, 2014
	Investment Category		Percent		Amortized			Gross			Gross			Estimated			AOCI(2)			Weighted
			of		Cost			Unrealized			Unrealized			Fair			Gain			Average
			Total(1)					Gains			Losses			Value			(Loss) on			Credit
																	Securities			Quality
																	with			(3)
																	Other-Than-Temporary Impairment
			(dollars in millions)
	Fixed-maturity securities:
	Obligations of state and political subdivisions		50	%	$	5,416		$	380		$	(1	)	$	5,795		$	7		AA
	U.S. government and agencies		6		635			31			(1		)	665			—			AA+
	Corporate securities		12		1,320			53			(5		)	1,368			(2		)	A
	Mortgage-backed securities(4):		—
	RMBS		12		1,255			51			(21		)	1,285			0			A-
	CMBS		6		639			20			0			659			—			AAA
	Asset-backed securities		4		411			9			(3		)	417			3			BBB-
	Foreign government securities		3		296			8			(2		)	302			—			AA+
	Total fixed-maturity securities		93		9,972			552			(33		)	10,491			8			AA-
	Short-term investments		7		767			0			0			767			0			AA+
	Total investment portfolio		100	%	$	10,739		$	552		$	(33	)	$	11,258		$	8		AA-
	Fixed-Maturity Securities and Short-Term Investments
	by Security Type
	As of December 31, 2013
	Investment Category		Percent		Amortized			Gross			Gross			Estimated			AOCI			Weighted
			of		Cost			Unrealized			Unrealized			Fair			Gain			Average
			Total(1)					Gains			Losses			Value			(Loss) on			Credit
																	Securities			Quality
																	with			(3)
																	Other-Than-Temporary Impairment
			(dollars in millions)
	Fixed-maturity securities:
	Obligations of state and political subdivisions		47	%	$	4,899		$	219		$	(39	)	$	5,079		$	4		AA
	U.S. government and agencies		6		674			32			(6		)	700			—			AA+
	Corporate securities		13		1,314			44			(18		)	1,340			0			A
	Mortgage-backed securities(4):
	RMBS		11		1,160			34			(72		)	1,122			(43		)	A
	CMBS		5		536			17			(4		)	549			—			AAA
	Asset-backed securities		6		605			10			(7		)	608			2			BBB+
	Foreign government securities		3		300			14			(1		)	313			—			AA+
	Total fixed-maturity securities		91		9,488			370			(147		)	9,711			(37		)	AA-
	Short-term investments		9		904			0			0			904			—			AAA
	Total investment portfolio		100	%	$	10,392		$	370		$	(147	)	$	10,615		$	(37	)	AA-
	____________________
	-1	Based on amortized cost.
	-2	Accumulated OCI. See also Note 21, Other Comprehensive Income.
	-3	Ratings in the tables above represent the lower of the Moody’s and S&P classifications except for bonds purchased for loss mitigation or risk management strategies, which use internal ratings classifications. The Company’s portfolio consists primarily of high-quality, liquid instruments.
	-4	Government-agency obligations were approximately 44% of mortgage backed securities as of December 31, 2014 and 50% as of December 31, 2013 based on fair value.
Fair Value of Available-for-Sale Municipal Bond Portfolio by State	Fair Value of Available-for-Sale Portfolio of
	Obligations of State and Political Subdivisions
	As of December 31, 2014 (1)
	State		State			Local			Revenue Bonds			Fair			Amortized			Average
			General			General						Value			Cost			Credit
			Obligation			Obligation												Rating
			(in millions)
	Texas		$	60		$	293		$	305		$	658		$	613		AA
	New York		13			41			551			605			571			AA
	California		45			70			377			492			449			A+
	Florida		47			34			256			337			311			AA-
	Illinois		20			99			177			296			275			A+
	Washington		67			48			163			278			262			AA
	Massachusetts		46			8			169			223			204			AA
	Arizona		—			7			170			177			165			AA
	Michigan		—			—			132			132			122			AA-
	Ohio		6			40			82			128			119			AA
	All others		276			251			1,096			1,623			1,528			AA-
	Total		$	580		$	891		$	3,478		$	4,949		$	4,619
	Fair Value of Available-for-Sale Portfolio of
	Obligations of State and Political Subdivisions
	As of December 31, 2013 (1)
	State		State			Local			Revenue Bonds			Fair			Amortized			Average
			General			General						Value			Cost			Credit
			Obligation			Obligation												Rating
			(in millions)
	Texas		$	77		$	299		$	277		$	653		$	629		AA
	New York		12			58			519			589			575			AA
	California		32			86			354			472			452			A+
	Florida		33			59			242			334			318			AA-
	Illinois		14			70			156			240			234			A+
	Massachusetts		44			16			147			207			200			AA
	Washington		31			19			153			203			199			AA
	Arizona		—			7			166			173			170			AA
	Michigan		—			28			102			130			125			AA-
	Georgia		13			18			97			128			128			A+
	All others		254			228			943			1,425			1,381			AA-
	Total		$	510		$	888		$	3,156		$	4,554		$	4,411		AA-
	____________________
	-1	Excludes $846 million and $525 million as of December 31, 2014 and 2013, respectively, of pre-refunded bonds, at fair value. The credit ratings are based on the underlying ratings and do not include any benefit from bond insurance.
Revenue Sources	Revenue Bonds
	Sources of Funds
			As of December 31, 2014						As of December 31, 2013
	Type		Fair			Amortized			Fair			Amortized
			Value			Cost			Value			Cost
			(in millions)
	Transportation		$	796		$	733		$	642		$	615
	Water and sewer		563			527			459			453
	Tax backed		551			514			708			686
	Higher education		527			492			358			353
	Municipal utilities		512			479			500			482
	Healthcare		346			317			289			281
	All others		183			173			200			192
	Total		$	3,478		$	3,235		$	3,156		$	3,062
Fixed Maturity Securities Gross Unrealized Loss by Length of Time	Fixed-Maturity Securities
	Gross Unrealized Loss by Length of Time
	As of December 31, 2014
		Less than 12 months						12 months or more						Total
		Fair			Unrealized			Fair			Unrealized			Fair			Unrealized
		Value			Loss			Value			Loss			Value			Loss
		(dollars in millions)
	Obligations of state and political subdivisions	$	64		$	0		$	25		$	(1	)	$	89		$	(1	)
	U.S. government and agencies	139			0			68			(1		)	207			(1		)
	Corporate securities	189			(3		)	104			(2		)	293			(5		)
	Mortgage-backed securities:
	RMBS	205			(3		)	159			(18		)	364			(21		)
	CMBS	36			0			19			0			55			0
	Asset-backed securities	56			(2		)	18			(1		)	74			(3		)
	Foreign government securities	108			(2		)	0			0			108			(2		)
	Total	$	797		$	(10	)	$	393		$	(23	)	$	1,190		$	(33	)
	Number of securities(1)				125						82						198
	Number of securities with other-than-temporary impairment				3						7						10
	Fixed-Maturity Securities
	Gross Unrealized Loss by Length of Time
	As of December 31, 2013
		Less than 12 months						12 months or more						Total
		Fair			Unrealized			Fair			Unrealized			Fair			Unrealized
		Value			Loss			Value			Loss			Value			Loss
		(dollars in millions)
	Obligations of state and political subdivisions	$	781		$	(39	)	$	5		$	0		$	786		$	(39	)
	U.S. government and agencies	173			(6		)	—			—			173			(6		)
	Corporate securities	401			(18		)	3			0			404			(18		)
	Mortgage-backed securities:
	RMBS	414			(21		)	186			(51		)	600			(72		)
	CMBS	121			(4		)	—			—			121			(4		)
	Asset-backed securities	196			(2		)	42			(5		)	238			(7		)
	Foreign government securities	54			(1		)	1			0			55			(1		)
	Total	$	2,140		$	(91	)	$	237		$	(56	)	$	2,377		$	(147	)
	Number of securities				425						33						458
	Number of securities with other-than-temporary impairment				13						11						24
	___________________
	-1	The number of securities does not add across because of lots of the same securities that have been purchased at different times and appear in both categories above (i.e., Less than 12 months and 12 months or more). If a security appears in both categories, it is counted only once in the Total column.
	Of the
Distribution of Fixed Maturity Securities by Contractual Maturity	Distribution of Fixed-Maturity Securities
	by Contractual Maturity
	As of December 31, 2014
		Amortized			Estimated
		Cost			Fair Value
		(in millions)
	Due within one year	$	111		$	112
	Due after one year through five years	1,961			2,028
	Due after five years through 10 years	2,286			2,422
	Due after 10 years	3,720			3,985
	Mortgage-backed securities:
	RMBS	1,255			1,285
	CMBS	639			659
	Total	$	9,972		$	10,491
Internally Managed Investment Portfolio	Internally Managed Portfolio
	Carrying Value
		As of December 31,
		2014			2013
		(in millions)
	Assets purchased for loss mitigation and other risk management purposes:
	Fixed maturity securities	$	835		$	761
	Other invested assets	46			82
	Other	79			88
	Total	$	960		$	931

Insurance_Company_Regulatory_R1

Insurance Company Regulatory Requirements (Tables)	12 Months Ended
	Dec. 31, 2014
Insurance Company Regulatory Requirements [Abstract]
Schedule of Statutory Capital and Surplus and Net Income	Insurance Regulatory Amounts Reported
		Policyholders' Surplus					Net Income (Loss)
		As of December 31,					Year Ended December 31,
		2014		2013			2014		2013		2012
		(in millions)
	U.S. statutory companies:
	AGM(1)	$	2,267	$	1,733		$	304	$	340	$	203
	MAC	$	612	$	514		$	75	$	26	$	1
	AGC(1)	1,086		693			116		211		31
	Bermuda statutory company:
	AG Re	1,114		1,119			28		103		117
	____________________
	-1	Policyholders' surplus of AGM and AGC include their indirect share of MAC. AGM and AGC own approximately 61% and 39%, respectively, of the outstanding stock of Municipal Assurance Holdings Inc. ("MAC Holdings"), which owns 100% of the outstanding common stock of MAC.
Schedule of Dividends Paid by Insurance Company Subsidiaries	Dividends and Surplus Notes
	By Insurance Company Subsidiaries
		Year Ended December 31,
		2014		2013			2012
		(in millions)
	Dividends paid by AGC to AGUS	$	69	$	67		$	55
	Dividends paid by AGM to AGMH	160		163			30
	Dividends paid by AG Re to AGL	82		144			151
	Repayment of surplus note by AGM to AGMH	50		50			50
	Issuance of surplus notes by MAC to MAC Holdings	—		(300		)	—
	Issuance of surplus notes by MAC to AGM	—		(100		)	—

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Effective Tax Rate Reconciliation	Effective Tax Rate Reconciliation
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	Expected tax provision (benefit) at statutory rates in taxable jurisdictions	$	490		$	390		$	76
	Tax-exempt interest	(53		)	(57		)	(61		)
	Change in liability for uncertain tax positions	9			(2		)	2
	Other	(3		)	3			5
	Total provision (benefit) for income taxes	$	443		$	334		$	22
	Effective tax rate	28.9		%	29.2		%	16.5		%
Pretax Income (Loss) by Tax Jurisdiction	Pretax Income (Loss) by Tax Jurisdiction
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	United States	$	1,420		$	1,118		$	218
	Bermuda	142			27			(86		)
	U.K.	(31		)	(3		)	0
	Total	$	1,531		$	1,142		$	132
Revenue by Tax Jurisdiction	Revenue by Tax Jurisdiction
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	United States	$	1,633		$	1,389		$	875
	Bermuda	365			219			79
	U.K.	(4		)	0			0
	Total	$	1,994		$	1,608		$	954
Components of Deferred Tax Assets and Liabilities	Components of Net Deferred Tax Assets
		As of December 31,
		2014			2013
		(in millions)
	Deferred tax assets:
	Unrealized losses on credit derivative financial instruments, net	$	224		$	402
	Unearned premium reserves, net	63			63
	Loss and LAE reserve	66			134
	Tax and loss bonds	39			33
	Alternative minimum tax credit	57			90
	Foreign tax credit	—			37
	FG VIEs	13			29
	DAC	35			40
	Investment basis difference	104			93
	Deferred compensation	38			33
	Other	19			21
	Total deferred income tax assets	658			975
	Deferred tax liabilities:
	Contingency reserves	64			47
	Public debt	96			98
	Unrealized appreciation on investments	159			68
	Unrealized gains on CCS	22			16
	Market discount	36			24
	Other	21			34
	Total deferred income tax liabilities	398			287
	Net deferred income tax asset	$	260		$	688
Reconciliation of Uncertain Tax Positions	The following table provides a reconciliation of the beginning and ending balances of the total liability for unrecognized tax benefits. The Company does not believe it is reasonably possible that this amount will change significantly in the next twelve months.
		2014			2013			2012
		(in millions)
	Balance as of January 1,	$	20		$	22		$	20
	True-up from tax return filings	6			4			—
	Increase in unrecognized tax benefits as a result of position taken during the current period	2			3			2
	Decrease due to closing of IRS audit	—			(9		)	—
	Balance as of December 31,	$	28		$	20		$	22

Reinsurance_and_Other_Monoline1

Reinsurance and Other Monoline Exposures (Tables)	12 Months Ended
	Dec. 31, 2014
Insurance [Abstract]
Net Effect of Commutations and Cancellations of Assumed Reinsurance Contracts	Net Effect of Commutations of Ceded and
	Cancellations of Assumed Reinsurance Contracts
		Year Ended December 31,
		2014				2013				2012
		(in millions)
	Increase (decrease) in net unearned premium reserve	$	20			$	11			$	109
	Increase (decrease) in net par outstanding	1,167				151				19,173
	Commutation gains recorded in other income	23				2				82
Effects of Reinsurance on Statement of Operations	Effect of Reinsurance on Statement of Operations
		Year Ended December 31,
		2014				2013				2012
		(in millions)
	Premiums Written:
	Direct	$	116			$	106			244
	Assumed(1)	(12		)		17				9
	Ceded(2)	15				2				51
	Net	$	119			$	125			304
	Premiums Earned:
	Direct	$	581			$	819			936
	Assumed	47				40				50
	Ceded	(58		)		(107		)		(133	)
	Net	$	570			$	752			853
	Loss and LAE:
	Direct	$	132			$	110			636
	Assumed	37				73				(4	)
	Ceded	(43		)		(29		)		(128	)
	Net	$	126			$	154			504
	____________________
	-1	Negative assumed premiums written were due to cancellations and changes in expected Debt Service schedules.
	-2	Positive ceded premiums written were due to commutations and changes in expected Debt Service schedules.
Exposure by Reinsurer	Exposure by Reinsurer
			Ratings at				Par Outstanding (1)
			February 24, 2015				As of December 31, 2014
	Reinsurer		Moody’s		S&P		Ceded Par				Second-to-				Assumed Par
			Reinsurer		Reinsurer		Outstanding				Pay Insured				Outstanding
			Rating		Rating						Par
											Outstanding
			(dollars in millions)
	American Overseas Reinsurance Company Limited (f/k/a Ram Re)		WR (2)		WR		$	6,727			$	—			$	30
	Tokio Marine & Nichido Fire Insurance Co., Ltd. (“Tokio”)		Aa3 (3)		AA- (3)		5,276				—				—
	Radian Asset		Ba1		B+		4,104				21				671
	Syncora Guarantee Inc.		WR		WR		3,715				1,514				161
	Mitsui Sumitomo Insurance Co. Ltd.		A1		A+ (3)		2,033				—				—
	ACA Financial Guaranty Corp.		NR (5)		WR		746				2				—
	Swiss Reinsurance Co.		Aa3		AA-		93				—				—
	Ambac		WR		WR		82				4,930				14,342
	National Public Finance Guarantee Corporation		A3		AA-		—				6,210				5,894
	MBIA		-4		-4		—				2,613				587
	FGIC		WR		WR		—				2,074				834
	Ambac Assurance Corp. Segregated Account		NR		NR		—				109				956
	CIFG Assurance North America Inc. ("CIFG")		WR		WR		—				102				4,365
	Other		Various		Various		199				894				46
	Total						$	22,975			$	18,469			$	27,886
	____________________
	-1	Includes par related to insured credit derivatives.
	(2)    Represents “Withdrawn Rating.”
	(3)    The Company has structural collateral agreements satisfying the triple-A credit requirement of S&P and/or Moody’s.
	-4	MBIA includes subsidiaries MBIA Insurance Corp. rated B by S&P and B2 by Moody's and MBIA U.K. Insurance Ltd. rated B by S&P and Ba2 by Moody’s.
	-5	Represents “Not Rated.”
	Ceded Par Outstanding by Reinsurer and Credit Rating
	As of December 31, 2014
				Internal Credit Rating
	Reinsurer			AAA				AA				A				BBB				BIG				Total
				(in millions)
	American Overseas Reinsurance Company Limited (f/k/a Ram Re)			$	633			$	2,452			$	1,992			$	1,158			$	492			$	6,727
	Tokio			763				968				1,485				1,281				779				5,276
	Radian Asset			206				287				2,037				1,085				489				4,104
	Syncora Guarantee Inc.			—				291				498				2,193				733				3,715
	Mitsui Sumitomo Insurance Co. Ltd.			134				669				742				299				189				2,033
	ACA Financial Guaranty Corp			—				458				277				11				—				746
	Swiss Reinsurance Co.			—				—				0				26				67				93
	Ambac			—				—				82				—				—				82
	Other			62				82				55				—				—				199
	Total			$	1,798			$	5,207			$	7,168			$	6,053			$	2,749			$	22,975
Second-to-Pay Insured Par Outstanding by Internal Rating	Second-to-Pay
	Insured Par Outstanding by Internal Rating
	As of December 31, 2014(1)
		Public Finance																				Structured Finance
		AAA				AA				A				BBB				BIG				AAA				AA		A		BBB		BIG		Total
		(in millions)
	Radian Asset	$	—			$	—			$	3			$	12			$	6			$	—			$	—	$	—	$	—	$	—	$	21
	Syncora Guarantee Inc.	—				45				326				727				276				96				—		—		—		44		1,514
	ACA Financial Guaranty Corp.	—				1				—				1				—				—				—		—		—		—		2
	Ambac	30				1,301				2,597				637				63				—				1		64		231		6		4,930
	National Public Finance Guarantee Corporation	160				2,193				3,833				—				—				—				—		24		—		—		6,210
	MBIA	—				65				254				424				—				—				1,508		—		243		119		2,613
	FGIC	—				77				975				281				302				371				—		25		—		43		2,074
	Ambac Assurance Corp. Segregated Account	—				—				—				—				—				—				33		—		—		76		109
	CIFG	—				4				51				22				25				—				—		—		—		—		102
	Other	—				894				—				—				—				—				—		—		—		—		894
	Total	$	190			$	4,580			$	8,039			$	2,104			$	672			$	467			$	1,542	$	113	$	474	$	288	$	18,469
	____________________
	-1	Assured Guaranty’s internal rating.
Amounts Due (To) From Reinsurers	Amounts Due (To) From Reinsurers
	As of December 31, 2014
		Assumed				Ceded				Assumed				Ceded
		Premium, net				Premium, net				Expected				Expected
		of Commissions				of Commissions				Loss and LAE				Loss and LAE
		(in millions)
	American Overseas Reinsurance Company Limited (f/k/a Ram Re)	$	—			$	(8	)		$	—			$	11
	Tokio	—				(13		)		—				46
	Radian Asset	—				(13		)		—				19
	Syncora Guarantee Inc.	—				(29		)		—				4
	Mitsui Sumitomo Insurance Co. Ltd.	—				(3		)		—				15
	Swiss Reinsurance Co.	—				(3		)		—				6
	Ambac	43				—				(19		)		—
	National Public Finance Guarantee Corporation	7				—				(7		)		—
	MBIA	5				—				(9		)		—
	FGIC	5				—				(3		)		—
	Ambac Assurance Corp. Segregated Account	13				—				(83		)		—
	CIFG	—				—				(6		)		—
	Other	(2		)		(23		)		—				—
	Total	$	71			$	(92	)		$	(127	)		$	101

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Rental Payments	Future Minimum Rental Payments
	Year	(in millions)
	2015	$	8
	2016	8
	2017	8
	2018	8
	2019	8
	Thereafter	52
	Total	$	92

LongTerm_Debt_and_Credit_Facil1

Long-Term Debt and Credit Facilities (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Principal and Carrying Amounts of Debt	Principal and Carrying Amounts of Debt
		As of December 31, 2014						As of December 31, 2013
		Principal			Carrying			Principal			Carrying
					Value						Value
		(in millions)
	AGUS:
	7.0% Senior Notes	$	200		$	198		$	200		$	198
	5.0% Senior Notes	500			499			—			—
	Series A Enhanced Junior Subordinated Debentures	150			150			150			150
	Total AGUS	850			847			350			348
	AGMH:
	67/8% QUIBS	100			68			100			68
	6.25% Notes	230			139			230			138
	5.60% Notes	100			55			100			55
	Junior Subordinated Debentures	300			175			300			169
	Total AGMH	730			437			730			430
	AGM:
	Notes Payable	16			19			34			38
	Total AGM	16			19			34			38
	Total	$	1,596		$	1,303		$	1,114		$	816
Expected Maturity Schedule of Debt	Expected Maturity Schedule of Debt
	Expected Withdrawal Date		AGUS			AGMH			AGM			Total
			(in millions)
	2015		$	—		$	—		$	7		$	7
	2016		—			—			3			3
	2017		—			—			3			3
	2018		—			—			2			2
	2019		—			—			1			1
	2020-2039		700			—			—			700
	2040-2059		—			—			—			—
	2060-2079		150			300			—			450
	Thereafter		—			430			—			430
	Total		$	850		$	730		$	16		$	1,596
Schedule of Interest Expense	Interest Expense
		Year Ended December 31,
		2014			2013			2012
		(in millions)
	AGUS:
	7.0% Senior Notes	$	13		$	13		$	13
	5.0% Senior Notes	13			—			—
	8.50% Senior Notes	—			—			8
	Series A Enhanced Junior Subordinated Debentures	10			10			10
	Total AGUS	36			23			31
	AGMH:
	67/8% QUIBS	7			7			7
	6.25% Notes	16			16			16
	5.60% Notes	6			6			6
	Junior Subordinated Debentures	25			25			25
	Total AGMH	54			54			54
	AGM:
	Notes Payable	2			5			7
	Total AGM	2			5			7
	Total	$	92		$	82		$	92

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted earnings per share	Computation of Earnings Per Share
		Year Ended December 31,
		2014		2013		2012
		(in millions, except per share amounts)
	Basic EPS:
	Net income (loss) attributable to AGL	$	1,088	$	808	110
	Less: Distributed and undistributed income (loss) available to nonvested shareholders	0		1		0
	Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	1,088	$	807	110
	Basic shares	172.6		186.6		189.2
	Basic EPS	$	6.3	$	4.32	$	0.58
	Diluted EPS:
	Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	1,088	$	807	$	110
	Plus: Re-allocation of undistributed income (loss) available to nonvested shareholders of AGL and subsidiaries	0		0		0
	Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, diluted	$	1,088	$	807	$	110
	Basic shares	172.6		186.6		189.2
	Effect of dilutive securities:
	Options and restricted stock awards	1		1		0.8
	Equity units	—		—		0.7
	Diluted shares	173.6		187.6		190.7
	Diluted EPS	$	6.26	$	4.3	$	0.57
	Potentially dilutive securities excluded from computation of EPS because of antidilutive effect	1.6		2.7		9.9
Schedule of antidilutive securities excluded from computation of earnings per share	Computation of Earnings Per Share
		Year Ended December 31,
		2014		2013		2012
		(in millions, except per share amounts)
	Basic EPS:
	Net income (loss) attributable to AGL	$	1,088	$	808	110
	Less: Distributed and undistributed income (loss) available to nonvested shareholders	0		1		0
	Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	1,088	$	807	110
	Basic shares	172.6		186.6		189.2
	Basic EPS	$	6.3	$	4.32	$	0.58
	Diluted EPS:
	Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic	$	1,088	$	807	$	110
	Plus: Re-allocation of undistributed income (loss) available to nonvested shareholders of AGL and subsidiaries	0		0		0
	Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, diluted	$	1,088	$	807	$	110
	Basic shares	172.6		186.6		189.2
	Effect of dilutive securities:
	Options and restricted stock awards	1		1		0.8
	Equity units	—		—		0.7
	Diluted shares	173.6		187.6		190.7
	Diluted EPS	$	6.26	$	4.3	$	0.57
	Potentially dilutive securities excluded from computation of EPS because of antidilutive effect	1.6		2.7		9.9

Shareholders_Equity_Tables

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Schedule of Stockholders Equity, Share Issuance	Issuance of Shares
		Number of		Price per			Proceeds			Net
		Shares		Share						Proceeds
		(in millions, except share and per share amounts)
	June 1, 2012(1)	13,428,770		$	12.85		$	173		$	173
	____________________
	-1	Relates to the settlement of forward purchase contracts. See Note 17, Long-Term Debt and Credit Facilities.
Schedule of Share Repurchases	Share Repurchases
	Year		Number of Shares Repurchased		Total Payments			Average Price Paid Per Share
					(in millions)
	2015 (through February 26, 2015 on a settlement date basis)		3,581,767		$	92		$	25.63
	2014		24,413,781		$	590		$	24.17
	2013		12,512,759		264			21.12
	2012		2,066,759		24			11.76

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2014
Employee benefit plans [Line Items]
Restricted Stock Award Activity	Restricted Stock Award Activity
	Nonvested Shares		Number of			Weighted
			Shares			Average Grant
						Date Fair Value
						Per Share
	Nonvested at December 31, 2013		48,273			$	23.2
	Granted		47,747			23.98
	Vested		(48,273	)		23.2
	Forfeited		(4,170	)		23.98
	Nonvested at December 31, 2014		43,577			$	23.98
Stock Purchase Plan	Stock Purchase Plan
		Year Ended December 31,
		2014				2013				2012
		(dollars in millions)
	Proceeds from purchase of shares by employees	$	0.9			$	0.9			$	0.6
	Number of shares issued by the Company	43,273				57,980				54,612
	Recorded in share-based compensation, after the effects of DAC	$	0.2			$	0.3			$	0.2
Share-Based Compensation Expense Summary	Share‑Based Compensation Expense Summary
		Year Ended December 31,
		2014				2013				2012
		(in millions)
	Share‑Based Employee Cost:
	Recurring amortization	$	9			$	7			$	6
	Accelerated amortization for retirement eligible employees	0				—				1
	Subtotal	9				7				7
	ESPP	0				0				0
	Total Share‑Based Employee Cost	9				7				7
	Total Share‑Based Directors Cost	1				1				1
	Total Share‑Based Cost	10				8				8
	Less: Share‑based compensation capitalized as DAC	0				—				1
	Share‑based compensation expense	$	10			$	8			$	7
	Income tax benefit	$	2			$	2			$	2
Stock Options [Member]
Employee benefit plans [Line Items]
Schedule of Stock Options	Time Vested Stock Options
		Options for			Weighted				Weighted			Number of	Year of
		Common Shares			Average				Average Grant			Exercisable	Expiration
					Exercise Price				Date Fair Value			Options
									Per Share
	Balance as of December 31, 2013	3,129,251			$	20.97						2,987,088
	Options granted	83,162			21.88				$	10.35			2021
	Options exercised	(409,560	)		17.88
	Options forfeited/expired	—			—
	Balance as of December 31, 2014	2,802,853			$	21.45						2,631,653
Schedule of Weighted Average Assumptions on Option Pricing	Lattice Option Pricing
	Weighted Average Assumptions
		2014			2013				2012
	Dividend yield	2.03	%		2.07		%		2.06	%
	Expected volatility	53.24	%		53.41		%		58.89	%
	Risk free interest rate	2.21	%		1.35		%		1.45	%
	Expected life	6.6 years			6.6 years				6.6 years
	Forfeiture rate	3.5	%		4.5		%		4.5	%
	Weighted average grant date fair value	10.35			$	8.94			8.62
Performance Stock Options [Member]
Employee benefit plans [Line Items]
Schedule of Stock Options	Performance Stock Options
		Options for			Weighted				Weighted			Number of	Year of
		Common Shares			Average				Average Grant			Exercisable	Expiration
					Exercise Price				Date Fair Value			Options
									Per Share
	Balance as of December 31, 2013	365,717			$	17.8						0
	Options granted	—			—				$	—			—
	Options exercised	—			—
	Options forfeited/expired	(118,838	)		17.44
	Balance as of December 31, 2014	246,879			$	17.97						0
Schedule of Weighted Average Assumptions on Option Pricing	Monte Carlo and Lattice Option Pricing
	Weighted Average Assumptions (1)
		2013				2012
	Dividend yield	2.07		%		2.06		%
	Expected volatility	53.5		%		58.89		%
	Risk free interest rate	1.36		%		1.45		%
	Expected life	6.3 years				6.3 years
	Forfeiture rate	4.5		%		4.5		%
	Weighted average grant date fair value	$	8.17			$	7.84
Restricted Stock Units [Member]
Employee benefit plans [Line Items]
Restricted Stock Unit Activity (Excluding Dividend Equivalents)	Restricted Stock Unit Activity
	(Excluding Dividend Equivalents)
	Nonvested Stock Units		Number of			Weighted
			Stock Units			Average Grant
						Date Fair Value
						Per Share
	Nonvested at December 31, 2013		736,409			$	17.63
	Granted		238,976			21.61
	Delivered		(284,082	)		17.13
	Forfeited		—			—
	Nonvested at December 31, 2014		691,303			$	19.23
Performance Restricted Stock Units [Member]
Employee benefit plans [Line Items]
Restricted Stock Unit Activity (Excluding Dividend Equivalents)	Performance Restricted Stock Unit Activity
	Performance Restricted Stock Units		Number of			Weighted
			Performance Share Units			Average Grant
						Date Fair Value
						Per Share
	Nonvested at December 31, 2013		223,410			$	27.79
	Granted		203,287			25.17
	Delivered		—			—
	Forfeited		(3,395	)		27.35
	Nonvested at December 31, 2014		423,302			$	26.72

Other_Comprehensive_Income_Tab

Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Changes in Accumulated Other Comprehensive Income by Component	Changes in Accumulated Other Comprehensive Income by Component
	Year Ended December 31, 2014
		Net Unrealized			Net Unrealized			Cumulative			Cash Flow Hedge			Total Accumulated
		Gains (Losses) on			Gains (Losses) on			Translation						Other
		Investments with no Other-Than-Temporary Impairment			Investments with Other-Than-Temporary Impairment			Adjustment						Comprehensive
														Income
		(in millions)
	Balance, December 31, 2013	$	178		$	(24	)	$	(3	)	$	9		$	160
	Other comprehensive income (loss) before reclassifications	196			(20		)	(7		)	—			169
	Amounts reclassified from AOCI to:
	Net realized investment gains (losses)	(12		)	74			—			—			62
	Interest expense	—			—			—			0			0
	Total before tax	(12		)	74			—			0			62
	Tax (provision) benefit	5			(26		)	—			0			(21		)
	Total amount reclassified from AOCI, net of tax	(7		)	48			—			0			41
	Net current period other comprehensive income (loss)	189			28			(7		)	0			210
	Balance, December 31, 2014	$	367		$	4		$	(10	)	$	9		$	370
	Changes in Accumulated Other Comprehensive Income by Component
	Year Ended December 31, 2013
		Net Unrealized			Net Unrealized			Cumulative			Cash Flow Hedge			Total Accumulated
		Gains (Losses) on			Gains (Losses) on			Translation						Other
		Investments with no Other-Than-Temporary Impairment			Investments with Other-Than-Temporary Impairment			Adjustment						Comprehensive
														Income
		(in millions)
	Balance, December 31, 2012	$	517		$	(5	)	$	(6	)	$	9		$	515
	Other comprehensive income (loss) before reclassifications	(309		)	(35		)	3			—			(341		)
	Amounts reclassified from AOCI to:
	Net realized investment gains (losses)	(43		)	24			—			—			(19		)
	Interest expense	—			—			—			(1		)	(1		)
	Total before tax	(43		)	24			—			(1		)	(20		)
	Tax (provision) benefit	13			(8		)	—			1			6
	Total amount reclassified from AOCI, net of tax	(30		)	16			—			0			(14		)
	Net current period other comprehensive income (loss)	(339		)	(19		)	3			0			(355		)
	Balance, December 31, 2013	$	178		$	(24	)	$	(3	)	$	9		$	160
	Changes in Accumulated Other Comprehensive Income by Component
	Year Ended December 31, 2012
		Net Unrealized			Net Unrealized			Cumulative			Cash Flow Hedge			Total Accumulated
		Gains (Losses) on			Gains (Losses) on			Translation						Other
		Investments with no Other-Than-Temporary Impairment			Investments with Other-Than-Temporary Impairment			Adjustment						Comprehensive
														Income
		(in millions)
	Balance, December 31, 2011	$	365		$	2		$	(8	)	$	9		$	368
	Other comprehensive income (loss)	152			(7		)	2			0			147
	Balance, December 31, 2012	$	517		$	(5	)	$	(6	)	$	9		$	515

Subsidiary_Information_Tables

Subsidiary Information (Tables)	12 Months Ended
	Dec. 31, 2014
Subsidiary Information [abstract]
Condensed Consolidating Balance Sheet	CONDENSED CONSOLIDATING BALANCE SHEET
	AS OF DECEMBER 31, 2014
	(in millions)
		Assured			AGUS			AGMH			Other			Consolidating			Assured
		Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
		(Parent)															(Consolidated)
	ASSETS
	Total investment portfolio and cash	$	126		$	204		$	47		$	11,382		$	(300	)	$	11,459
	Investment in subsidiaries	5,612			5,072			3,965			339			(14,988		)	—
	Premiums receivable, net of commissions payable	—			—			—			864			(135		)	729
	Ceded unearned premium reserve	—			—			—			1,469			(1,088		)	381
	Deferred acquisition costs	—			—			—			186			(65		)	121
	Reinsurance recoverable on unpaid losses	—			—			—			338			(260		)	78
	Credit derivative assets	—			—			—			277			(209		)	68
	Deferred tax asset, net	—			54			—			295			(89		)	260
	Intercompany receivable	—			—			—			90			(90		)	—
	Financial guaranty variable interest entities’ assets, at fair value	—			—			—			1,402			—			1,402
	Other	27			77			27			538			(242		)	427
	TOTAL ASSETS	$	5,765		$	5,407		$	4,039		$	17,180		$	(17,466	)	$	14,925
	LIABILITIES AND SHAREHOLDERS’ EQUITY
	Unearned premium reserves	$	—		$	—		$	—		$	5,328		$	(1,067	)	$	4,261
	Loss and LAE reserve	—			—			—			1,066			(267		)	799
	Long-term debt	—			847			437			19			—			1,303
	Intercompany payable	—			90			—			300			(390		)	—
	Credit derivative liabilities	—			—			—			1,172			(209		)	963
	Deferred tax liabilities, net	—			—			94			—			(94		)	—
	Financial guaranty variable interest entities’ liabilities, at fair value	—			—			—			1,419			—			1,419
	Other	7			9			16			764			(374		)	422
	TOTAL LIABILITIES	7			946			547			10,068			(2,401		)	9,167
	TOTAL SHAREHOLDERS’ EQUITY ATTRIBUTABLE TO ASSURED GUARANTY LTD.	5,758			4,461			3,492			6,773			(14,726		)	5,758
	Noncontrolling interest	—			—			—			339			(339		)	—
	TOTAL SHAREHOLDERS’ EQUITY	5,758			4,461			3,492			7,112			(15,065		)	5,758
	TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$	5,765		$	5,407		$	4,039		$	17,180		$	(17,466	)	$	14,925
	CONDENSED CONSOLIDATING BALANCE SHEET
	AS OF DECEMBER 31, 2013
	(in millions)
		Assured			AGUS			AGMH			Other			Consolidating			Assured
		Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
		(Parent)															(Consolidated)
	ASSETS
	Total investment portfolio and cash	$	33		$	186		$	42		$	11,008		$	(300	)	$	10,969
	Investment in subsidiaries	5,066			4,191			3,574			289			(13,120		)	—
	Premiums receivable, net of commissions payable	—			—			—			1,025			(149		)	876
	Ceded unearned premium reserve	—			—			—			1,598			(1,146		)	452
	Deferred acquisition costs	—			—			—			198			(74		)	124
	Reinsurance recoverable on unpaid losses	—			—			—			170			(134		)	36
	Credit derivative assets	—			—			—			482			(388		)	94
	Deferred tax asset, net	—			97			—			681			(90		)	688
	Intercompany receivable	—			—			—			90			(90		)	—
	Financial guaranty variable interest entities’ assets, at fair value	—			—			—			2,565			—			2,565
	Other	23			17			31			638			(226		)	483
	TOTAL ASSETS	$	5,122		$	4,491		$	3,647		$	18,744		$	(15,717	)	$	16,287
	LIABILITIES AND SHAREHOLDERS’ EQUITY
	Unearned premium reserves	$	—		$	—		$	—		$	5,720		$	(1,125	)	$	4,595
	Loss and LAE reserve	—			—			—			733			(141		)	592
	Long-term debt	—			348			430			38			—			816
	Intercompany payable	—			90			—			300			(390		)	—
	Credit derivative liabilities	—			—			—			2,175			(388		)	1,787
	Deferred tax liabilities, net	—			—			95			—			(95		)	—
	Financial guaranty variable interest entities’ liabilities, at fair value	—			—			—			2,871			—			2,871
	Other	7			7			16			853			(372		)	511
	TOTAL LIABILITIES	7			445			541			12,690			(2,511		)	11,172
	TOTAL SHAREHOLDERS’ EQUITY ATTRIBUTABLE TO ASSURED GUARANTY LTD.	5,115			4,046			3,106			5,765			(12,917		)	5,115
	Noncontrolling interest	—			—			—			289			(289		)	—
TOTAL SHAREHOLDERS’ EQUITY	5,115			4,046			3,106			6,054			(13,206		)	5,115
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$	5,122		$	4,491		$	3,647		$	18,744		$	(15,717	)	$	16,287
Condensed Consolidating Statement of Operations and Comprehensive Income	CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS
	AND COMPREHENSIVE INCOME
	FOR THE YEAR ENDED DECEMBER 31, 2014
	(in millions)
		Assured			AGUS			AGMH			Other			Consolidating			Assured
		Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
		(Parent)															(Consolidated)
	REVENUES
	Net earned premiums	$	—		$	—		$	—		$	566		$	4		$	570
	Net investment income	0			0			1			412			(10		)	403
	Net realized investment gains (losses)	0			0			0			(58		)	(2		)	(60		)
	Net change in fair value of credit derivatives:
	Realized gains (losses) and other settlements	—			—			—			23			—			23
	Net unrealized gains (losses)	—			—			—			800			—			800
	Net change in fair value of credit derivatives	—			—			—			823			—			823
	Other	0			0			—			259			(1		)	258
	TOTAL REVENUES	0			0			1			2,002			(9		)	1,994
	EXPENSES
	Loss and LAE	—			—			—			122			4			126
	Amortization of deferred acquisition costs	—			—			—			33			(8		)	25
	Interest expense	—			40			54			16			(18		)	92
	Other operating expenses	31			1			1			195			(8		)	220
	TOTAL EXPENSES	31			41			55			366			(30		)	463
	INCOME (LOSS) BEFORE INCOME TAXES AND EQUITY IN NET EARNINGS OF SUBSIDIARIES	(31		)	(41		)	(54		)	1,636			21			1,531
	Total (provision) benefit for income taxes	—			14			19			(469		)	(7		)	(443		)
	Equity in net earnings of subsidiaries	$	1,119		$	983		$	513		$	32		$	(2,647	)	—
	NET INCOME (LOSS)	1,088			956			478			1,199			(2,633		)	1,088
	Less: noncontrolling interest	—			—			—			32			(32		)	—
	NET INCOME (LOSS) ATTRIBUTABLE TO ASSURED GUARANTY LTD.	$	1,088		$	956		$	478		$	1,167		$	(2,601	)	$	1,088
	COMPREHENSIVE INCOME (LOSS)	$	1,298		$	1,114		$	577		$	1,570		$	(3,261	)	$	1,298
	CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS
	AND COMPREHENSIVE INCOME
	FOR THE YEAR ENDED DECEMBER 31, 2013
	(in millions)
		Assured			AGUS			AGMH			Other			Consolidating			Assured
		Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
		(Parent)															(Consolidated)
	REVENUES
	Net earned premiums	$	—		$	—		$	—		$	740		$	12		$	752
	Net investment income	0			0			1			408			(16		)	393
	Net realized investment gains (losses)	0			0			0			87			(35		)	52
	Net change in fair value of credit derivatives:
	Realized gains (losses) and other settlements	—			—			—			(42		)	—			(42		)
	Net unrealized gains (losses)	—			—			—			107			—			107
	Net change in fair value of credit derivatives	—			—			—			65			—			65
	Other	—			—			—			348			(2		)	346
	TOTAL REVENUES	0			0			1			1,648			(41		)	1,608
	EXPENSES
	Loss and LAE	—			—			—			144			10			154
	Amortization of deferred acquisition costs	—			—			—			12			0			12
	Interest expense	—			28			54			20			(20		)	82
	Other operating expenses	22			1			1			199			(5		)	218
	TOTAL EXPENSES	22			29			55			375			(15		)	466
	INCOME (LOSS) BEFORE INCOME TAXES AND EQUITY IN NET EARNINGS OF SUBSIDIARIES	(22		)	(29		)	(54		)	1,273			(26		)	1,142
	Total (provision) benefit for income taxes	—			9			17			(387		)	27			(334		)
	Equity in net earnings of subsidiaries	830			768			701			19			(2,318		)	—
	NET INCOME (LOSS)	808			748			664			905			(2,317		)	808
	Less: noncontrolling interest	—			—			—			19			(19		)	—
	NET INCOME (LOSS) ATTRIBUTABLE TO ASSURED GUARANTY LTD.	$	808		$	748		$	664		$	886		$	(2,298	)	$	808
	COMPREHENSIVE INCOME (LOSS)	$	453		$	522		$	515		$	309		$	(1,346	)	$	453
	CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS
	AND COMPREHENSIVE INCOME
	FOR THE YEAR ENDED DECEMBER 31, 2012
	(in millions)
	Assured			AGUS			AGMH			Other			Consolidating			Assured
	Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
	(Parent)															(Consolidated)
REVENUES
Net earned premiums	$	—		$	—		$	—		$	833		$	20		$	853
Net investment income	0			—			1			422			(19		)	404
Net realized investment gains (losses)	—			—			—			1			—			1
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements	—			—			—			(108		)	—			(108		)
Net unrealized gains (losses)	—			—			—			(477		)	—			(477		)
Net change in fair value of credit derivatives	—			—			—			(585		)	—			(585		)
Other	—			—			—			284			(3		)	281
TOTAL REVENUES	0			—			1			955			(2		)	954
EXPENSES
Loss and LAE	—			—			—			509			(5		)	504
Amortization of deferred acquisition costs	—			—			—			28			(14		)	14
Interest expense	—			35			54			22			(19		)	92
Other operating expenses	21			2			1			194			(6		)	212
TOTAL EXPENSES	21			37			55			753			(44		)	822
INCOME (LOSS) BEFORE INCOME TAXES AND EQUITY IN NET EARNINGS OF SUBSIDIARIES	(21		)	(37		)	(54		)	202			42			132
Total (provision) benefit for income taxes	—			13			19			(38		)	(16		)	(22		)
Equity in net earnings of subsidiaries	131			177			424			153			(885		)	—
NET INCOME (LOSS)	$	110		$	153		$	389		$	317		$	(859	)	$	110
COMPREHENSIVE INCOME (LOSS)	$	257		$	266		$	465		$	577		$	(1,308	)	$	257
Condensed Consolidating Statement of Cash Flows	CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
	FOR THE YEAR ENDED DECEMBER 31, 2014
	(in millions)
		Assured			AGUS			AGMH			Other			Consolidating			Assured
		Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
		(Parent)															(Consolidated)
	Net cash flows provided by (used in) operating activities	$	758		$	223		$	144		$	663		$	(1,211	)	$	577
	Cash flows from investing activities
	Fixed-maturity securities:
	Purchases	—			(540		)	(8		)	(2,253		)	—			(2,801		)
	Sales	—			464			10			777			—			1,251
	Maturities	—			6			1			870			—			877
	Sales (purchases) of short-term investments, net	(93		)	(15		)	(3		)	269			—			158
	Net proceeds from financial guaranty variable entities’ assets										408			—			408
	Intercompany debt	—			—			—			—			—			—
	Investment in subsidiary	—			—			50			—			(50		)	—
	Other	—			—			—			11			—			11
	Net cash flows provided by (used in) investing activities	(93		)	(85		)	50			82			(50		)	(96		)
	Cash flows from financing activities
	Return of capital	—			—			—			(50		)	50			—
	Capital contribution from parent	—			—			—			—			—			—
	Dividends paid	(76		)	(700		)	(190		)	(321		)	1,211			(76		)
	Repurchases of common stock	(590		)	—			—			—			—			(590		)
	Share activity under option and incentive plans	1			—			—			—			—			1
	Net paydowns of financial guaranty variable entities’ liabilities	—			—			—			(396		)	—			(396		)
	Net proceeds from issuance of long-term debt	—			495			—			—			—			495
	Payment of long-term debt	—			—			—			(19		)	—			(19		)
	Intercompany debt	—			—			—			—			—			—
	Net cash flows provided by (used in) financing activities	(665		)	(205		)	(190		)	(786		)	1,261			(585		)
	Effect of exchange rate changes	—			—			—			(5		)	—			(5		)
	Increase (decrease) in cash	—			(67		)	4			(46		)	—			(109		)
	Cash at beginning of period	0			67			0			117			—			184
	Cash at end of period	$	0		$	0		$	4		$	71		$	—		$	75
	CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
	FOR THE YEAR ENDED DECEMBER 31, 2013
	(in millions)
		Assured			AGUS			AGMH			Other			Consolidating			Assured
		Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
		(Parent)															(Consolidated)
	Net cash flows provided by (used in) operating activities	$	128		$	178		$	133		$	347		$	(542	)	$	244
	Cash flows from investing activities
	Fixed-maturity securities:
	Purchases	—			(93		)	(26		)	(1,832		)	65			(1,886		)
	Sales	176			1			25			892			(65		)	1,029
	Maturities	29			3			2			849			—			883
	Sales (purchases) of short-term investments, net	7			(28		)	(15		)	(51		)	—			(87		)
	Net proceeds from financial guaranty variable entities’ assets	—			—			—			663			—			663
	Intercompany debt	—			—			—			7			(7		)	—
	Investment in subsidiary	—			0			49			—			(49		)	—
	Other	—			—			—			79			—			79
	Net cash flows provided by (used in) investing activities	212			(117		)	35			607			(56		)	681
	Cash flows from financing activities																—
	Return of capital	—			—			—			(50		)	50			—
	Capital contribution from parent	—			—			—			1			(1		)	—
	Dividends paid	(75		)	—			(168		)	(374		)	542			(75		)
	Repurchases of common stock	(264		)	—			—			—			—			(264		)
	Share activity under option and incentive plans	(1		)	—			—			—			—			(1		)
	Net paydowns of financial guaranty variable entities’ liabilities	—			—			—			(511		)	—			(511		)
	Payment of long-term debt	—			—			—			(27		)	—			(27		)
	Intercompany debt	—			(7		)	—			—			7			—
	Net cash flows provided by (used in) financing activities	(340		)	(7		)	(168		)	(961		)	598			(878		)
	Effect of exchange rate changes	—			—			—			(1		)	—			(1		)
	Increase (decrease) in cash	0			54			—			(8		)	—			46
	Cash at beginning of period	—			13			0			125			—			138
Cash at end of period	$	0		$	67		$	0		$	117		$	—		$	184
CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS
FOR THE YEAR ENDED DECEMBER 31, 2012
(in millions)
	Assured			AGUS			AGMH			Other			Consolidating			Assured
	Guaranty Ltd.			(Issuer)			(Issuer)			Entities			Adjustments			Guaranty Ltd.
	(Parent)															(Consolidated)
Net cash flows provided by (used in) operating activities	$	138		$	6		$	20		$	5		$	(334	)	$	(165	)
Cash flows from investing activities
Fixed-maturity securities:
Purchases	(211		)	(1		)	(13		)	(1,424		)	—			(1,649		)
Sales	—			—			13			899			—			912
Maturities	3			—			6			1,096			—			1,105
Sales (purchases) of short-term investments, net	(7		)	27			26			(17		)	—			29
Net proceeds from financial guaranty variable entities’ assets	—			—			—			545			—			545
Acquisition of MAC	—			(91		)	—			—			—			(91		)
Intercompany debt	—			—			—			(173		)	173			—
Investment in subsidiary	—			—			46			—			(46		)	—
Other	—			—			—			92			—			92
Net cash flows provided by (used in) investing activities	(215		)	(65		)	78			1,018			127			943
Cash flows from financing activities
Issuance of common stock	173			—			—			—			—			173
Return of capital	—			—			—			(50		)	50			—
Capital contribution from parent	—			—			—			4			(4		)	—
Dividends paid	(69		)	—			(98		)	(236		)	334			(69		)
Repurchases of common stock	(24		)	—			—			—			—			(24		)
Share activity under option and incentive plans	(3		)	—			—			—			—			(3		)
Net paydowns of financial guaranty variable entities’ liabilities	—			—			—			(724		)	—			(724		)
Payment of long-term debt	—			(173		)	—			(36		)	—			(209		)
Intercompany debt	—			173			—			—			(173		)	—
Net cash flows provided by (used in) financing activities	77			—			(98		)	(1,042		)	207			(856		)
Effect of exchange rate changes	—			—			—			1			—			1
Increase (decrease) in cash	—			(59		)	—			(18		)	—			(77		)
Cash at beginning of period	—			72			0			143			—			215
Cash at end of period	$	—		$	13		$	0		$	125		$	—		$	138

Quarterly_Financial_Informatio1

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Information	A summary of selected quarterly information follows:
	2014		First			Second			Third			Fourth			Full
			Quarter			Quarter			Quarter			Quarter			Year
			(dollars in millions, except per share data)
	Revenues
	Net earned premiums		$	132		$	136		$	144		$	158		$	570
	Net investment income		103			96			102			102			403
	Net realized investment gains (losses)		2			(8		)	(19		)	(35		)	(60		)
	Net change in fair value of credit derivatives		(211		)	103			255			676			823
	Fair value gains (losses) on CCS		(9		)	(6		)	4			0			(11		)
	Fair value gains (losses) on FG VIEs		157			25			50			23			255
	Other income (loss)		21			7			(11		)	(3		)	14
	Expenses
	Loss and LAE		41			57			(44		)	72			126
	Amortization of DAC		5			3			4			13			25
	Interest expense		20			20			27			25			92
	Other operating expenses		60			55			50			55			220
	Income (loss) before provision for income taxes		69			218			488			756			1,531
	Provision (benefit) for income taxes		27			59			133			224			443
	Net income (loss)		42			159			355			532			1,088
	Earnings (loss) per share(1):
	Basic		$	0.23		$	0.89		$	2.1		$	3.3		$	6.3
	Diluted		$	0.23		$	0.89		$	2.09		$	3.28		$	6.26
	Dividends per share		$	0.11		$	0.11		$	0.11		$	0.11		$	0.44
	2013		First			Second			Third			Fourth			Full
			Quarter			Quarter			Quarter			Quarter			Year
			(dollars in millions, except per share data)
	Revenues
	Net earned premiums		$	248		$	163		$	159		$	182		$	752
	Net investment income		94			93			99			107			393
	Net realized investment gains (losses)		28			2			(7		)	29			52
	Net change in fair value of credit derivatives		(592		)	74			354			229			65
	Fair value gains (losses) on CCS		(10		)	(3		)	9			14			10
	Fair value gains (losses) on FG VIEs		70			143			40			93			346
	Other income (loss)		(14		)	(7		)	16			(5		)	(10		)
	Expenses
	Loss and LAE		(48		)	62			55			85			154
	Amortization of DAC		3			1			4			4			12
	Interest expense		21			21			21			19			82
	Other operating expenses		60			52			54			52			218
	Income (loss) before provision for income taxes		(212		)	329			536			489			1,142
	Provision (benefit) for income taxes		(68		)	110			152			140			334
	Net income (loss)		(144		)	219			384			349			808
	Earnings (loss) per share(1):
	Basic		$	(0.74	)	$	1.17		$	2.1		$	1.91		$	4.32
	Diluted		$	(0.74	)	$	1.16		$	2.09		$	1.9		$	4.3
	Dividends per share		$	0.1		$	0.1		$	0.1		$	0.1		$	0.4
	____________________
	-1	Per share amounts for the quarters and the full years have each been calculated separately. Accordingly, quarterly amounts may not sum up to the annual amounts because of differences in the average common shares outstanding during each period and, with regard to diluted per share amounts only, because of the inclusion of the effect of potentially dilutive securities only in the periods in which such effect would have been dilutive.

Business_and_Basis_of_Presenta2

Business and Basis of Presentation (Details) (USD $)	0 Months Ended	12 Months Ended
	Dec. 22, 2014	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013
			Company
Business Acquisition [Line Items]
Net par outstanding			$609,622,000,000	$690,535,000,000
Number of holding companies having public debt outstanding			2
Radian [Member]
Business Acquisition [Line Items]
Expected payments to acquire business in first half of 2015	810,000,000
MAC [Member]
Business Acquisition [Line Items]
Cash paid to acquire entity		91,000,000
Allocation of purchase price to intangible assets other than goodwill		16,000,000
Radian [Member]
Business Acquisition [Line Items]
Qualified statutory capital			1,300,000,000
Public Finance [Member]
Business Acquisition [Line Items]
Net par outstanding			553,612,000,000	610,011,000,000
Public Finance [Member] | Radian [Member]
Business Acquisition [Line Items]
Net par outstanding			10,000,000,000
Structured Finance [Member]
Business Acquisition [Line Items]
Net par outstanding			56,010,000,000	80,524,000,000
Structured Finance [Member] | Radian [Member]
Business Acquisition [Line Items]
Net par outstanding			$8,000,000,000

Outstanding_Exposure_Debt_Serv

Outstanding Exposure - Debt Service Outstanding (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	$646,722	$737,380
Net Debt Service Outstanding	609,622	690,535
Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	587,245	650,924
Net Debt Service Outstanding	553,612	610,011
Structured Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	59,477	86,456
Net Debt Service Outstanding	$56,010	$80,524

Outstanding_Exposure_Financial

Outstanding Exposure - Financial Guaranty Portfolio by Internal Rating (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	$403,729,000,000	[1]	$459,107,000,000	[2]
% of total net par outstanding	100.00%	[1]	100.00%	[2]
United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	363,294,000,000
Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	40,435,000,000
AAA [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	30,143,000,000		48,015,000,000
% of total net par outstanding	7.50%		10.50%
AA [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	101,965,000,000		117,933,000,000
% of total net par outstanding	25.30%		25.70%
A [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	186,875,000,000		205,616,000,000
% of total net par outstanding	46.30%		44.80%
BBB [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	66,499,000,000		65,005,000,000
% of total net par outstanding	16.40%		14.10%
BIG [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	18,247,000,000		22,538,000,000
% of total net par outstanding	4.50%		4.90%
Loss mitigation bonds	1,300,000,000	[2]	1,200,000,000	[2]
Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	353,482,000,000		386,179,000,000
Public Finance [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	322,123,000,000	[1]	352,181,000,000	[2]
% of total net par outstanding	100.00%	[1]	100.00%	[2]
Public Finance [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	31,359,000,000	[1]	33,998,000,000	[2]
% of total net par outstanding	100.00%	[1]	100.00%	[2]
Public Finance [Member] | AAA [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	4,082,000,000		4,998,000,000
% of total net par outstanding	1.30%		1.40%
Public Finance [Member] | AAA [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	615,000,000		1,016,000,000
% of total net par outstanding	2.00%		3.00%
Public Finance [Member] | AA [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	90,464,000,000		107,503,000,000
% of total net par outstanding	28.10%		30.50%
Public Finance [Member] | AA [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	2,785,000,000		422,000,000
% of total net par outstanding	8.90%		1.20%
Public Finance [Member] | A [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	176,298,000,000		192,841,000,000
% of total net par outstanding	54.70%		54.80%
Public Finance [Member] | A [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	7,192,000,000		9,453,000,000
% of total net par outstanding	22.90%		27.90%
Public Finance [Member] | BBB [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	43,429,000,000		37,745,000,000
% of total net par outstanding	13.50%		10.70%
Public Finance [Member] | BBB [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	19,363,000,000		21,499,000,000
% of total net par outstanding	61.70%		63.20%
Public Finance [Member] | BIG [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	7,850,000,000		9,094,000,000
% of total net par outstanding	2.40%		2.60%
Public Finance [Member] | BIG [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,404,000,000		1,608,000,000
% of total net par outstanding	4.50%		4.70%
Structured Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	50,247,000,000		72,928,000,000
Structured Finance [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	41,171,000,000	[1]	58,907,000,000	[2]
% of total net par outstanding	100.00%	[1]	100.00%	[2]
Structured Finance [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	9,076,000,000	[1]	14,021,000,000	[2]
% of total net par outstanding	100.00%	[1]	100.00%	[2]
Structured Finance [Member] | AAA [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	20,037,000,000		32,317,000,000
% of total net par outstanding	48.70%		54.90%
Structured Finance [Member] | AAA [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	5,409,000,000		9,684,000,000
% of total net par outstanding	59.60%		69.10%
Structured Finance [Member] | AA [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	8,213,000,000		9,431,000,000
% of total net par outstanding	19.90%		16.00%
Structured Finance [Member] | AA [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	503,000,000		577,000,000
% of total net par outstanding	5.50%		4.10%
Structured Finance [Member] | A [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	2,940,000,000		2,580,000,000
% of total net par outstanding	7.10%		4.40%
Structured Finance [Member] | A [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	445,000,000		742,000,000
% of total net par outstanding	4.90%		5.30%
Structured Finance [Member] | BBB [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,795,000,000		3,815,000,000
% of total net par outstanding	4.40%		6.40%
Structured Finance [Member] | BBB [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,912,000,000		1,946,000,000
% of total net par outstanding	21.10%		13.90%
Structured Finance [Member] | BIG [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	8,186,000,000		10,764,000,000
% of total net par outstanding	19.90%		18.30%
Structured Finance [Member] | BIG [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	$807,000,000		$1,072,000,000
% of total net par outstanding	8.90%		7.60%
[1]	Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.
[2]	Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of December 31, 2013, which are primarily in the BIG category.

Outstanding_Exposure_Financial1

Outstanding Exposure - Financial Guaranty Portfolio by Asset Class (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	$426,704		$487,895
Ceded Par Amount	22,975	[1]	28,788
Net Par Outstanding (excluding loss mitigation bonds)	403,729	[2]	459,107	[3]
Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	373,360		409,890
Ceded Par Amount	19,878		23,711
Net Par Outstanding (excluding loss mitigation bonds)	353,482		386,179
Structured Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	53,344		78,005
Ceded Par Amount	3,097		5,077
Net Par Outstanding (excluding loss mitigation bonds)	50,247		72,928
United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding (excluding loss mitigation bonds)	363,294
United States [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	334,906		367,616
Ceded Par Amount	12,783		15,435
Net Par Outstanding (excluding loss mitigation bonds)	322,123	[2]	352,181	[3]
United States [Member] | Public Finance [Member] | General obligation [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	144,714		160,751
Ceded Par Amount	4,438		5,474
Net Par Outstanding (excluding loss mitigation bonds)	140,276		155,277
United States [Member] | Public Finance [Member] | Tax backed [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	65,600		70,552
Ceded Par Amount	3,075		3,728
Net Par Outstanding (excluding loss mitigation bonds)	62,525		66,824
United States [Member] | Public Finance [Member] | Municipal utilities [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	53,471		57,893
Ceded Par Amount	1,381		1,569
Net Par Outstanding (excluding loss mitigation bonds)	52,090		56,324
United States [Member] | Public Finance [Member] | Transportation [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	28,914		32,514
Ceded Par Amount	1,091		1,684
Net Par Outstanding (excluding loss mitigation bonds)	27,823		30,830
United States [Member] | Public Finance [Member] | Healthcare [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	16,225		17,663
Ceded Par Amount	1,377		1,531
Net Par Outstanding (excluding loss mitigation bonds)	14,848		16,132
United States [Member] | Public Finance [Member] | Higher education [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	13,485		14,470
Ceded Par Amount	386		399
Net Par Outstanding (excluding loss mitigation bonds)	13,099		14,071
United States [Member] | Public Finance [Member] | Infrastructure finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	5,098		5,014
Ceded Par Amount	917		900
Net Par Outstanding (excluding loss mitigation bonds)	4,181		4,114
United States [Member] | Public Finance [Member] | Housing [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	2,880		3,518
Ceded Par Amount	101		132
Net Par Outstanding (excluding loss mitigation bonds)	2,779		3,386
United States [Member] | Public Finance [Member] | Investor-owned utilities [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	944		992
Ceded Par Amount	0		1
Net Par Outstanding (excluding loss mitigation bonds)	944		991
United States [Member] | Public Finance [Member] | Other public/structured finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	3,575		4,249
Ceded Par Amount	17		17
Net Par Outstanding (excluding loss mitigation bonds)	3,558		4,232
United States [Member] | Structured Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	43,288		62,591
Ceded Par Amount	2,117		3,684
Net Par Outstanding (excluding loss mitigation bonds)	41,171	[2]	58,907	[3]
United States [Member] | Structured Finance [Member] | Other public/structured finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	858		2,067
Ceded Par Amount	144		1,080
Net Par Outstanding (excluding loss mitigation bonds)	714		987
United States [Member] | Structured Finance [Member] | Pooled corporate obligations [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	21,791		32,955
Ceded Par Amount	1,145		1,630
Net Par Outstanding (excluding loss mitigation bonds)	20,646		31,325
United States [Member] | Structured Finance [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	10,109		14,542
Ceded Par Amount	692		821
Net Par Outstanding (excluding loss mitigation bonds)	9,417		13,721
United States [Member] | Structured Finance [Member] | Commercial mortgage-backed securities (CMBS) and other commercial real estate related exposures [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	1,979		3,990
Ceded Par Amount	22		38
Net Par Outstanding (excluding loss mitigation bonds)	1,957		3,952
United States [Member] | Structured Finance [Member] | Insurance securitizations [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	3,480		3,082
Ceded Par Amount	47		47
Net Par Outstanding (excluding loss mitigation bonds)	3,433		3,035
United States [Member] | Structured Finance [Member] | Financial product [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	2,276		2,709
Ceded Par Amount	0		0
Net Par Outstanding (excluding loss mitigation bonds)	2,276		2,709
United States [Member] | Structured Finance [Member] | Consumer receivables [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	2,157		2,257
Ceded Par Amount	58		59
Net Par Outstanding (excluding loss mitigation bonds)	2,099		2,198
United States [Member] | Structured Finance [Member] | Commercial receivables [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	567		918
Ceded Par Amount	7		7
Net Par Outstanding (excluding loss mitigation bonds)	560		911
United States [Member] | Structured Finance [Member] | Structured credit [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	71		71
Ceded Par Amount	2		2
Net Par Outstanding (excluding loss mitigation bonds)	69		69
Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding (excluding loss mitigation bonds)	40,435
Non United States [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	38,454		42,274
Ceded Par Amount	7,095		8,276
Net Par Outstanding (excluding loss mitigation bonds)	31,359	[2]	33,998	[3]
Non United States [Member] | Public Finance [Member] | Infrastructure finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	15,091		17,373
Ceded Par Amount	2,283		2,670
Net Par Outstanding (excluding loss mitigation bonds)	12,808		14,703
Non United States [Member] | Public Finance [Member] | Regulated utilities [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	14,582		15,502
Ceded Par Amount	3,668		4,297
Net Par Outstanding (excluding loss mitigation bonds)	10,914		11,205
Non United States [Member] | Public Finance [Member] | Pooled infrastructure [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	2,565		2,754
Ceded Par Amount	145		234
Net Par Outstanding (excluding loss mitigation bonds)	2,420		2,520
Non United States [Member] | Public Finance [Member] | Other public/structured finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	6,216		6,645
Ceded Par Amount	999		1,075
Net Par Outstanding (excluding loss mitigation bonds)	5,217		5,570
Non United States [Member] | Structured Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	10,056		15,414
Ceded Par Amount	980		1,393
Net Par Outstanding (excluding loss mitigation bonds)	9,076	[2]	14,021	[3]
Non United States [Member] | Structured Finance [Member] | Other public/structured finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	750		403
Ceded Par Amount	25		25
Net Par Outstanding (excluding loss mitigation bonds)	725		378
Non United States [Member] | Structured Finance [Member] | Pooled corporate obligations [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	7,439		12,232
Ceded Par Amount	835		1,174
Net Par Outstanding (excluding loss mitigation bonds)	6,604		11,058
Non United States [Member] | Structured Finance [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	893		1,296
Ceded Par Amount	99		150
Net Par Outstanding (excluding loss mitigation bonds)	794		1,146
Non United States [Member] | Structured Finance [Member] | Commercial receivables [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	965		1,286
Ceded Par Amount	21		23
Net Par Outstanding (excluding loss mitigation bonds)	944		1,263
Non United States [Member] | Structured Finance [Member] | Structured credit [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	9		197
Ceded Par Amount	0		21
Net Par Outstanding (excluding loss mitigation bonds)	$9		$176
[1]	Includes par related to insured credit derivatives.
[2]	Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.
[3]	Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of December 31, 2013, which are primarily in the BIG category.

Outstanding_Exposure_Expected_

Outstanding Exposure - Expected Amortization of Net Par Outstanding (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Expected Amortization of Net Par Outstanding [Abstract]
0 to 5 years	$134,913
5 to 10 years	80,733
10 to 15 years	70,228
15 to 20 years	53,551
20 years and above	64,304
Net Par Outstanding (excluding loss mitigation bonds)	403,729	[1]	459,107	[2]
Public Finance [Member]
Expected Amortization of Net Par Outstanding [Abstract]
0 to 5 years	98,431
5 to 10 years	75,279
10 to 15 years	67,354
15 to 20 years	51,139
20 years and above	61,279
Net Par Outstanding (excluding loss mitigation bonds)	353,482		386,179
Structured Finance [Member]
Expected Amortization of Net Par Outstanding [Abstract]
0 to 5 years	36,482
5 to 10 years	5,454
10 to 15 years	2,874
15 to 20 years	2,412
20 years and above	3,025
Net Par Outstanding (excluding loss mitigation bonds)	$50,247		$72,928
[1]	Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.
[2]	Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of December 31, 2013, which are primarily in the BIG category.

Outstanding_Exposure_Component

Outstanding Exposure - Components of BIG Net Par Outstanding (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	$403,729	[1]	$459,107	[2]
TruPS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	4,326		4,970
Other structured finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	36,504		54,237
Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	353,482		386,179
BIG [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	18,247		22,538
BIG [Member] | TruPS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,333		1,722
BIG [Member] | Other structured finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	2,017		2,397
BIG [Member] | BIG 1 [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	11,865		14,751
BIG [Member] | BIG 1 [Member] | TruPS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	997		1,587
BIG [Member] | BIG 1 [Member] | Other structured finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,021		1,367
BIG [Member] | BIG 2 [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	2,689		3,949
BIG [Member] | BIG 2 [Member] | TruPS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	0		135
BIG [Member] | BIG 2 [Member] | Other structured finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	240		309
BIG [Member] | BIG 3 [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	3,693		3,838
BIG [Member] | BIG 3 [Member] | TruPS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	336		0
BIG [Member] | BIG 3 [Member] | Other structured finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	756		721
United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	363,294
United States [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	9,417		13,721
United States [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	322,123	[1]	352,181	[2]
United States [Member] | BIG [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	5,643		7,717
United States [Member] | BIG [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	7,850		9,094
United States [Member] | BIG [Member] | BIG 1 [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,868		2,583
United States [Member] | BIG [Member] | BIG 1 [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	6,577		8,205
United States [Member] | BIG [Member] | BIG 2 [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,291		2,466
United States [Member] | BIG [Member] | BIG 2 [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,156		440
United States [Member] | BIG [Member] | BIG 3 [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	2,484		2,668
United States [Member] | BIG [Member] | BIG 3 [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	117		449
Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	40,435
Non United States [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	31,359	[1]	33,998	[2]
Non United States [Member] | BIG [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,404		1,608
Non United States [Member] | BIG [Member] | BIG 1 [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,402		1,009
Non United States [Member] | BIG [Member] | BIG 2 [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	2		599
Non United States [Member] | BIG [Member] | BIG 3 [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	0		0
First Lien [Member] | United States [Member] | Prime [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	471		541
First Lien [Member] | United States [Member] | Alt-A [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	2,532		3,590
First Lien [Member] | United States [Member] | Option ARM [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	407		937
First Lien [Member] | United States [Member] | Subprime [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	4,051		6,130
First Lien [Member] | United States [Member] | BIG [Member] | Prime [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	353		403
First Lien [Member] | United States [Member] | BIG [Member] | Alt-A [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,841		2,728
First Lien [Member] | United States [Member] | BIG [Member] | Option ARM [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	183		598
First Lien [Member] | United States [Member] | BIG [Member] | Subprime [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,575		1,945
First Lien [Member] | United States [Member] | BIG [Member] | BIG 1 [Member] | Prime [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	68		52
First Lien [Member] | United States [Member] | BIG [Member] | BIG 1 [Member] | Alt-A [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	585		656
First Lien [Member] | United States [Member] | BIG [Member] | BIG 1 [Member] | Option ARM [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	47		71
First Lien [Member] | United States [Member] | BIG [Member] | BIG 1 [Member] | Subprime [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	156		297
First Lien [Member] | United States [Member] | BIG [Member] | BIG 2 [Member] | Prime [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	33		321
First Lien [Member] | United States [Member] | BIG [Member] | BIG 2 [Member] | Alt-A [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	531		1,137
First Lien [Member] | United States [Member] | BIG [Member] | BIG 2 [Member] | Option ARM [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	18		60
First Lien [Member] | United States [Member] | BIG [Member] | BIG 2 [Member] | Subprime [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	654		908
First Lien [Member] | United States [Member] | BIG [Member] | BIG 3 [Member] | Prime [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	252		30
First Lien [Member] | United States [Member] | BIG [Member] | BIG 3 [Member] | Alt-A [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	725		935
First Lien [Member] | United States [Member] | BIG [Member] | BIG 3 [Member] | Option ARM [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	118		467
First Lien [Member] | United States [Member] | BIG [Member] | BIG 3 [Member] | Subprime [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	765		740
Second Lien [Member] | United States [Member] | Closed-end [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	218		244
Second Lien [Member] | United States [Member] | HELOCs [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,738		2,279
Second Lien [Member] | United States [Member] | BIG [Member] | Closed-end [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	134		146
Second Lien [Member] | United States [Member] | BIG [Member] | HELOCs [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,557		1,897
Second Lien [Member] | United States [Member] | BIG [Member] | BIG 1 [Member] | Closed-end [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	0		8
Second Lien [Member] | United States [Member] | BIG [Member] | BIG 1 [Member] | HELOCs [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,012		1,499
Second Lien [Member] | United States [Member] | BIG [Member] | BIG 2 [Member] | Closed-end [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	19		20
Second Lien [Member] | United States [Member] | BIG [Member] | BIG 2 [Member] | HELOCs [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	36		20
Second Lien [Member] | United States [Member] | BIG [Member] | BIG 3 [Member] | Closed-end [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	115		118
Second Lien [Member] | United States [Member] | BIG [Member] | BIG 3 [Member] | HELOCs [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	$509		$378
[1]	Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.
[2]	Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of December 31, 2013, which are primarily in the BIG category.

Outstanding_Exposure_BIG_Net_P

Outstanding Exposure - BIG Net Par Outstanding (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified	risk
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, Credit Derivative	$34,996		$54,482
Net Par Outstanding (excluding loss mitigation bonds)	403,729	[1]	459,107	[2]
Number of Risks	13,161
BIG [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, Financial Guaranty Insurance	15,222	[3]	17,745	[3]
Net Par Outstanding, Credit Derivative	3,025		4,793
Net Par Outstanding (excluding loss mitigation bonds)	18,247		22,538
Number of Risks, Financial Guaranty Insurance	358	[3],[4]	384	[3],[4]
Number of Risks, Credit Derivative	56	[4]	73	[4]
Number of Risks	414	[4]	457	[4]
BIG [Member] | BIG 1 [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, Financial Guaranty Insurance	10,195	[3]	12,391	[3]
Net Par Outstanding, Credit Derivative	1,670		2,360
Net Par Outstanding (excluding loss mitigation bonds)	11,865		14,751
Number of Risks, Financial Guaranty Insurance	164	[3],[4]	185	[3],[4]
Number of Risks, Credit Derivative	18	[4]	25	[4]
Number of Risks	182	[4]	210	[4]
BIG [Member] | BIG 2 [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, Financial Guaranty Insurance	2,135	[3]	2,323	[3]
Net Par Outstanding, Credit Derivative	554		1,626
Net Par Outstanding (excluding loss mitigation bonds)	2,689		3,949
Number of Risks, Financial Guaranty Insurance	75	[3],[4]	80	[3],[4]
Number of Risks, Credit Derivative	14	[4]	21	[4]
Number of Risks	89	[4]	101	[4]
BIG [Member] | BIG 3 [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, Financial Guaranty Insurance	2,892	[3]	3,031	[3]
Net Par Outstanding, Credit Derivative	801		807
Net Par Outstanding (excluding loss mitigation bonds)	$3,693		$3,838
Number of Risks, Financial Guaranty Insurance	119	[3],[4]	119	[3],[4]
Number of Risks, Credit Derivative	24	[4]	27	[4]
Number of Risks	143	[4]	146	[4]
[1]	Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.
[2]	Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of December 31, 2013, which are primarily in the BIG category.
[3]	Includes net par outstanding for FG VIEs.
[4]	A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments.

Outstanding_Exposure_Geographi

Outstanding Exposure - Geographic Distribution of Net Par Outstanding (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified	risk
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	13,161
Net par amount outstanding	$403,729	[1]	$459,107	[2]
Percent of Total Net Par Outstanding	100.00%
United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	12,904
Net par amount outstanding	363,294
Percent of Total Net Par Outstanding	90.10%
Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	257
Net par amount outstanding	40,435
Percent of Total Net Par Outstanding	9.90%
United Kingdom [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	114
Net par amount outstanding	19,856
Percent of Total Net Par Outstanding	4.90%
Australia [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	26
Net par amount outstanding	4,121
Percent of Total Net Par Outstanding	1.00%
Canada [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	10
Net par amount outstanding	3,526
Percent of Total Net Par Outstanding	0.90%
France [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	20
Net par amount outstanding	2,820
Percent of Total Net Par Outstanding	0.70%
Italy [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	9
Net par amount outstanding	1,501
Percent of Total Net Par Outstanding	0.40%
Other Countries [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	78
Net par amount outstanding	8,611
Percent of Total Net Par Outstanding	2.00%
Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	353,482		386,179
Public Finance [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	12,065
Net par amount outstanding	322,123	[1]	352,181	[2]
Percent of Total Net Par Outstanding	79.90%
Public Finance [Member] | California [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	1,465
Net par amount outstanding	50,668
Percent of Total Net Par Outstanding	12.60%
Public Finance [Member] | Pennsylvania [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	1,009
Net par amount outstanding	26,173
Percent of Total Net Par Outstanding	6.50%
Public Finance [Member] | New York [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	995
Net par amount outstanding	26,044
Percent of Total Net Par Outstanding	6.50%
Public Finance [Member] | Texas [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	1,239
Net par amount outstanding	25,449
Percent of Total Net Par Outstanding	6.30%
Public Finance [Member] | Illinois [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	830
Net par amount outstanding	22,825
Percent of Total Net Par Outstanding	5.70%
Public Finance [Member] | Florida [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	384
Net par amount outstanding	19,470
Percent of Total Net Par Outstanding	4.80%
Public Finance [Member] | New Jersey [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	602
Net par amount outstanding	13,558
Percent of Total Net Par Outstanding	3.40%
Public Finance [Member] | Michigan [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	668
Net par amount outstanding	12,739
Percent of Total Net Par Outstanding	3.20%
Public Finance [Member] | Georgia [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	192
Net par amount outstanding	8,217
Percent of Total Net Par Outstanding	2.00%
Public Finance [Member] | Ohio [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	507
Net par amount outstanding	7,818
Percent of Total Net Par Outstanding	1.90%
Public Finance [Member] | Other States and U.S. Territories [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	4,174
Net par amount outstanding	109,162
Percent of Total Net Par Outstanding	27.00%
Public Finance [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	31,359	[1]	33,998	[2]
Structured Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	50,247		72,928
Structured Finance [Member] | United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Number of Risks	839
Net par amount outstanding	41,171	[1]	58,907	[2]
Percent of Total Net Par Outstanding	10.20%
Structured Finance [Member] | Non United States [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	$9,076	[1]	$14,021	[2]
[1]	Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.
[2]	Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of December 31, 2013, which are primarily in the BIG category.

Outstanding_Exposure_Net_Direc

Outstanding Exposure - Net Direct Economic Exposure to Selected European Countries (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	$2,353	[1]
BIG [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	900	[1]
Hungary [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	499	[1]
Hungary [Member] | BIG [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	424	[1]
Italy [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	1,378	[1]
Italy [Member] | BIG [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	0	[1]
Portugal [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	102	[1]
Portugal [Member] | BIG [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	102	[1]
Spain [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	374	[1]
Spain [Member] | BIG [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	374	[1]
Total Sovereign Exposure [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	1,680	[1]
Total Sovereign Exposure [Member] | Non-Infrastructure Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	1,208	[1],[2]
Total Sovereign Exposure [Member] | Infrastructure finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	472	[1]
Total Sovereign Exposure [Member] | Hungary [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	313	[1]
Total Sovereign Exposure [Member] | Hungary [Member] | Non-Infrastructure Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	0	[1],[2]
Total Sovereign Exposure [Member] | Hungary [Member] | Infrastructure finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	313	[1]
Total Sovereign Exposure [Member] | Italy [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	891	[1]
Total Sovereign Exposure [Member] | Italy [Member] | Non-Infrastructure Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	878	[1],[2]
Total Sovereign Exposure [Member] | Italy [Member] | Infrastructure finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	13	[1]
Total Sovereign Exposure [Member] | Portugal [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	102	[1]
Total Sovereign Exposure [Member] | Portugal [Member] | Non-Infrastructure Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	91	[1],[2]
Total Sovereign Exposure [Member] | Portugal [Member] | Infrastructure finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	11	[1]
Total Sovereign Exposure [Member] | Spain [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	374	[1]
Total Sovereign Exposure [Member] | Spain [Member] | Non-Infrastructure Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	239	[1],[2]
Total Sovereign Exposure [Member] | Spain [Member] | Infrastructure finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	135	[1]
Total Non-sovereign Exposure [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	673	[1]
Total Non-sovereign Exposure [Member] | Regulated utilities [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	220	[1]
Total Non-sovereign Exposure [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	453	[1]
Total Non-sovereign Exposure [Member] | Hungary [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	186	[1]
Total Non-sovereign Exposure [Member] | Hungary [Member] | Regulated utilities [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	0	[1]
Total Non-sovereign Exposure [Member] | Hungary [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	186	[1]
Total Non-sovereign Exposure [Member] | Italy [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	487	[1]
Total Non-sovereign Exposure [Member] | Italy [Member] | Regulated utilities [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	220	[1]
Total Non-sovereign Exposure [Member] | Italy [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	267	[1]
Total Non-sovereign Exposure [Member] | Portugal [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	0	[1]
Total Non-sovereign Exposure [Member] | Portugal [Member] | Regulated utilities [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	0	[1]
Total Non-sovereign Exposure [Member] | Portugal [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	0	[1]
Total Non-sovereign Exposure [Member] | Spain [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	0	[1]
Total Non-sovereign Exposure [Member] | Spain [Member] | Regulated utilities [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	0	[1]
Total Non-sovereign Exposure [Member] | Spain [Member] | RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, European Exposure	$0	[1]
[1]	(1)While the Company’s exposures are shown in U.S. dollars, the obligations the Company insures are in various currencies, primarily Euros. One of the residential mortgage-backed securities included in the table above includes residential mortgages in both Italy and Germany, and only the portion of the transaction equal to the portion of the original mortgage pool in Italian mortgages is shown in the table.
[2]	(2)The exposure shown in the “Non-infrastructure public finance” category is from transactions backed by receivable payments from sub-sovereigns in Italy, Spain and Portugal. Sub-sovereign debt is debt issued by a governmental entity or government backed entity, or supported by such an entity, that is other than direct sovereign debt of the ultimate governing body of the country.

Outstanding_Exposure_Puerto_Ri

Outstanding Exposure - Puerto Rico Gross Par and Gross Debt Service Outstanding (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	$426,704		$487,895
Gross Debt Service Outstanding	646,722		737,380
Puerto Rico [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	6,035		6,796
Gross Debt Service Outstanding	10,074		11,347
Subject to the Terms of the Recovery Act [Member] | Puerto Rico [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	3,058	[1]	3,279	[1]
Gross Debt Service Outstanding	5,326	[1]	5,748	[1]
Not Subject to the Terms of the Recovery Act [Member] | Puerto Rico [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	2,977		3,517
Gross Debt Service Outstanding	$4,748		$5,599
[1]	On February 6, 2015, the U.S. District Court for the District of Puerto Rico ruled that the Recovery Act is preempted by the Federal Bankruptcy Code and is therefore void. On February 19, 2015, the Commonwealth appealed the ruling to the U.S. Court of Appeals for the First Circuit.

Outstanding_Exposure_Puerto_Ri1

Outstanding Exposure - Puerto Rico Net Par Outstanding (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	$403,729	[1]	$459,107	[2]
Puerto Rico [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	4,939		5,441
Puerto Rico [Member] | Subject to the Terms of the Recovery Act [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	2,447		2,647
Puerto Rico [Member] | Subject to the Terms of the Recovery Act [Member] | PRHTA (Transportation revenue) [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	844		872
Puerto Rico [Member] | Subject to the Terms of the Recovery Act [Member] | PREPA [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	772		860
Puerto Rico [Member] | Subject to the Terms of the Recovery Act [Member] | Puerto Rico Aqueduct and Sewer Authority [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	384		384
Puerto Rico [Member] | Subject to the Terms of the Recovery Act [Member] | PRHTA (Highway revenue) [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	273		302
Puerto Rico [Member] | Subject to the Terms of the Recovery Act [Member] | Puerto Rico Convention Center District Authority [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	174		185
Puerto Rico [Member] | Subject to the Terms of the Recovery Act [Member] | Puerto Rico Public Finance Corporation [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	0		44
Puerto Rico [Member] | Not Subject to the Terms of the Recovery Act [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	2,492		2,794
Puerto Rico [Member] | Not Subject to the Terms of the Recovery Act [Member] | Commonwealth of Puerto Rico - General Obligation Bonds [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	1,672		1,885
Puerto Rico [Member] | Not Subject to the Terms of the Recovery Act [Member] | Puerto Rico Municipal Finance Agency [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	399		450
Puerto Rico [Member] | Not Subject to the Terms of the Recovery Act [Member] | Puerto Rico Sales Tax Financing Corporation [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	269		268
Puerto Rico [Member] | Not Subject to the Terms of the Recovery Act [Member] | Puerto Rico Public Buildings Authority [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	100		139
Puerto Rico [Member] | Not Subject to the Terms of the Recovery Act [Member] | GDB [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	33		33
Puerto Rico [Member] | Not Subject to the Terms of the Recovery Act [Member] | PRIFA [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	18		18
Puerto Rico [Member] | Not Subject to the Terms of the Recovery Act [Member] | University of Puerto Rico [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	$1		$1
[1]	Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.
[2]	Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of December 31, 2013, which are primarily in the BIG category.

Outstanding_Exposure_Amortizat

Outstanding Exposure - Amortization Schedule of Puerto Rico BIG Net Par Outstanding and BIG Net Debt Service Outstanding (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Estimated BIG Net Par Amortization [Abstract]
Net Par Outstanding (excluding loss mitigation bonds)	$403,729	[1]	$459,107	[2]
Estimated BIG Net Debt Service Amortization [Abstract]
Total	609,622		690,535
Puerto Rico [Member]
Estimated BIG Net Par Amortization [Abstract]
Net Par Outstanding (excluding loss mitigation bonds)	4,939		5,441
BIG [Member]
Estimated BIG Net Par Amortization [Abstract]
Net Par Outstanding (excluding loss mitigation bonds)	18,247		22,538
BIG [Member] | Puerto Rico [Member]
Estimated BIG Net Par Amortization [Abstract]
2015	331
2016	267
2017	207
2018	157
2019	187
2020	255
2021	109
2022	109
2023	142
2024	160
2025-2029	916
2030-2034	827
2035-2039	667
2040-2044	90
2045-2047	246
Net Par Outstanding (excluding loss mitigation bonds)	4,670
Estimated BIG Net Debt Service Amortization [Abstract]
2015	568
2016	486
2017	415
2018	353
2019	375
2020	434
2021	275
2022	269
2023	297
2024	310
2025-2029	1,517
2030-2034	1,237
2035-2039	830
2040-2044	160
2045-2047	271
Total	7,797
Subject to the Terms of the Recovery Act [Member] | Puerto Rico [Member]
Estimated BIG Net Par Amortization [Abstract]
Net Par Outstanding (excluding loss mitigation bonds)	2,447		2,647
Subject to the Terms of the Recovery Act [Member] | BIG [Member] | Puerto Rico [Member]
Estimated BIG Net Par Amortization [Abstract]
2015	126
2016	84
2017	41
2018	48
2019	61
2020	73
2021	51
2022	42
2023	102
2024	82
2025-2029	576
2030-2034	440
2035-2039	397
2040-2044	78
2045-2047	246
Net Par Outstanding (excluding loss mitigation bonds)	2,447
Estimated BIG Net Debt Service Amortization [Abstract]
2015	249
2016	199
2017	153
2018	158
2019	168
2020	176
2021	151
2022	140
2023	198
2024	174
2025-2029	951
2030-2034	696
2035-2039	526
2040-2044	147
2045-2047	271
Total	4,357
Not Subject to the Terms of the Recovery Act [Member] | Puerto Rico [Member]
Estimated BIG Net Par Amortization [Abstract]
Net Par Outstanding (excluding loss mitigation bonds)	2,492		2,794
Not Subject to the Terms of the Recovery Act [Member] | BIG [Member] | Puerto Rico [Member]
Estimated BIG Net Par Amortization [Abstract]
2015	205
2016	183
2017	166
2018	109
2019	126
2020	182
2021	58
2022	67
2023	40
2024	78
2025-2029	340
2030-2034	387
2035-2039	270
2040-2044	12
2045-2047	0
Net Par Outstanding (excluding loss mitigation bonds)	2,223
Estimated BIG Net Debt Service Amortization [Abstract]
2015	319
2016	287
2017	262
2018	195
2019	207
2020	258
2021	124
2022	129
2023	99
2024	136
2025-2029	566
2030-2034	541
2035-2039	304
2040-2044	13
2045-2047	0
Total	$3,440
[1]	Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.
[2]	Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of December 31, 2013, which are primarily in the BIG category.

Outstanding_Exposure_Narrative

Outstanding Exposure - Narrative (Details) (USD $)	12 Months Ended		0 Months Ended
	Dec. 31, 2014		Jul. 17, 2014	Dec. 31, 2013		Aug. 14, 2014
Schedule of Insured Financial Obligations [Line Items]
Probability of paying more claims than being reimbursed (as a percent)	50.00%
Net Debt Service Outstanding	$609,622,000,000			$690,535,000,000
Indirect European exposure	11,600,000,000
Net par amount outstanding	403,729,000,000	[1]		459,107,000,000	[2]
RMBS [Member]
Schedule of Insured Financial Obligations [Line Items]
Minimum principal amount assumed for internal rating	1,000,000
Pooled corporate obligations [Member]
Schedule of Insured Financial Obligations [Line Items]
Indirect European exposure	864,000,000
Structured Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Debt Service Outstanding	56,010,000,000			80,524,000,000
Net par amount outstanding	50,247,000,000			72,928,000,000
Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Debt Service Outstanding	553,612,000,000			610,011,000,000
Net par amount outstanding	353,482,000,000			386,179,000,000
BIG [Member]
Schedule of Insured Financial Obligations [Line Items]
Maximum period of liquidity claims (in years)	1 year
Net par amount outstanding	18,247,000,000			22,538,000,000
United Kingdom and Ireland [Member] | Mortgage Loans on Real Estate [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Debt Service Outstanding	127,000,000
United Kingdom and Ireland [Member] | Mortgage Loans on Real Estate [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Debt Service Outstanding				152,000,000
Select European Countries [Member]
Schedule of Insured Financial Obligations [Line Items]
Indirect European exposure	418,000,000
Greece [Member] | Pooled corporate obligations [Member]
Schedule of Insured Financial Obligations [Line Items]
Indirect European exposure	12,000,000
Puerto Rico [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	4,939,000,000			5,441,000,000
Deposit in reserve account utilized to pay debt service due on bonds			42,000,000
Percentage of outstanding bonds of PREPA						60.00%
Puerto Rico [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	4,900,000,000
Puerto Rico [Member] | BIG [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Debt Service Outstanding	7,797,000,000
Net par amount outstanding	4,670,000,000
Puerto Rico [Member] | BIG [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Net par amount outstanding	4,700,000,000
Commitment to Provide Guarantees [Member] | Structured Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Outstanding commitments to provide guaranties	276,000,000
Commitment to Provide Guarantees [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Outstanding commitments to provide guaranties	248,000,000
Outstanding commitments to provide guaranties, amount expiring prior to December 31, 2014	$124,000,000
Minimum [Member]
Schedule of Insured Financial Obligations [Line Items]
Constant discount rate (as a percent)	4.50%
Minimum [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Expiration date for insured financial obligation commitments	15-Jan-15
Minimum [Member] | BIG [Member]
Schedule of Insured Financial Obligations [Line Items]
Constant discount rate (as a percent)	4.50%
Maximum [Member]
Schedule of Insured Financial Obligations [Line Items]
Constant discount rate (as a percent)	5.00%
Maximum [Member] | Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Expiration date for insured financial obligation commitments	17-Feb-17
Maximum [Member] | BIG [Member]
Schedule of Insured Financial Obligations [Line Items]
Constant discount rate (as a percent)	5.00%
[1]	Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.
[2]	Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of December 31, 2013, which are primarily in the BIG category.

Financial_Guaranty_Insurance_P2

Financial Guaranty Insurance Premiums - Net Earned Premiums (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Financial Guarantee Insurance Premiums [Line Items]
Net earned premiums	$158	$144	$136	$132	$182	$159	$163	$248	$570		$752		$853
Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Financial Guarantee Insurance Premiums [Line Items]
Scheduled net earned premiums									415		470		581
Acceleration of net earned premiums									136		263		249
Accretion of discount on net premiums receivable									16		17		22
Financial guaranty insurance net earned premiums									567		750		852
Other									3		2		1
Net earned premiums									570	[1]	752	[1]	853	[1]
Variable Interest Entity, Primary Beneficiary [Member]
Financial Guarantee Insurance Premiums [Line Items]
Net earned premiums									$32		$60		$153
[1]	Excludes $32 million, $60 million and $153 million for the year ended December 31, 2014, 2013 and 2012, respectively, related to consolidated FG VIEs.

Financial_Guaranty_Insurance_P3

Financial Guaranty Insurance Premiums - Components of Unearned Premium Reserve (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Financial Guarantee Insurance Premiums [Line Items]
Unearned premium reserve, gross	$4,261		$4,595
Unearned premium reserve, ceded	381		452
Total net unearned premium reserve related to FG VIE	125		187
Contra-paid related to FG and VIEs	42		55
Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Financial Guarantee Insurance Premiums [Line Items]
Deferred premium revenue, gross	4,167		4,652
Deferred premium revenue, ceded	387		470
Deferred premium revenue, net	3,780	[1],[2]	4,182	[1]
Contra-paid, gross	94	[3]	-57	[3]
Contra-paid, ceded	-6	[3]	-18	[3]
Contra-paid, net	100	[1],[3]	-39	[1],[3]
Unearned premium reserve, gross	4,261		4,595
Unearned premium reserve, ceded	381		452
Unearned premium reserve, net	3,880	[1]	4,143	[1]
Financial Guarantee Insurance Product Line [Member]
Financial Guarantee Insurance Premiums [Line Items]
Contra-paid, net	100
Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Financial Guarantee Insurance Premiums [Line Items]
Deferred premium revenue, gross	4,167		4,647
Deferred premium revenue, ceded	387		470
Deferred premium revenue, net	3,780	[1]	4,177	[1]
Other Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Financial Guarantee Insurance Premiums [Line Items]
Deferred premium revenue, gross	0		5
Deferred premium revenue, ceded	0		0
Deferred premium revenue, net	$0	[1]	$5	[1]
[1]	Excludes $125 million and $187 million deferred premium revenue and $42 million and $55 million of contra-paid related to FG VIEs as of December 31, 2014 and December 31, 2013, respectively.
[2]	Excludes scheduled net earned premiums on consolidated FG VIEs of $125 million
[3]	See Note 7, "Financial Guaranty Insurance Losses– Insurance Contracts' Loss Information" for an explanation of "contra-paid".

Financial_Guaranty_Insurance_P4

Financial Guaranty Insurance Premiums - Gross Premium Receivable Net of Commissions on Assumed Business Roll Forward (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Gross Premium Receivable Net of Ceding Commissions [Roll Forward]
Beginning of period, December 31	$876	[1]	$1,005	[1]	$1,003
Gross premium written, net of commissions on assumed business	171		145		211
Gross premiums received, net of commissions on assumed business	-230		-259		-294
Changes in the expected term	-66		-28		44
Accretion of discount, net of commissions on assumed business	10		20		36
Foreign exchange translation	-31		-1		13
Consolidation/deconsolidation of FG VIEs	-1		0		-5
Other adjustments	0		-6		-3
End of period, December 31	729	[1]	876	[1]	1,005	[1]
Variable Interest Entity, Primary Beneficiary [Member]
Gross Premium Receivable Net of Ceding Commissions [Roll Forward]
End of period, December 31	$19		$21		$29
Foreign Currency Concentration Risk [Member] | Premiums Receivable [Member]
Gross Premium Receivable Net of Ceding Commissions [Roll Forward]
Percentage of installment premiums denominated in currencies other than the U.S. dollar	51.00%		48.00%
[1]	Excludes $19 million, $21 million and $29 million as of December 31, 2014 , 2013 and 2012, respectively, related to consolidated FG VIEs.

Financial_Guaranty_Insurance_P5

Financial Guaranty Insurance Premiums - Expected Collections of Gross Premiums Receivable Net of Commissions on Assumed Business (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Financial Guarantee Insurance Premiums [Line Items]
2015 (January 1 – March 31)	$31
2015 (April 1 – June 30)	26
2015 (July 1 – September 30)	20
2015 (October 1 – December 31)	20
2016	74
2017	69
2018	62
2019	58
2020-2024	242
2025-2029	154
2030-2034	106
After 2034	102
Total	964	[1]
Variable Interest Entity, Primary Beneficiary [Member]
Financial Guarantee Insurance Premiums [Line Items]
Cash collections on FG VIEs	$25
[1]	Excludes expected cash collections on FG VIEs of $25 million.

Financial_Guaranty_Insurance_P6

Financial Guaranty Insurance Premiums - Scheduled Net Earned Premiums Insurance Contracts (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Variable Interest Entity, Primary Beneficiary [Member]
Financial Guarantee Insurance Premiums [Line Items]
Deferred premium revenue, net	$125
Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Financial Guarantee Insurance Premiums [Line Items]
2015 (January 1 – March 31)	93
2015 (April 1 – June 30)	91
2015 (July 1 – September 30)	89
2015 (October 1 – December 31)	86
Subtotal 2015	359
2016	332
2017	295
2018	269
2019	246
2020-2024	968
2025-2029	615
2030-2034	370
After 2034	326
Deferred premium revenue, net	3,780	[1],[2]	4,182	[2]
Discount	208
Total future value	$3,988
[1]	Excludes scheduled net earned premiums on consolidated FG VIEs of $125 million
[2]	Excludes $125 million and $187 million deferred premium revenue and $42 million and $55 million of contra-paid related to FG VIEs as of December 31, 2014 and December 31, 2013, respectively.

Financial_Guaranty_Insurance_P7

Financial Guaranty Insurance Premiums - Selected Information for Policies Paid in Installments (Details) (Policies Paid in Installments [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Policies Paid in Installments [Member]
Financial Guarantee Insurance Premiums [Line Items]
Premiums receivable, net of commission payable	$729	$876
Gross deferred premium revenue	$1,370	$1,576
Weighted-average risk-free rate used to discount premiums (as a percent)	3.50%	3.40%
Weighted-average period of premiums receivable (in years)	9 years 4 months 24 days	9 years 4 months 24 days

Financial_Guaranty_Insurance_A2

Financial Guaranty Insurance Acquisition Costs (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning of period	$124	$116	$132
Commissions on assumed and ceded business	7	9	-13
Premium taxes	3	4	4
Compensation and other acquisition costs	10	8	10
Total costs deferred	20	21	1
Amortization of deferred acquisition costs	-23	-13	-17
End of period	$121	$124	$116

Expected_Loss_to_be_Paid_Net_E

Expected Loss to be Paid - Net Expected Loss to be Paid Before Recoveries for Breaches of R&W (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	$1,694	[1]	$2,047
Economic Loss Development Before Recoveries for R&W	238		352
(Paid) Recovered Losses Before Recoveries for R&W	-446	[2]	-705	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	1,486	[1]	1,694	[1]
Period after the end of the reporting period within which the ceded paid losses are typically settled (in days)	45 days
Loss and loss adjustment expense reserve	799		592
Loss and LAE Reserve paid	37		54
Expected LAE to be paid	16		34
RMBS [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	1,205	[1]	1,652
Economic Loss Development Before Recoveries for R&W	0		140
(Paid) Recovered Losses Before Recoveries for R&W	-304	[2]	-587	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	901	[1]	1,205	[1]
RMBS [Member] | First Lien [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	1,189	[1]	1,514
Economic Loss Development Before Recoveries for R&W	-32		140
(Paid) Recovered Losses Before Recoveries for R&W	-330	[2]	-465	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	827	[1]	1,189	[1]
RMBS [Member] | First Lien [Member] | Prime [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	25	[1]	10
Economic Loss Development Before Recoveries for R&W	-17		16
(Paid) Recovered Losses Before Recoveries for R&W	-2	[2]	-1	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	6	[1]	25	[1]
RMBS [Member] | First Lien [Member] | Alt-A [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	578	[1]	693
Economic Loss Development Before Recoveries for R&W	-13		-40
(Paid) Recovered Losses Before Recoveries for R&W	-155	[2]	-75	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	410	[1]	578	[1]
RMBS [Member] | First Lien [Member] | Option ARM [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	164	[1]	460
Economic Loss Development Before Recoveries for R&W	-45		63
(Paid) Recovered Losses Before Recoveries for R&W	-120	[2]	-359	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	-1	[1]	164	[1]
RMBS [Member] | First Lien [Member] | Subprime [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	422	[1]	351
Economic Loss Development Before Recoveries for R&W	43		101
(Paid) Recovered Losses Before Recoveries for R&W	-53	[2]	-30	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	412	[1]	422	[1]
RMBS [Member] | Second Lien [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	16	[1]	138
Economic Loss Development Before Recoveries for R&W	32		0
(Paid) Recovered Losses Before Recoveries for R&W	26	[2]	-122	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	74	[1]	16	[1]
RMBS [Member] | Second Lien [Member] | Closed-end [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	87	[1]	99
Economic Loss Development Before Recoveries for R&W	-3		-3
(Paid) Recovered Losses Before Recoveries for R&W	9	[2]	-9	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	93	[1]	87	[1]
RMBS [Member] | Second Lien [Member] | HELOCs [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	-71	[1]	39
Economic Loss Development Before Recoveries for R&W	35		3
(Paid) Recovered Losses Before Recoveries for R&W	17	[2]	-113	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	-19	[1]	-71	[1]
TruPS [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	51	[1]	27
Economic Loss Development Before Recoveries for R&W	-28		7
(Paid) Recovered Losses Before Recoveries for R&W	0	[2]	17	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	23	[1]	51	[1]
Structured Finance [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	120	[1]	312
Economic Loss Development Before Recoveries for R&W	96		-41
(Paid) Recovered Losses Before Recoveries for R&W	2	[2]	-151	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	218	[1]	120	[1]
Public Finance [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	264	[1]	7
Economic Loss Development Before Recoveries for R&W	183		239
(Paid) Recovered Losses Before Recoveries for R&W	-144	[2]	18	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	303	[1]	264	[1]
Public Finance [Member] | Non United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	57	[1]	52
Economic Loss Development Before Recoveries for R&W	-12		17
(Paid) Recovered Losses Before Recoveries for R&W	0	[2]	-12	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	45	[1]	57	[1]
Other Insurance Product Line [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid Before Recoveries for R&W	-3	[1]	-3
Economic Loss Development Before Recoveries for R&W	-1		-10
(Paid) Recovered Losses Before Recoveries for R&W	0	[2]	10	[2]
End of Period, Net Expected Loss to be Paid Before Recoveries for R&W	($4)	[1]	($3)	[1]
[1]	Includes expected LAE to be paid of $16 million as of December 31, 2014 and $34 million as of December 31, 2013.
[2]	Net of ceded paid losses, whether or not such amounts have been settled with reinsurers. Ceded paid losses are typically settled 45 days after the end of the reporting period. Such amounts are recorded in reinsurance recoverable on paid losses included in other assets.

Expected_Loss_to_be_Paid_Net_E1

Expected Loss to be Paid - Net Expected Recoveries from Breaches of R&W Rollforward (Details) (RMBS [Member], United States [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	$712		$1,370
R&W development and accretion of discount during period	268		296
R&W recovered during period	-663		-954
Future net R&W benefit at the end of the period	317	[1]	712
First Lien [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	569		1,082
R&W development and accretion of discount during period	194		211
R&W recovered during period	-531		-724
Future net R&W benefit at the end of the period	232	[1]	569
First Lien [Member] | Prime [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	4		4
R&W development and accretion of discount during period	-1		0
R&W recovered during period	-1		0
Future net R&W benefit at the end of the period	2	[1]	4
First Lien [Member] | Alt-A [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	274		378
R&W development and accretion of discount during period	131		41
R&W recovered during period	-299		-145
Future net R&W benefit at the end of the period	106	[1]	274
First Lien [Member] | Option ARM [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	173		591
R&W development and accretion of discount during period	14		161
R&W recovered during period	-172		-579
Future net R&W benefit at the end of the period	15	[1]	173
First Lien [Member] | Subprime [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	118		109
R&W development and accretion of discount during period	50		9
R&W recovered during period	-59		0
Future net R&W benefit at the end of the period	109	[1]	118
Second Lien [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	143		288
R&W development and accretion of discount during period	74		85
R&W recovered during period	-132		-230
Future net R&W benefit at the end of the period	85	[1]	143
Second Lien [Member] | Closed-end [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	98		138
R&W development and accretion of discount during period	-6		-9
R&W recovered during period	-7		-31
Future net R&W benefit at the end of the period	85	[1]	98
Second Lien [Member] | HELOCs [Member]
Estimated Benefit From Recoveries From Breaches of R and W Net of Reinsurance [Roll Forward]
Future net R&W benefit at the beginning of the period	45		150
R&W development and accretion of discount during period	80		94
R&W recovered during period	-125		-199
Future net R&W benefit at the end of the period	$0	[1]	$45
[1]	See the section "Breaches of Representations and Warranties" below for eligible assets held in trust.

Expected_Loss_to_be_Paid_Net_E2

Expected Loss to be Paid - Net Expected Loss to be Paid After Net Expected Recoveries for Breaches of R&W Rollforward (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	$982		$677
Economic loss development after recoveries for R&W	-30		56
(Paid) Recovered Losses After Recoveries for R&W	217	[1]	249	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	1,169		982
Period after the end of the reporting period within which the ceded paid losses are typically settled (in days)	45 days
RMBS [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	493		282
Economic loss development after recoveries for R&W	-268		-156
(Paid) Recovered Losses After Recoveries for R&W	359	[1]	367	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	584		493
RMBS [Member] | First Lien [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	620		432
Economic loss development after recoveries for R&W	-226		-71
(Paid) Recovered Losses After Recoveries for R&W	201	[1]	259	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	595		620
RMBS [Member] | First Lien [Member] | Prime [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	21		6
Economic loss development after recoveries for R&W	-16		16
(Paid) Recovered Losses After Recoveries for R&W	-1	[1]	-1	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	4		21
RMBS [Member] | First Lien [Member] | Alt-A [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	304		315
Economic loss development after recoveries for R&W	-144		-81
(Paid) Recovered Losses After Recoveries for R&W	144	[1]	70	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	304		304
RMBS [Member] | First Lien [Member] | Option ARM [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	-9		-131
Economic loss development after recoveries for R&W	-59		-98
(Paid) Recovered Losses After Recoveries for R&W	52	[1]	220	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	-16		-9
RMBS [Member] | First Lien [Member] | Subprime [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	304		242
Economic loss development after recoveries for R&W	-7		92
(Paid) Recovered Losses After Recoveries for R&W	6	[1]	-30	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	303		304
RMBS [Member] | Second Lien [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	-127		-150
Economic loss development after recoveries for R&W	-42		-85
(Paid) Recovered Losses After Recoveries for R&W	158	[1]	108	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	-11		-127
RMBS [Member] | Second Lien [Member] | Closed-end [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	-11		-39
Economic loss development after recoveries for R&W	3		6
(Paid) Recovered Losses After Recoveries for R&W	16	[1]	22	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	8		-11
RMBS [Member] | Second Lien [Member] | HELOCs [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	-116		-111
Economic loss development after recoveries for R&W	-45		-91
(Paid) Recovered Losses After Recoveries for R&W	142	[1]	86	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	-19		-116
TruPS [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	51		27
Economic loss development after recoveries for R&W	-28		7
(Paid) Recovered Losses After Recoveries for R&W	0	[1]	17	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	23		51
Other structured finance [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	120		312
Economic loss development after recoveries for R&W	96		-41
(Paid) Recovered Losses After Recoveries for R&W	2	[1]	-151	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	218		120
Public Finance [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	264		7
Economic loss development after recoveries for R&W	183		239
(Paid) Recovered Losses After Recoveries for R&W	-144	[1]	18	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	303		264
Public Finance [Member] | Non United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	57		52
Economic loss development after recoveries for R&W	-12		17
(Paid) Recovered Losses After Recoveries for R&W	0	[1]	-12	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	45		57
Other Insurance Product Line [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss to be Paid After Recoveries for R&W	-3		-3
Economic loss development after recoveries for R&W	-1		-10
(Paid) Recovered Losses After Recoveries for R&W	0	[1]	10	[1]
End of Period, Net Expected Loss to be Paid After Recoveries for R&W	($4)		($3)
[1]	Net of ceded paid losses, whether or not such amounts have been settled with reinsurers. Ceded paid losses and recoveries are typically settled 45 days after the end of the reporting period. Such amounts are recorded in reinsurance recoverable on paid losses included in other assets.

Expected_Loss_to_be_Paid_Net_E3

Expected Loss to be Paid - Net Expected Loss to be Paid and Net Economic Loss Development by Accounting Model (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	$1,169		$982		$677
Economic loss development after recoveries for R&W	-30		56
RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	584		493		282
Economic loss development after recoveries for R&W	-268		-156
RMBS [Member] | First Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	595		620		432
Economic loss development after recoveries for R&W	-226		-71
RMBS [Member] | First Lien [Member] | Prime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	4		21		6
Economic loss development after recoveries for R&W	-16		16
RMBS [Member] | First Lien [Member] | Alt-A [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	304		304		315
Economic loss development after recoveries for R&W	-144		-81
RMBS [Member] | First Lien [Member] | Option ARM [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	-16		-9		-131
Economic loss development after recoveries for R&W	-59		-98
RMBS [Member] | First Lien [Member] | Subprime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	303		304		242
Economic loss development after recoveries for R&W	-7		92
RMBS [Member] | Second Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	-11		-127		-150
Economic loss development after recoveries for R&W	-42		-85
RMBS [Member] | Second Lien [Member] | Closed-end [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	8		-11		-39
Economic loss development after recoveries for R&W	3		6
RMBS [Member] | Second Lien [Member] | HELOCs [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	-19		-116		-111
Economic loss development after recoveries for R&W	-45		-91
TruPS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	23		51		27
Economic loss development after recoveries for R&W	-28		7
Structured Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	218		120		312
Economic loss development after recoveries for R&W	96		-41
Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	303		264		7
Economic loss development after recoveries for R&W	183		239
Public Finance [Member] | Non United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	45		57		52
Economic loss development after recoveries for R&W	-12		17
Subtotal [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	1,173		985
Economic loss development after recoveries for R&W	-29		66
Other Insurance Product Line [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	-4		-3		-3
Economic loss development after recoveries for R&W	-1		-10
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	385		258
Economic loss development after recoveries for R&W	-280		-130
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | First Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	438		333
Economic loss development after recoveries for R&W	-150		-69
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | First Lien [Member] | Prime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	2		3
Economic loss development after recoveries for R&W	0		-1
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | First Lien [Member] | Alt-A [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	288		199
Economic loss development after recoveries for R&W	-87		-54
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | First Lien [Member] | Option ARM [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	-15		-18
Economic loss development after recoveries for R&W	-48		-62
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | First Lien [Member] | Subprime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	163		149
Economic loss development after recoveries for R&W	-15		48
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | Second Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	-53		-75
Economic loss development after recoveries for R&W	-130		-61
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | Second Lien [Member] | Closed-end [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	-27		-34
Economic loss development after recoveries for R&W	-2		30
Financial Guarantee Accounted for as Insurance Contracts [Member] | RMBS [Member] | Second Lien [Member] | HELOCs [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	-26		-41
Economic loss development after recoveries for R&W	-128		-91
Financial Guarantee Accounted for as Insurance Contracts [Member] | TruPS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	1		3
Economic loss development after recoveries for R&W	-2		0
Financial Guarantee Accounted for as Insurance Contracts [Member] | Structured Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	255		161
Economic loss development after recoveries for R&W	97		-36
Financial Guarantee Accounted for as Insurance Contracts [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	303		264
Economic loss development after recoveries for R&W	183		239
Financial Guarantee Accounted for as Insurance Contracts [Member] | Public Finance [Member] | Non United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	45		55
Economic loss development after recoveries for R&W	-10		16
Financial Guarantee Accounted for as Insurance Contracts [Member] | Subtotal [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	989		741
Economic loss development after recoveries for R&W	-12		89
Financial Guaranty Variable Interest Entities [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	126	[1]	60	[1]
Economic loss development after recoveries for R&W	85	[1]	-34	[1]
Financial Guaranty Variable Interest Entities [Member] | RMBS [Member] | First Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	88	[1]	110	[1]
Economic loss development after recoveries for R&W	-6	[1]	1	[1]
Financial Guaranty Variable Interest Entities [Member] | RMBS [Member] | First Lien [Member] | Prime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	0	[1]	0	[1]
Economic loss development after recoveries for R&W	0	[1]	0	[1]
Financial Guaranty Variable Interest Entities [Member] | RMBS [Member] | First Lien [Member] | Alt-A [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	17	[1]	31	[1]
Economic loss development after recoveries for R&W	-13	[1]	5	[1]
Financial Guaranty Variable Interest Entities [Member] | RMBS [Member] | First Lien [Member] | Option ARM [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	0	[1]	-2	[1]
Economic loss development after recoveries for R&W	1	[1]	-36	[1]
Financial Guaranty Variable Interest Entities [Member] | RMBS [Member] | First Lien [Member] | Subprime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	71	[1]	81	[1]
Economic loss development after recoveries for R&W	6	[1]	32	[1]
Financial Guaranty Variable Interest Entities [Member] | RMBS [Member] | Second Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	38	[1]	-50	[1]
Economic loss development after recoveries for R&W	91	[1]	-35	[1]
Financial Guaranty Variable Interest Entities [Member] | RMBS [Member] | Second Lien [Member] | Closed-end [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	31	[1]	25	[1]
Economic loss development after recoveries for R&W	8	[1]	-34	[1]
Financial Guaranty Variable Interest Entities [Member] | RMBS [Member] | Second Lien [Member] | HELOCs [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	7	[1]	-75	[1]
Economic loss development after recoveries for R&W	83	[1]	-1	[1]
Financial Guaranty Variable Interest Entities [Member] | TruPS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	0	[1]	0	[1]
Economic loss development after recoveries for R&W	0	[1]	0	[1]
Financial Guaranty Variable Interest Entities [Member] | Structured Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	0	[1]	0	[1]
Economic loss development after recoveries for R&W	0	[1]	0	[1]
Financial Guaranty Variable Interest Entities [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	0	[1]	0	[1]
Economic loss development after recoveries for R&W	0	[1]	0	[1]
Financial Guaranty Variable Interest Entities [Member] | Public Finance [Member] | Non United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	0	[1]	0	[1]
Economic loss development after recoveries for R&W	0	[1]	0	[1]
Financial Guaranty Variable Interest Entities [Member] | Subtotal [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	126	[1]	60	[1]
Economic loss development after recoveries for R&W	85	[1]	-34	[1]
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	73	[2]	175	[2]
Economic loss development after recoveries for R&W	-73	[2]	8	[2]
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | First Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	69	[2]	177	[2]
Economic loss development after recoveries for R&W	-70	[2]	-3	[2]
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | First Lien [Member] | Prime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	2	[2]	18	[2]
Economic loss development after recoveries for R&W	-16	[2]	17	[2]
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | First Lien [Member] | Alt-A [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	-1	[2]	74	[2]
Economic loss development after recoveries for R&W	-44	[2]	-32	[2]
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | First Lien [Member] | Option ARM [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	-1	[2]	11	[2]
Economic loss development after recoveries for R&W	-12	[2]	0	[2]
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | First Lien [Member] | Subprime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	69	[2]	74	[2]
Economic loss development after recoveries for R&W	2	[2]	12	[2]
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | Second Lien [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	4	[2]	-2	[2]
Economic loss development after recoveries for R&W	-3	[2]	11	[2]
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | Second Lien [Member] | Closed-end [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	4	[2]	-2	[2]
Economic loss development after recoveries for R&W	-3	[2]	10	[2]
Financial Guarantee Accounted for as Credit Derivatives [Member] | RMBS [Member] | Second Lien [Member] | HELOCs [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	0	[2]	0	[2]
Economic loss development after recoveries for R&W	0	[2]	1	[2]
Financial Guarantee Accounted for as Credit Derivatives [Member] | TruPS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	22	[2]	48	[2]
Economic loss development after recoveries for R&W	-26	[2]	7	[2]
Financial Guarantee Accounted for as Credit Derivatives [Member] | Structured Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	-37	[2]	-41	[2]
Economic loss development after recoveries for R&W	-1	[2]	-5	[2]
Financial Guarantee Accounted for as Credit Derivatives [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	0	[2]	0	[2]
Economic loss development after recoveries for R&W	0	[2]	0	[2]
Financial Guarantee Accounted for as Credit Derivatives [Member] | Public Finance [Member] | Non United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	0	[2]	2	[2]
Economic loss development after recoveries for R&W	-2	[2]	1	[2]
Financial Guarantee Accounted for as Credit Derivatives [Member] | Subtotal [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net expected loss to be paid after recoveries for R&W	58	[2]	184	[2]
Economic loss development after recoveries for R&W	($102)	[2]	$11	[2]
[1]	Refer to Note 10, Consolidated Variable Interest Entities.
[2]	Refer to Note 9, Financial Guaranty Contracts Accounted for as Credit Derivatives.

Expected_Loss_to_be_Paid_Liqui

Expected Loss to be Paid - Liquidation Rates and Key Assumptions in Base Case Expected Loss First Lien RMBS (Details)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Financing Receivable, Modified in Previous 12 Months [Member] | Alt-A and Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	25.00%		35.00%
Financing Receivable, Modified in Previous 12 Months [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	25.00%		35.00%
Financing Receivable, Modified in Previous 12 Months [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	25.00%		35.00%
Financing Receivable, Delinquent in the Previous 12 Months [Member] | Alt-A and Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	25.00%
Financing Receivable, Delinquent in the Previous 12 Months [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	25.00%
Financing Receivable, Delinquent in the Previous 12 Months [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	25.00%
Financing Receivables, 30 to 59 Days Past Due [Member] | Alt-A and Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	35.00%		50.00%		35.00%
Financing Receivables, 30 to 59 Days Past Due [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	40.00%		50.00%		50.00%
Financing Receivables, 30 to 59 Days Past Due [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	35.00%		45.00%		30.00%
Financing Receivables, 60 to 89 Days Past Due [Member] | Alt-A and Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	50.00%		60.00%		55.00%
Financing Receivables, 60 to 89 Days Past Due [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	55.00%		65.00%		65.00%
Financing Receivables, 60 to 89 Days Past Due [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	40.00%		50.00%		45.00%
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Alt-A and Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	60.00%		75.00%		65.00%
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	65.00%		70.00%		75.00%
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	55.00%		60.00%		60.00%
Financing Receivables, Bankruptcy [Member] | Alt-A and Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	45.00%		60.00%		55.00%
Financing Receivables, Bankruptcy [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	50.00%		60.00%		70.00%
Financing Receivables, Bankruptcy [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	40.00%		55.00%		50.00%
Financing Receivable, Foreclosure [Member] | Alt-A and Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	75.00%		85.00%		85.00%
Financing Receivable, Foreclosure [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	80.00%		80.00%		85.00%
Financing Receivable, Foreclosure [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	70.00%		70.00%		80.00%
Financing Receivable, Real Estate Owned [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liquidation Rate	100.00%		100.00%		100.00%
United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Period until intermediate CDR			48 months		36 months
United States [Member] | Subprime [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Period until intermediate CDR	48 months
Final CPR	15.00%	[1],[2]	15.00%	[1],[2]	15.00%	[1],[2]
United States [Member] | Subprime [Member] | 2005 and prior [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Initial loss severity	75.00%		90.00%		90.00%
United States [Member] | Subprime [Member] | 2006 [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Initial loss severity	90.00%		90.00%		90.00%
United States [Member] | Subprime [Member] | 2007 [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Initial loss severity	90.00%		90.00%		90.00%
United States [Member] | Subprime [Member] | Minimum [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	4.90%	[1]	5.60%	[1]	7.30%	[1]
Intermediate CDR	1.00%	[1]	1.10%	[1]	1.50%	[1]
Final CDR	0.20%	[1]	0.30%	[1]	0.40%	[1]
Initial CPR	0.00%	[1]	0.00%	[1]	0.00%	[1]
United States [Member] | Subprime [Member] | Maximum [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	15.00%	[1]	16.20%	[1]	26.20%	[1]
Intermediate CDR	3.00%	[1]	3.20%	[1]	5.20%	[1]
Final CDR	0.70%	[1]	0.80%	[1]	1.30%	[1]
Initial CPR	10.50%	[1]	15.70%	[1]	17.60%	[1]
United States [Member] | Subprime [Member] | Weighted Average [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	10.60%		11.80%		17.30%
Intermediate CDR	2.10%		2.40%		3.50%
Final CDR	0.40%		0.40%		0.60%
Initial CPR	6.10%		4.10%		3.60%
United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Period until intermediate CDR			48 months		36 months
United States [Member] | Option ARM [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Period until intermediate CDR	48 months
Final CPR	15.00%	[1]	15.00%	[1]	15.00%	[1]
United States [Member] | Option ARM [Member] | 2005 and prior [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Initial loss severity	60.00%		65.00%		65.00%
United States [Member] | Option ARM [Member] | 2006 [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Initial loss severity	70.00%		65.00%		65.00%
United States [Member] | Option ARM [Member] | 2007 [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Initial loss severity	65.00%		65.00%		65.00%
United States [Member] | Option ARM [Member] | Minimum [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	4.30%	[1]	4.90%	[1]	7.00%	[1]
Intermediate CDR	0.90%	[1]	1.00%	[1]	1.40%	[1]
Final CDR	0.20%	[1]	0.20%	[1]	0.40%	[1]
Initial CPR	1.10%	[1]	0.40%	[1]	0.00%	[1]
United States [Member] | Option ARM [Member] | Maximum [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	14.20%	[1]	16.80%	[1]	26.10%	[1]
Intermediate CDR	2.80%	[1]	3.40%	[1]	5.20%	[1]
Final CDR	0.70%	[1]	0.80%	[1]	1.30%	[1]
Initial CPR	11.80%	[1]	13.10%	[1]	10.70%	[1]
United States [Member] | Option ARM [Member] | Weighted Average [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	10.60%		11.90%		18.40%
Intermediate CDR	2.10%		2.40%		3.70%
Final CDR	0.50%		0.50%		0.80%
Initial CPR	4.90%		4.70%		4.00%
United States [Member] | Alt-A [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Period until intermediate CDR	48 months		48 months		36 months
Final CPR	15.00%	[1]	15.00%	[1]	15.00%	[1]
United States [Member] | Alt-A [Member] | 2005 and prior [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Initial loss severity	60.00%		65.00%		65.00%
United States [Member] | Alt-A [Member] | 2006 [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Initial loss severity	70.00%		65.00%		65.00%
United States [Member] | Alt-A [Member] | 2007 [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Initial loss severity	65.00%		65.00%		65.00%
United States [Member] | Alt-A [Member] | Minimum [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	2.00%	[1]	2.80%	[1]	3.80%	[1]
Intermediate CDR	0.40%	[1]	0.60%	[1]	0.80%	[1]
Final CDR	0.10%	[1]	0.10%	[1]	0.20%	[1]
Initial CPR	1.70%	[1]	0.00%	[1]	0.00%	[1]
United States [Member] | Alt-A [Member] | Maximum [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	13.40%	[1]	18.40%	[1]	23.20%	[1]
Intermediate CDR	2.70%	[1]	3.70%	[1]	4.60%	[1]
Final CDR	0.70%	[1]	0.90%	[1]	1.20%	[1]
Initial CPR	21.00%	[1]	34.20%	[1]	39.40%	[1]
United States [Member] | Alt-A [Member] | Weighted Average [Member] | RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	7.30%		9.70%		13.30%
Intermediate CDR	1.50%		1.90%		2.70%
Final CDR	0.30%		0.50%		0.60%
Initial CPR	7.70%		9.70%		7.40%
[1]	Represents variables for most heavily weighted scenario (the “base case”).
[2]	For transactions where the initial CPR is higher than the final CPR, the initial CPR is held constant and the final CPR is not used.

Expected_Loss_to_be_Paid_Key_A

Expected Loss to be Paid - Key Assumptions in Base Case Expected Loss Second Lien RMBS (Details) (RMBS [Member], United States [Member])	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Expected period until final CDR	34 months	[1]	34 months	[1]	36 months	[1]
Final CPR			10.00%	[1],[2]	10.00%	[1],[2]
Loss severity			98.00%	[1]	98.00%	[1]
HELOCs [Member] | Minimum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	2.80%	[1]	2.30%	[1]	3.80%	[1]
Final CDR trended down to	0.50%	[1]	0.40%	[1]	0.40%	[1]
Initial CPR	6.90%	[1]	2.70%	[1]	2.90%	[1]
Final CPR	15.00%	[1],[2]
Loss severity	90.00%	[1]
HELOCs [Member] | Maximum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	6.80%	[1]	7.70%	[1]	15.90%	[1]
Final CDR trended down to	3.20%	[1]	3.20%	[1]	3.20%	[1]
Initial CPR	21.80%	[1]	21.50%	[1]	15.40%	[1]
Final CPR	21.80%	[1],[2]
Loss severity	98.00%	[1]
HELOCs [Member] | Weighted Average [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	4.10%	[1]	4.90%	[1]	8.80%	[1]
Final CDR trended down to	1.20%	[1]	1.10%	[1]	1.20%	[1]
Initial CPR	11.00%	[1]	9.90%	[1]	6.60%	[1]
Final CPR	15.50%	[1],[2]
Loss severity	90.40%	[1]
Closed-end [Member]
Schedule of Expected Losses to be Paid [Line Items]
Expected period until final CDR	34 months	[1]	34 months	[1]	36 months	[1]
Final CPR	15.00%	[1],[2]	10.00%	[1],[2]	10.00%	[1],[2]
Loss severity	98.00%	[1]	98.00%	[1]	98.00%	[1]
Closed-end [Member] | Minimum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	5.50%	[1]	7.30%	[1]	7.30%	[1]
Final CDR trended down to	3.50%	[1]	3.50%	[1]	3.50%	[1]
Initial CPR	2.80%	[1]	3.10%	[1]	1.90%	[1]
Closed-end [Member] | Maximum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	12.50%	[1]	15.10%	[1]	20.70%	[1]
Final CDR trended down to	9.10%	[1]	9.10%	[1]	9.10%	[1]
Initial CPR	13.90%	[1]	12.00%	[1]	12.50%	[1]
Closed-end [Member] | Weighted Average [Member]
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	7.20%	[1]	8.50%	[1]	12.70%	[1]
Final CDR trended down to	4.90%	[1]	5.00%	[1]	4.90%	[1]
Initial CPR	9.90%	[1]	7.10%	[1]	4.00%	[1]
[1]	Represents variables for most heavily weighted scenario (the “base case”).
[2]	For transactions where the initial CPR is higher than the final CPR, the initial CPR is held constant and the final CPR is not used.

Expected_Loss_to_be_Paid_Compo

Expected Loss to be Paid - Components of Development and Accretion Amounts of Estimated Recoveries (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Expected Losses [Abstract]
Inclusion or removal of deals with breaches of R&W during period	$0	$6
Change in recovery assumptions as the result of recovery success	31	-6
Estimated increase (decrease) in defaults that will result in additional (lower) breaches	-37	-8
Settlements and anticipated settlements	263	289
Accretion of discount on balance	11	15
Total	$268	$296

Expected_Loss_to_be_Paid_Narra

Expected Loss to be Paid - Narrative (Details) (USD $)	12 Months Ended				3 Months Ended			12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2014		Sep. 30, 2014	Dec. 31, 2012		Sep. 12, 2014	Oct. 10, 2013	6-May-13	Apr. 14, 2011	8-May-12
	risk		risk							Transaction	Transaction
Schedule of Expected Losses to be Paid [Line Items]
Number of risks subject to R&W recovery	29		42		29
Risks subject to R&W recovery, related net debt service amount	$2,100,000,000		$5,000,000,000		$2,100,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss	1,169,000,000		982,000,000		1,169,000,000			677,000,000
Economic loss development after recoveries for R&W	30,000,000		-56,000,000
Loss and loss adjustment expense reserve	799,000,000		592,000,000		799,000,000
Net par amount outstanding	403,729,000,000	[1]	459,107,000,000	[2]	403,729,000,000	[1]
Gross par outstanding	426,704,000,000		487,895,000,000		426,704,000,000
Assets	14,925,000,000		16,287,000,000		14,925,000,000
Minimum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Discount factor (as a percent)	0.00%		0.00%
Maximum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Discount factor (as a percent)	2.95%		4.44%
United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	363,294,000,000				363,294,000,000
Puerto Rico [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	4,939,000,000		5,441,000,000		4,939,000,000
Gross par outstanding	6,035,000,000		6,796,000,000		6,035,000,000
RMBS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Amount of liabilities agreed to be paid by entities providing R&W for transaction in which the Company provided insurance	4,200,000,000				4,200,000,000
RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Maximum number of payments behind to be considered performing borrower	1
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates	317,000,000	[3]	712,000,000		317,000,000	[3]		1,370,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss	584,000,000		493,000,000		584,000,000			282,000,000
Economic loss development after recoveries for R&W	268,000,000		156,000,000
Net par amount outstanding	9,417,000,000		13,721,000,000		9,417,000,000
RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	15.00%	[4]	15.00%	[4]	15.00%	[4]		15.00%	[4]
RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	15.00%	[4],[5]	15.00%	[4],[5]	15.00%	[4],[5]		15.00%	[4],[5]
RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	15.00%	[4]	15.00%	[4]	15.00%	[4]		15.00%	[4]
RMBS [Member] | United States [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR			10.00%	[4],[5]				10.00%	[4],[5]
RMBS [Member] | United States [Member] | Closed-end [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	15.00%	[4],[5]	10.00%	[4],[5]	15.00%	[4],[5]		10.00%	[4],[5]
RMBS [Member] | United States [Member] | Minimum [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	15.00%	[4],[5]			15.00%	[4],[5]
RMBS [Member] | United States [Member] | Maximum [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	21.80%	[4],[5]			21.80%	[4],[5]
HELOCs [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Initial period for which borrower can pay only interest payments	10 years
Percentage of expected default loans reaching amortization period	7.50%
TruPS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	4,300,000,000				4,300,000,000
Percentage of installment premiums denominated in currencies other than the U.S. dollar	72.00%
Liability for unpaid claims and claims adjustment expense, net largest single loss	23,000,000		51,000,000		23,000,000			27,000,000
Economic loss development after recoveries for R&W	28,000,000		-7,000,000
Net par amount outstanding	4,326,000,000		4,970,000,000		4,326,000,000
Life Insurance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	3,100,000,000				3,100,000,000
Economic loss development after recoveries for R&W	-93,000,000
Manufactured Housing Loans [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	223,000,000				223,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss	25,000,000				25,000,000
Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	2,500,000,000				2,500,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss	83,000,000				83,000,000
Economic loss development after recoveries for R&W	-18,000,000
Asset-backed Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	1,800,000,000				1,800,000,000
Public Finance Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	700,000,000				700,000,000
Public Finance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	353,482,000,000		386,179,000,000		353,482,000,000
Gross par outstanding	373,360,000,000		409,890,000,000		373,360,000,000
Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss	303,000,000		264,000,000		303,000,000			7,000,000
Economic loss development after recoveries for R&W	-183,000,000		-239,000,000
Net par amount outstanding	322,123,000,000	[1]	352,181,000,000	[2]	322,123,000,000	[1]
Gross par outstanding	334,906,000,000		367,616,000,000		334,906,000,000
Public Finance [Member] | United States [Member] | General obligation [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	140,276,000,000		155,277,000,000		140,276,000,000
Gross par outstanding	144,714,000,000		160,751,000,000		144,714,000,000
Public Finance [Member] | Puerto Rico [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	4,900,000,000				4,900,000,000
Public Finance Stockton General Fund [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	117,000,000				117,000,000
Non-Infrastructure Public Finance [Member] | Spain [Member] | Sovereign and Sub Sovereign [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	374,000,000				374,000,000
Gross par outstanding	521,000,000				521,000,000
Non-Infrastructure Public Finance [Member] | Portugal [Member] | Sovereign and Sub Sovereign [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	102,000,000				102,000,000
Gross par outstanding	114,000,000				114,000,000
Non-Infrastructure Public Finance [Member] | Hungary [Member] | Sovereign and Sub Sovereign [Member]
Schedule of Expected Losses to be Paid [Line Items]
Gross par outstanding	529,000,000				529,000,000
Non-Infrastructure Public Finance [Member] | Spain, Hungry and Portugal [Member] | Sovereign and Sub Sovereign [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss	45,000,000				45,000,000
Economic loss development after recoveries for R&W	-5,000,000
Deutsche Bank [Member]
Schedule of Expected Losses to be Paid [Line Items]
Assets held under trust for reimbursement payment	77,000,000				77,000,000
Number of transactions terminated	1				1					2	1
Number of transactions insured	8				8
City of Detroit [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	2,000,000,000				2,000,000,000
City of Detroit [Member] | Public Finance [Member] | United States [Member] | Sewer [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	1,000,000,000				1,000,000,000
City of Detroit [Member] | Public Finance [Member] | United States [Member] | Water Sector [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	878,000,000				878,000,000
City of Detroit [Member] | Public Finance [Member] | United States [Member] | Water and Sewer [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	1,800,000,000				1,800,000,000
Bonds sold in tender offer, amount	677,000,000				677,000,000
Remaining principle amount after tender offer	841,000,000				841,000,000
Michigan Finance Authority [Member] | Public Finance [Member] | United States [Member] | General obligation [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	107,000,000				107,000,000
Louisville Arena Authority [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	336,000,000				336,000,000
BIG [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	18,247,000,000		22,538,000,000		18,247,000,000
BIG [Member] | Puerto Rico [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	4,670,000,000				4,670,000,000
BIG [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	5,643,000,000		7,717,000,000		5,643,000,000
BIG [Member] | TruPS [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	1,300,000,000				1,300,000,000
Net par amount outstanding	1,333,000,000		1,722,000,000		1,333,000,000
BIG [Member] | Life Insurance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Liability for unpaid claims and claims adjustment expense, net largest single loss	161,000,000				161,000,000
Loss and loss adjustment expense reserve	598,000,000				598,000,000
BIG [Member] | Manufactured Housing Loans [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	160,000,000				160,000,000
BIG [Member] | Asset-backed Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	196,000,000				196,000,000
BIG [Member] | Public Finance Student Loan [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	101,000,000				101,000,000
BIG [Member] | Public Finance [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	7,850,000,000		9,094,000,000		7,850,000,000
BIG [Member] | Public Finance [Member] | Puerto Rico [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	4,700,000,000				4,700,000,000
BIG [Member] | Non-Infrastructure Public Finance [Member] | Hungary [Member] | Sovereign and Sub Sovereign [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	499,000,000				499,000,000
BIG [Member] | Ballantyne Re Plc and Orkney Re I I Plc [Member] | Life Insurance [Member]
Schedule of Expected Losses to be Paid [Line Items]
Number of transactions insured	2				2
Refinancing Risk on Infrastructure Transactions [Member]
Schedule of Expected Losses to be Paid [Line Items]
Financial guaranty insurance contracts, principal amount	3,000,000,000				3,000,000,000
Financial insurance guaranty, infrastructure finance, possible claims requiring payment, gross before reinsurance	1,800,000,000				1,800,000,000
Refinancing Risk on Infrastructure Transactions [Member] | Minimum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated years for recoveries of infrastructure transactions	10 years
Refinancing Risk on Infrastructure Transactions [Member] | Maximum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated years for recoveries of infrastructure transactions	35 years
First Lien [Member] | RMBS [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Number of transactions terminated	3				3
First Lien [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Increase of expected losses from estimated impact of refinements in assumptions	42,000,000		8,000,000		13,000,000		36,000,000
Default estimate liquidation period			3 years					2 years
Number of delinquent payments			2
Projected loss assumptions, CDR, plateau rate, projection period	36 months
Projected loss assumptions, Final CDR, Period for voluntary prepayments to continue	12 months
CDR, change from initial assumption	12 months
Intermediate conditional default rate (as a percent)	5.00%				5.00%
Number of scenarios weighted in estimating expected losses	5
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates	232,000,000	[3]	569,000,000		232,000,000	[3]		1,082,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss	595,000,000		620,000,000		595,000,000			432,000,000
Economic loss development after recoveries for R&W	226,000,000		71,000,000
First Lien [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates	15,000,000	[3]	173,000,000		15,000,000	[3]		591,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss	-16,000,000		-9,000,000		-16,000,000			-131,000,000
Economic loss development after recoveries for R&W	59,000,000		98,000,000
Net par amount outstanding	407,000,000		937,000,000		407,000,000
First Lien [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates	109,000,000	[3]	118,000,000		109,000,000	[3]		109,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss	303,000,000		304,000,000		303,000,000			242,000,000
Economic loss development after recoveries for R&W	7,000,000		-92,000,000
Net par amount outstanding	4,051,000,000		6,130,000,000		4,051,000,000
First Lien [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates	2,000,000	[3]	4,000,000		2,000,000	[3]		4,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss	4,000,000		21,000,000		4,000,000			6,000,000
Economic loss development after recoveries for R&W	16,000,000		-16,000,000
Net par amount outstanding	471,000,000		541,000,000		471,000,000
First Lien [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates	106,000,000	[3]	274,000,000		106,000,000	[3]		378,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss	304,000,000		304,000,000		304,000,000			315,000,000
Economic loss development after recoveries for R&W	144,000,000		81,000,000
Net par amount outstanding	2,532,000,000		3,590,000,000		2,532,000,000
First Lien [Member] | Base Scenario [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, CDR, plateau rate, projection period	36 months
Period from plateau to intermediate conditional default rate (in months)	12 months
Period of constant intermediate conditional default rate (in months)	36 months
Intermediate conditional default rate as a percentage of plateau conditional default rate	20.00%
Final conditional default rate as a percentage of plateau conditional default rate	5.00%
Final conditional default rate, shortened term	6 months
Period for which estimated defaults are attributed to loans currently delinquent or in foreclosure	36 months
Projected loss assumptions, loss severity, subsequent period	18 months
Estimated loss severity rate, one through six months (as a percent)	18 months
Loss severity (as a percent)	40.00%				40.00%
Projected loss assumptions, period to reach final loss severity rate	2 years 6 months
Projected loss assumptions, Final CDR, Period for voluntary prepayments to continue	8 years 6 months
Current conditional prepayment rate used in alternate scenario for loss estimate (as a percent)	15.00%				15.00%
First Lien [Member] | Somewhat Stressful Environment [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, CDR, plateau rate, projection period	42 months
Projected loss assumptions, period to reach final loss severity rate	4 years 6 months
Increase in the plateau period used to calculate potential change in loss estimate (in months)	6 months
Projected loss assumptions, prior period to reach final loss severity rate	2 years 6 months
First Lien [Member] | Somewhat Stressful Environment [Member] | RMBS [Member] | United States [Member] | Option Adjustable Rate Mortgage and Alt-A Mortgage [Member]
Schedule of Expected Losses to be Paid [Line Items]
Loss severity (as a percent)	45.00%				45.00%
First Lien [Member] | Somewhat Stressful Environment [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	9,000,000
First Lien [Member] | Somewhat Stressful Environment [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	73,000,000
First Lien [Member] | Somewhat Stressful Environment [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	2,000,000
First Lien [Member] | Somewhat Stressful Environment [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	29,000,000
First Lien [Member] | Somewhat Stressful Environment [Member] | Subprime [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Loss severity (as a percent)	60.00%				60.00%
First Lien [Member] | Somewhat Stressful Environment [Member] | Alt-A [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Loss severity (as a percent)	45.00%				45.00%
First Lien [Member] | More Stressful Environment [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Period from plateau to intermediate conditional default rate (in months)	15 months
Projected loss assumptions, period to reach final loss severity rate	9 years
First Lien [Member] | More Stressful Environment [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	21,000,000
First Lien [Member] | More Stressful Environment [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	102,000,000
First Lien [Member] | More Stressful Environment [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	7,000,000
First Lien [Member] | More Stressful Environment [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	79,000,000
First Lien [Member] | Somewhat Less Stressful Environment [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	12,000,000
First Lien [Member] | Somewhat Less Stressful Environment [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	10,000,000
First Lien [Member] | Somewhat Less Stressful Environment [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	100,000
First Lien [Member] | Somewhat Less Stressful Environment [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	-300,000
First Lien [Member] | Least Stressful Environment [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, CDR, plateau rate, projection period	30 months
Period from plateau to intermediate conditional default rate (in months)	9 months
Decrease in the plateau period used to calculate potential change in loss estimate (in months)	6 months
First Lien [Member] | Least Stressful Environment [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	-26,000,000
First Lien [Member] | Least Stressful Environment [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	-52,000,000
First Lien [Member] | Least Stressful Environment [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	-1,000,000
First Lien [Member] | Least Stressful Environment [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, increase (decrease) in expected loss to be paid, net	-28,000,000
First Lien [Member] | Bank of America [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Collateral losses	4,100,000,000				4,100,000,000
First Lien [Member] | Bank of America [Member] | Base Scenario [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Collateral losses	5,100,000,000				5,100,000,000
First Lien [Member] | UBS [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Agreed reimbursement of R&W, percentage												85.00%
Assets held under trust for reimbursement payment	109,000,000				109,000,000
First Lien [Member] | BIG [Member] | RMBS [Member] | United States [Member] | Option ARM [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	183,000,000		598,000,000		183,000,000
First Lien [Member] | BIG [Member] | RMBS [Member] | United States [Member] | Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	1,575,000,000		1,945,000,000		1,575,000,000
First Lien [Member] | BIG [Member] | RMBS [Member] | United States [Member] | Prime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	353,000,000		403,000,000		353,000,000
First Lien [Member] | BIG [Member] | RMBS [Member] | United States [Member] | Alt-A [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	1,841,000,000		2,728,000,000		1,841,000,000
Second Lien [Member] | Closed-end [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	15.00%				15.00%
Second Lien [Member] | RMBS [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	15.00%				15.00%
Second Lien [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Period company reduced base scenario			2 months
Period company reduced optimistic scenario			3 months
Period from plateau to intermediate conditional default rate (in months)	28 months		28 months
CDR, change from initial assumption								2 months
Period of loan default estimate	5 months
Number of preceding months average liquidation rates used to estimate loan default rate	12 months
Number of months CDR is calculated by applying liquidation rates to past due balances	4 months
Stress period (in months)			34 months
Number of months of delinquent data			5 months
Period of constant conditional default rate (in months)			1 month
Conditional prepayment rate base case, average number of quarters	3 months
Number of conditional default rate curves modeled in estimating losses	3
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates	85,000,000	[3]	143,000,000		85,000,000	[3]		288,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss	-11,000,000		-127,000,000		-11,000,000			-150,000,000
Economic loss development after recoveries for R&W	42,000,000		85,000,000
Second Lien [Member] | RMBS [Member] | United States [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	15.00%		10.00%		15.00%
Increase in expected losses due to adjustment in recovery and maximum amortization recognition assumptions	53,000,000
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates	0	[3]	45,000,000		0	[3]		150,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss	-19,000,000		-116,000,000		-19,000,000			-111,000,000
Economic loss development after recoveries for R&W	45,000,000		91,000,000
Net par amount outstanding	1,738,000,000		2,279,000,000		1,738,000,000
Second Lien [Member] | RMBS [Member] | United States [Member] | Closed-end [Member]
Schedule of Expected Losses to be Paid [Line Items]
Estimated benefit from loan repurchases related to breaches of R&W included in net expected loss estimates	85,000,000	[3]	98,000,000		85,000,000	[3]		138,000,000
Liability for unpaid claims and claims adjustment expense, net largest single loss	8,000,000		-11,000,000		8,000,000			-39,000,000
Economic loss development after recoveries for R&W	-3,000,000		-6,000,000
Net par amount outstanding	218,000,000		244,000,000		218,000,000
Second Lien [Member] | RMBS [Member] | United States [Member] | Home Equity Line of Credit and Closed-end Mortgage [Member]
Schedule of Expected Losses to be Paid [Line Items]
Final CPR	15.00%				15.00%
Second Lien [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Loss recovery assumption (as a percent)	10.00%		2.00%		10.00%
Second Lien [Member] | Base Scenario [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Period from plateau to intermediate conditional default rate (in months)	28 months
Stress period (in months)	34 months
Period of constant conditional default rate (in months)	1 month
Second Lien [Member] | Base Scenario One [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Projected loss assumptions, CDR, plateau rate, projection period	4 months
Period from plateau to intermediate conditional default rate (in months)	33 months
Stress period (in months)	42 months
Increase in conditional default rate ramp down period	5 months
Second Lien [Member] | Base Scenario One [Member] | RMBS [Member] | United States [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Change in estimate for increased conditional default rate plateau period	14,000,000
Second Lien [Member] | Base Scenario One [Member] | RMBS [Member] | United States [Member] | Closed-end [Member]
Schedule of Expected Losses to be Paid [Line Items]
Change in estimate for decreased conditional default rate ramp down period	1,000,000
Second Lien [Member] | Based Scenario Two [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Stress period (in months)	24 months
Period of constant conditional default rate (in months)	1 month
Decreased conditional default rate ramp down period	18 months
Second Lien [Member] | Based Scenario Two [Member] | RMBS [Member] | United States [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Change in estimate for decreased conditional default rate ramp down period	15,000,000
Second Lien [Member] | Based Scenario Two [Member] | RMBS [Member] | United States [Member] | Closed-end [Member]
Schedule of Expected Losses to be Paid [Line Items]
Change in estimate for decreased conditional default rate ramp down period	1,000,000
Second Lien [Member] | Bank of America [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Agreed reimbursement of R&W, percentage													80.00%
Maximum loss up to which loss sharing percentage applicable													6,600,000,000
Second Lien [Member] | Bank of America [Member] | Base Scenario [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Assets held under trust for reimbursement payment	574,000,000				574,000,000
Second Lien [Member] | Guarantor Obligations, Group One [Member] | Deutsche Bank [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Maximum aggregate collateral losses up to which first layer of loss sharing will be applicable	319,000,000				319,000,000									319,000,000
Loss sharing percentage, first layer														80.00%
Second Lien [Member] | Guarantor Obligations, Group Two [Member] | Deutsche Bank [Member] | RMBS [Member] | United States [Member]
Schedule of Expected Losses to be Paid [Line Items]
Maximum aggregate collateral losses up to which first layer of loss sharing will be applicable														389,000,000
Loss sharing percentage, first layer														85.00%
Second Lien [Member] | Guarantor Obligations, Group Two [Member] | Deutsche Bank [Member] | RMBS [Member] | United States [Member] | Maximum [Member]
Schedule of Expected Losses to be Paid [Line Items]
Maximum aggregate collateral losses up to which first layer of loss sharing will be applicable														600,000,000
Second Lien [Member] | BIG [Member] | RMBS [Member] | United States [Member] | HELOCs [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	1,557,000,000		1,897,000,000		1,557,000,000
Second Lien [Member] | BIG [Member] | RMBS [Member] | United States [Member] | Closed-end [Member]
Schedule of Expected Losses to be Paid [Line Items]
Net par amount outstanding	$134,000,000		$146,000,000		$134,000,000
[1]	Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.
[2]	Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of December 31, 2013, which are primarily in the BIG category.
[3]	See the section "Breaches of Representations and Warranties" below for eligible assets held in trust.
[4]	Represents variables for most heavily weighted scenario (the “base case”).
[5]	For transactions where the initial CPR is higher than the final CPR, the initial CPR is held constant and the final CPR is not used.

Financial_Guaranty_Insurance_L2

Financial Guaranty Insurance Losses - Loss and LAE Reserve and Salvage and Subrogation Recoverable Net of Reinsurance (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	$721	[1]	$556	[1]
Salvage and Subrogation Recoverable, net	154	[1]	170	[1]
Net Reserve (Recoverable)	567	[1]	386	[1]
Financial Guarantee Insurance Product Line [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	719		554
Salvage and Subrogation Recoverable, net	148		165
Net Reserve (Recoverable)	571		389
Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	799		657
Salvage and Subrogation Recoverable, net	149		250
Net Reserve (Recoverable)	650		407
Financial Guarantee Insurance Product Line [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	80		103
Salvage and Subrogation Recoverable, net	1		85
Net Reserve (Recoverable)	79		18
Other Insurance Product Line [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	2		2
Salvage and Subrogation Recoverable, net	6		5
Net Reserve (Recoverable)	-4		-3
TruPS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	0		2
Salvage and Subrogation Recoverable, net	0		0
Net Reserve (Recoverable)	0		2
Structured Finance [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	236		145
Salvage and Subrogation Recoverable, net	2		6
Net Reserve (Recoverable)	234		139
Financial Guarantee [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	799		657
Salvage and Subrogation Recoverable, net	136		235
Net Reserve (Recoverable)	663		422
Other [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	0		0
Salvage and Subrogation Recoverable, net	13		15
Net Reserve (Recoverable)	-13		-15
United States [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	290		286
Salvage and Subrogation Recoverable, net	126		221
Net Reserve (Recoverable)	164		65
United States [Member] | Public Finance [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	243		189
Salvage and Subrogation Recoverable, net	8		8
Net Reserve (Recoverable)	235		181
Non United States [Member] | Public Finance [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	30		35
Salvage and Subrogation Recoverable, net	0		0
Net Reserve (Recoverable)	30		35
First Lien [Member] | United States [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	283		276
Salvage and Subrogation Recoverable, net	48		49
Net Reserve (Recoverable)	235		227
Second Lien [Member] | United States [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	7		10
Salvage and Subrogation Recoverable, net	78		172
Net Reserve (Recoverable)	-71		-162
Prime [Member] | First Lien [Member] | United States [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	2		3
Salvage and Subrogation Recoverable, net	0		0
Net Reserve (Recoverable)	2		3
Alt-A [Member] | First Lien [Member] | United States [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	87		108
Salvage and Subrogation Recoverable, net	0		0
Net Reserve (Recoverable)	87		108
Option ARM [Member] | First Lien [Member] | United States [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	28		22
Salvage and Subrogation Recoverable, net	40		47
Net Reserve (Recoverable)	-12		-25
Subprime [Member] | First Lien [Member] | United States [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	166		143
Salvage and Subrogation Recoverable, net	8		2
Net Reserve (Recoverable)	158		141
Closed-end [Member] | Second Lien [Member] | United States [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	4		5
Salvage and Subrogation Recoverable, net	39		45
Net Reserve (Recoverable)	-35		-40
HELOCs [Member] | Second Lien [Member] | United States [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE Reserve, net	3		5
Salvage and Subrogation Recoverable, net	39		127
Net Reserve (Recoverable)	($36)		($122)
[1]	See “Components of Net Reserves (Salvage)” table for loss and LAE reserve and salvage and subrogation recoverable components.

Financial_Guaranty_Insurance_L3

Financial Guaranty Insurance Losses - Components of Net Reserves (Salvage) Insurance Contracts (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE reserve	$799		$592
Reinsurance recoverable on unpaid losses	-78		-36
Loss and LAE reserve, net	721	[1]	556	[1]
Salvage and subrogation recoverable	-151		-174
Salvage and subrogation payable	10	[2]	19	[2]
Other recoveries	-13	[3]	-15	[3]
Salvage and subrogation recoverable, net and other recoverable	-154		-170
Net reserves (salvage) - financial guaranty	567		386
Other Insurance Product Line [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE reserve, net	2		2
Net reserves (salvage) - financial guaranty	-4		-3
Financial Guarantee Insurance Product Line [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE reserve, net	719		554
Other recoveries	-13	[3]
Net reserves (salvage) - financial guaranty	$571		$389
[1]	See “Components of Net Reserves (Salvage)” table for loss and LAE reserve and salvage and subrogation recoverable components.
[2]	Recorded as a component of reinsurance balances payable.
[3]	R&W recoverables recorded in other assets on the consolidated balance sheet.

Financial_Guaranty_Insurance_L4

Financial Guaranty Insurance Losses - Balance Sheet Classification of Net Expected Recoveries for Breaches of R&W Insurance Contracts (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Salvage and subrogation recoverable, net [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Net expected recoveries for breaches of R&W insurance contracts	$20	[1]	$73	[1]
Salvage and subrogation recoverable, net [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Net expected recoveries for breaches of R&W insurance contracts	0		-49
Loss and LAE reserve, net [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Net expected recoveries for breaches of R&W insurance contracts	177	[1]	339	[1]
Loss and LAE reserve, net [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Net expected recoveries for breaches of R&W insurance contracts	-8		-24
Financial Guarantee Insurance Product Line [Member] | Salvage and subrogation recoverable, net [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Net expected recoveries for breaches of R&W insurance contracts	20		122
Financial Guarantee Insurance Product Line [Member] | Loss and LAE reserve, net [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Net expected recoveries for breaches of R&W insurance contracts	$185		$363
[1]	The remaining benefit for R&W is either recorded at fair value in FG VIE assets, or not recorded on the balance sheet until the total loss, net of R&W, exceeds unearned premium reserve.

Financial_Guaranty_Insurance_L5

Financial Guaranty Insurance Losses - Reconciliation of Net Expected Loss to be Paid and Expensed (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
In Millions, unless otherwise specified
Guarantor Obligations [Line Items]
Net expected loss to be paid after recoveries for R&W	$1,169		$982		$677
Loss and LAE reserve, net of reinsurance	721	[1]	556	[1]
Other recoveries	13	[2]	15	[2]
Net expected loss to be expensed (present value)	318
Variable Interest Entity, Primary Beneficiary [Member]
Guarantor Obligations [Line Items]
Net expected loss to be expensed (present value)	89
Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Guarantor Obligations [Line Items]
Contra-paid, net	-100	[3],[4]	39	[3],[4]
Financial Guarantee Insurance Product Line [Member]
Guarantor Obligations [Line Items]
Net expected loss to be paid after recoveries for R&W	989
Contra-paid, net	-100
Salvage and subrogation recoverable, net of reinsurance	135
Loss and LAE reserve, net of reinsurance	719		554
Other recoveries	13	[2]
Net expected loss to be expensed (present value)	318	[5]
Financial Guarantee Insurance Product Line [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Guarantor Obligations [Line Items]
Loss and LAE reserve, net of reinsurance	80		103
Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Guarantor Obligations [Line Items]
Net expected loss to be paid after recoveries for R&W	1,115
Loss and LAE reserve, net of reinsurance	799		657
Financial Guarantee Insurance Product Line [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Guarantor Obligations [Line Items]
Net expected loss to be paid after recoveries for R&W	$126
[1]	See “Components of Net Reserves (Salvage)” table for loss and LAE reserve and salvage and subrogation recoverable components.
[2]	R&W recoverables recorded in other assets on the consolidated balance sheet.
[3]	See Note 7, "Financial Guaranty Insurance Losses– Insurance Contracts' Loss Information" for an explanation of "contra-paid".
[4]	Excludes $125 million and $187 million deferred premium revenue and $42 million and $55 million of contra-paid related to FG VIEs as of December 31, 2014 and December 31, 2013, respectively.
[5]	Excludes $89 million as of December 31, 2014 related to consolidated FG VIEs.

Financial_Guaranty_Insurance_L6

Financial Guaranty Insurance Losses - Net Expected Loss to be Expensed Insurance Contracts (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Financial Guaranty Insurance Contracts, Premiums [Line Items]
2015 (January 1 – March 31)	$8
2015 (April 1 – June 30)	8
2015 (July 1 – September 30)	8
2015 (October 1 – December 31)	9
Subtotal 2015	33
2016	34
2017	27
2018	24
2019	22
2020-2024	79
2025-2029	46
2030-2034	32
After 2034	21
Net expected loss to be expensed	318
Discount	413
Total future value	$731

Financial_Guaranty_Insurance_L7

Financial Guaranty Insurance Losses - Loss and LAE Reported on the Statements of Operations (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE	$72	($44)	$57	$41	$85	$55	$62	($48)	$126	$154	$504
Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									156	175	569
Variable Interest Entity, Primary Beneficiary [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									-30	-21	-65
Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									157	175	586
Other Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									-1	0	-17
RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | United States [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									-129	-4	308
TruPS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									-1	-1	-10
Other structured finance [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									96	-34	3
Structured Finance [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									-34	-39	301
Public Finance [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									191	214	285
Public Finance [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | United States [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									192	198	51
Public Finance [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | Non United States [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									-1	16	234
First Lien [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | United States [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									-96	31	228
Second Lien [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | United States [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									-33	-35	80
Prime [Member] | First Lien [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | United States [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									-1	1	2
Alt-A [Member] | First Lien [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | United States [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									-66	-2	51
Option ARM [Member] | First Lien [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | United States [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									-37	-48	137
Subprime [Member] | First Lien [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | United States [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									8	80	38
Closed-end [Member] | Second Lien [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | United States [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									-2	18	31
HELOCs [Member] | Second Lien [Member] | RMBS [Member] | Financial Guarantee Insurance Product Line [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | United States [Member]
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items]
Loss and LAE									($31)	($53)	$49

Financial_Guaranty_Insurance_L8

Financial Guaranty Insurance Losses - BIG Transaction Loss Summary (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
	risk		risk
Discount
Total	($413)
Reserves (salvage)
Total	567		386
BIG [Member]
Number of risks
Total (in contracts)	358	[1]	384	[1]
Remaining weighted average contract period
Total (in years)	10 years 3 months 18 days		10 years 6 months
Principal
Total	15,222		17,745
Interest
Total	7,651		9,290
Total net outstanding exposure
Total	22,873	[2]	27,035	[2]
Expected cash outflows (inflows)
Total	3,118		3,252
Potential recoveries
Total, Undiscounted R&W	-239		-568
Total, Other	-1,477		-1,537	[3]
Total	-1,716	[3]	-2,105
Subtotal
Total	1,402		1,147
Discount
Total	-413		-406
Present value of expected cash flows
Net expected loss to be paid	989		741
Deferred premium revenue
Total	584		681
Reserves (salvage)
Total	571	[4]	389	[4]
BIG [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member]
Number of risks
Total (in contracts)	358	[1]	384	[1]
Remaining weighted average contract period
Total (in years)	10 years 3 months 18 days		10 years 6 months
Principal
Total	15,222		17,745
Interest
Total	7,651		9,290
Total net outstanding exposure
Total	22,873	[2]	27,035	[2]
Expected cash outflows (inflows)
Total	3,463		3,942
Potential recoveries
Total, Undiscounted R&W	-247		-640
Total, Other	-1,654		-2,044	[3]
Total	-1,901	[3]	-2,684
Subtotal
Total	1,562		1,258
Discount
Total	-447		-457
Present value of expected cash flows
Net expected loss to be paid	1,115		801
Deferred premium revenue
Total	700		859
Reserves (salvage)
Total	650	[4]	407	[4]
BIG [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | BIG 1 [Member]
Number of risks
Ceded (in contracts)	-59	[1]	-72	[1]
Total (in contracts)	164	[1]	185	[1]
Remaining weighted average contract period
Gross (in years)	9 years 10 months 24 days		10 years 6 months
Ceded (in years)	7 years 4 months 24 days		8 years 1 month
Principal
Gross	12,358		15,132
Ceded	-2,163		-2,741
Interest
Gross	6,350		8,114
Ceded	-838		-1,144
Total net outstanding exposure
Gross	18,708	[2]	23,246	[2]
Ceded	-3,001	[2]	-3,885	[2]
Expected cash outflows (inflows)
Gross	1,762		1,853
Ceded	-626		-528
Total	39		-13
Potential recoveries
Gross, Undiscounted R&W	-39		-105
Ceded, Undiscounted R&W	0		1
Gross, Other	-1,687		-1,774	[3]
Ceded, Other	608		513	[3]
Ceded	608		514
Gross	-1,726		-1,879
Subtotal
Gross	36		-26
Ceded	-18		-14
Discount
Gross	3		13
Ceded	0		0
Present value of expected cash flows
Ceded	-18		-14
Deferred premium revenue
Gross	378		517
Ceded	-70		-90
Reserves (salvage)
Gross	-42	[4]	-114	[4]
Ceded	-5	[4]	1	[4]
BIG [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | BIG 2 [Member]
Number of risks
Ceded (in contracts)	-15	[1]	-24	[1]
Total (in contracts)	75	[1]	80	[1]
Remaining weighted average contract period
Gross (in years)	10 years 1 month 6 days		8 years 3 months
Ceded (in years)	8 years 10 months 24 days		5 years 11 months
Principal
Gross	2,421		2,483
Ceded	-286		-160
Interest
Gross	1,274		1,181
Ceded	-121		-53
Total net outstanding exposure
Gross	3,695	[2]	3,664	[2]
Ceded	-407	[2]	-213	[2]
Expected cash outflows (inflows)
Gross	763		1,038
Ceded	-77		-40
Total	392		241
Potential recoveries
Gross, Undiscounted R&W	-48		-201
Ceded, Undiscounted R&W	2		8
Gross, Other	-206		-470	[3]
Ceded, Other	5		19	[3]
Ceded	7		27
Gross	-254		-671
Subtotal
Gross	509		367
Ceded	-70		-13
Discount
Gross	-117		-126
Ceded	11		3
Present value of expected cash flows
Ceded	-59		-10
Deferred premium revenue
Gross	119		163
Ceded	-6		-7
Reserves (salvage)
Gross	278	[4]	117	[4]
Ceded	-53	[4]	-4	[4]
BIG [Member] | Consolidated Entity Excluding Consolidation of Variable Interest Entities (VIE) [Member] | BIG 3 [Member]
Number of risks
Ceded (in contracts)	-38	[1]	-34	[1]
Total (in contracts)	119	[1]	119	[1]
Remaining weighted average contract period
Gross (in years)	9 years 7 months 6 days		9 years 9 months
Ceded (in years)	6 years 10 months 24 days		7 years 2 months
Principal
Gross	3,067		3,189
Ceded	-175		-158
Interest
Gross	1,034		1,244
Ceded	-48		-52
Total net outstanding exposure
Gross	4,101	[2]	4,433	[2]
Ceded	-223	[2]	-210	[2]
Expected cash outflows (inflows)
Gross	1,716		1,681
Ceded	-75		-62
Total	788		622
Potential recoveries
Gross, Undiscounted R&W	-171		-356
Ceded, Undiscounted R&W	9		13
Gross, Other	-404		-351	[3]
Ceded, Other	30		19	[3]
Ceded	39		32
Gross	-575		-707
Subtotal
Gross	1,141		974
Ceded	-36		-30
Discount
Gross	-353		-352
Ceded	9		5
Present value of expected cash flows
Ceded	-27		-25
Deferred premium revenue
Gross	312		303
Ceded	-33		-27
Reserves (salvage)
Gross	482	[4]	420	[4]
Ceded	-10	[4]	-13	[4]
BIG [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Expected cash outflows (inflows)
Total	-345		-690
Potential recoveries
Total, Undiscounted R&W	8		72
Total, Other	177		507	[3]
Total	185		579
Subtotal
Total	-160		-111
Discount
Total	34		51
Present value of expected cash flows
Net expected loss to be paid	-126		-60
Deferred premium revenue
Total	-116		-178
Reserves (salvage)
Total	($79)	[4]	($18)	[4]
[1]	A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments. The ceded number of risks represents the number of risks for which the Company ceded a portion of its exposure.
[2]	Includes BIG amounts related to FG VIEs.
[3]	Includes excess spread and draws on HELOCs.
[4]	See table “Components of net reserves (salvage).”

Financial_Guaranty_Insurance_L9

Financial Guaranty Insurance Losses - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Guarantor Obligations [Line Items]
Financial guaranty insurance expected LAE reserve, amount	12,000,000	27,000,000
Guaranteed investment contract, aggregate accreted balance	2,300,000,000
Assets of GIC issuers, aggregate accreted principal	3,400,000,000
Assets of GIC issuers, aggregate market value	3,100,000,000
Variable rate demand obligations
Guarantor Obligations [Line Items]
Rate basis for bank bond rate	prime rate
Minimum [Member]
Guarantor Obligations [Line Items]
Weighted average risk-free rates for U.S. dollar denominated financial guaranty insurance obligations	0.00%	0.00%
Minimum [Member] | Variable rate demand obligations
Guarantor Obligations [Line Items]
Bank bond rate (as a percent)	2.00%
Threshold period of bonds held by bank for right of accelerated repayment (in days)	90 days
Maximum [Member]
Guarantor Obligations [Line Items]
Weighted average risk-free rates for U.S. dollar denominated financial guaranty insurance obligations	2.95%	4.44%
Maximum [Member] | Variable rate demand obligations
Guarantor Obligations [Line Items]
Bank bond rate (as a percent)	3.00%
Bank bond capped rate (as a percent)	25.00%
Threshold period of bonds held by bank for right of accelerated repayment (in days)	180 days
Cash | Minimum [Member]
Guarantor Obligations [Line Items]
Collateralization as a percentage of GIC balance	100.00%
Asset-backed Securities [Member] | Maximum [Member]
Guarantor Obligations [Line Items]
Collateralization as a percentage of GIC balance	108.00%
Termination of Swap Obligation due to Rating Downgrade [Member] | AGM [Member]
Guarantor Obligations [Line Items]
Maximum possible estimated termination payment on swap obligations after taking account the rating downgrade in January 2013	146,000,000
Termination of Swap Obligation due to Further Rating Downgrade [Member] | AGM [Member]
Guarantor Obligations [Line Items]
Maximum possible estimated termination payment on swap obligations after taking account the rating downgrade in January 2013	393,000,000
Financial Guarantee [Member] | AGM and AGC [Member]
Guarantor Obligations [Line Items]
Financial guarantee insurance contracts principal amount insured	6,000,000,000
Internal Credit, B Minus Rating [Member] | Financial Guarantee [Member] | AGM and AGC [Member]
Guarantor Obligations [Line Items]
Financial guarantee insurance contracts principal amount insured	300,000,000

Fair_Value_Measurement_Measure

Fair Value Measurement - Measured and Carried at Fair Value (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Percentage of CDS contracts which are fair valued using minimum premium	21.00%		61.00%
CDS contracts [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Gross spread percentage	100.00%	[1]	100.00%	[1]
Number of sources of credit spread	3
Based on actual collateral specific spreads [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Gross spread percentage	9.00%	[1]	6.00%	[1]
Based on market indices [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Gross spread percentage	82.00%	[1]	88.00%	[1]
Provided by the CDS counterparty [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Gross spread percentage	9.00%	[1]	6.00%	[1]
Scenario 1 [Member] | CDS contracts [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Bank profit as % of total	62.00%
Hedge cost as % of total	16.00%
Premium received per annum as % of total	22.00%
Original gross spread/cash bond price (as a percent)	1.85%
Bank profit (as a percent)	1.15%
Hedge cost (as a percent)	0.30%
The Company premium received per annum (as a percent)	0.40%
Scenario 1 [Member] | CDS contracts [Member] | AGC [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Original gross spread/cash bond price (as a percent)	3.00%
Percentage of exposure hedged	10.00%
Scenario 2 [Member] | CDS contracts [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Bank profit as % of total	10.00%
Hedge cost as % of total	88.00%
Premium received per annum as % of total	2.00%
Original gross spread/cash bond price (as a percent)	5.00%
Bank profit (as a percent)	0.50%
Hedge cost (as a percent)	4.40%
The Company premium received per annum (as a percent)	0.10%
Scenario 2 [Member] | CDS contracts [Member] | AGC [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Original gross spread/cash bond price (as a percent)	17.60%
Percentage of exposure hedged	25.00%
Recurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Other invested assets	95		121
Recurring [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Number of fixed maturity securities valued using model processes	37
Fixed maturity securities	770
Recurring [Member] | Level 3 [Member] | CDS contracts [Member] | Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount factor (as a percent)	0.26%		0.21%
Recurring [Member] | Level 3 [Member] | CDS contracts [Member] | Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount factor (as a percent)	2.70%		3.88%
Available-for-Sale Debt Securities and Short Term Investments [Member] | Recurring [Member] | Level 3 [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Percentage of fixed maturity securities valued using model processes to the Company's fixed-income securities and short-term investments at fair value	7.00%
[1]	Based on par.

Fair_Value_Measurement_Financi

Fair Value Measurement - Financial Instruments Carried at Fair Value (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Assets:
Fixed-maturity securities	$11,258		$10,615
Other invested assets	126		170
Credit derivative assets	68		94
Liabilities:
Credit derivative liabilities	963		1,787
Obligations of state and political subdivisions [Member]
Assets:
Fixed-maturity securities	4,949	[1]	4,554	[1]
Recurring [Member]
Assets:
Other invested assets	100	[2]	127	[2]
Credit derivative assets	68		94
FG VIEs’ assets, at fair value	1,398	[3]	2,565
Other assets	78		84
Total assets carried at fair value	12,902		13,485
Liabilities:
Credit derivative liabilities	963		1,787
FG VIEs’ liabilities with recourse, at fair value	1,277		1,790
FG VIEs’ liabilities without recourse, at fair value	142		1,081
Total liabilities carried at fair value	2,382		4,658
Recurring [Member] | Level 1 [Member]
Assets:
Other invested assets	0	[2]	0	[2]
Credit derivative assets	0		0
FG VIEs’ assets, at fair value	0	[3]	0
Other assets	26		27
Total assets carried at fair value	385		533
Liabilities:
Credit derivative liabilities	0		0
FG VIEs’ liabilities with recourse, at fair value	0		0
FG VIEs’ liabilities without recourse, at fair value	0		0
Total liabilities carried at fair value	0		0
Recurring [Member] | Level 2 [Member]
Assets:
Other invested assets	17	[2]	119	[2]
Credit derivative assets	0		0
FG VIEs’ assets, at fair value	0	[3]	0
Other assets	17		11
Total assets carried at fair value	10,163		9,509
Liabilities:
Credit derivative liabilities	0		0
FG VIEs’ liabilities with recourse, at fair value	0		0
FG VIEs’ liabilities without recourse, at fair value	0		0
Total liabilities carried at fair value	0		0
Recurring [Member] | Level 3 [Member]
Assets:
Other invested assets	83	[2]	8	[2]
Credit derivative assets	68		94
FG VIEs’ assets, at fair value	1,398	[3]	2,565
Other assets	35		46
Total assets carried at fair value	2,354		3,443
Liabilities:
Credit derivative liabilities	963		1,787
FG VIEs’ liabilities with recourse, at fair value	1,277		1,790
FG VIEs’ liabilities without recourse, at fair value	142		1,081
Total liabilities carried at fair value	2,382		4,658
Fixed Maturities [Member]
Assets:
Fixed-maturity securities	10,491		9,711
Fixed Maturities [Member] | Obligations of state and political subdivisions [Member]
Assets:
Fixed-maturity securities	5,795		5,079
Fixed Maturities [Member] | US Treasury and Government [Member]
Assets:
Fixed-maturity securities	665		700
Fixed Maturities [Member] | Corporate securities [Member]
Assets:
Fixed-maturity securities	1,368		1,340
Fixed Maturities [Member] | RMBS [Member]
Assets:
Fixed-maturity securities	1,285	[4]	1,122	[4]
Fixed Maturities [Member] | CMBS [Member]
Assets:
Fixed-maturity securities	659	[4]	549	[4]
Fixed Maturities [Member] | Asset-backed Securities [Member]
Assets:
Fixed-maturity securities	417		608
Fixed Maturities [Member] | Foreign government securities [Member]
Assets:
Fixed-maturity securities	302		313
Fixed Maturities [Member] | Recurring [Member]
Assets:
Fixed-maturity securities	10,491		9,711
Fixed Maturities [Member] | Recurring [Member] | Obligations of state and political subdivisions [Member]
Assets:
Fixed-maturity securities	5,795		5,079
Fixed Maturities [Member] | Recurring [Member] | US Treasury and Government [Member]
Assets:
Fixed-maturity securities	665		700
Fixed Maturities [Member] | Recurring [Member] | Corporate securities [Member]
Assets:
Fixed-maturity securities	1,368		1,340
Fixed Maturities [Member] | Recurring [Member] | RMBS [Member]
Assets:
Fixed-maturity securities	1,285		1,122
Fixed Maturities [Member] | Recurring [Member] | CMBS [Member]
Assets:
Fixed-maturity securities	659		549
Fixed Maturities [Member] | Recurring [Member] | Asset-backed Securities [Member]
Assets:
Fixed-maturity securities	417		608
Fixed Maturities [Member] | Recurring [Member] | Foreign government securities [Member]
Assets:
Fixed-maturity securities	302		313
Fixed Maturities [Member] | Recurring [Member] | Level 1 [Member]
Assets:
Fixed-maturity securities	0		0
Fixed Maturities [Member] | Recurring [Member] | Level 1 [Member] | Obligations of state and political subdivisions [Member]
Assets:
Fixed-maturity securities	0		0
Fixed Maturities [Member] | Recurring [Member] | Level 1 [Member] | US Treasury and Government [Member]
Assets:
Fixed-maturity securities	0		0
Fixed Maturities [Member] | Recurring [Member] | Level 1 [Member] | Corporate securities [Member]
Assets:
Fixed-maturity securities	0		0
Fixed Maturities [Member] | Recurring [Member] | Level 1 [Member] | RMBS [Member]
Assets:
Fixed-maturity securities	0		0
Fixed Maturities [Member] | Recurring [Member] | Level 1 [Member] | CMBS [Member]
Assets:
Fixed-maturity securities	0		0
Fixed Maturities [Member] | Recurring [Member] | Level 1 [Member] | Asset-backed Securities [Member]
Assets:
Fixed-maturity securities	0		0
Fixed Maturities [Member] | Recurring [Member] | Level 1 [Member] | Foreign government securities [Member]
Assets:
Fixed-maturity securities	0		0
Fixed Maturities [Member] | Recurring [Member] | Level 2 [Member]
Assets:
Fixed-maturity securities	9,721		8,981
Fixed Maturities [Member] | Recurring [Member] | Level 2 [Member] | Obligations of state and political subdivisions [Member]
Assets:
Fixed-maturity securities	5,757		5,043
Fixed Maturities [Member] | Recurring [Member] | Level 2 [Member] | US Treasury and Government [Member]
Assets:
Fixed-maturity securities	665		700
Fixed Maturities [Member] | Recurring [Member] | Level 2 [Member] | Corporate securities [Member]
Assets:
Fixed-maturity securities	1,289		1,204
Fixed Maturities [Member] | Recurring [Member] | Level 2 [Member] | RMBS [Member]
Assets:
Fixed-maturity securities	860		832
Fixed Maturities [Member] | Recurring [Member] | Level 2 [Member] | CMBS [Member]
Assets:
Fixed-maturity securities	659		549
Fixed Maturities [Member] | Recurring [Member] | Level 2 [Member] | Asset-backed Securities [Member]
Assets:
Fixed-maturity securities	189		340
Fixed Maturities [Member] | Recurring [Member] | Level 2 [Member] | Foreign government securities [Member]
Assets:
Fixed-maturity securities	302		313
Fixed Maturities [Member] | Recurring [Member] | Level 3 [Member]
Assets:
Fixed-maturity securities	770		730
Fixed Maturities [Member] | Recurring [Member] | Level 3 [Member] | Obligations of state and political subdivisions [Member]
Assets:
Fixed-maturity securities	38		36
Fixed Maturities [Member] | Recurring [Member] | Level 3 [Member] | US Treasury and Government [Member]
Assets:
Fixed-maturity securities	0		0
Fixed Maturities [Member] | Recurring [Member] | Level 3 [Member] | Corporate securities [Member]
Assets:
Fixed-maturity securities	79		136
Fixed Maturities [Member] | Recurring [Member] | Level 3 [Member] | RMBS [Member]
Assets:
Fixed-maturity securities	425		290
Fixed Maturities [Member] | Recurring [Member] | Level 3 [Member] | CMBS [Member]
Assets:
Fixed-maturity securities	0		0
Fixed Maturities [Member] | Recurring [Member] | Level 3 [Member] | Asset-backed Securities [Member]
Assets:
Fixed-maturity securities	228		268
Fixed Maturities [Member] | Recurring [Member] | Level 3 [Member] | Foreign government securities [Member]
Assets:
Fixed-maturity securities	0		0
Short-term Investments [Member]
Assets:
Fixed-maturity securities	767		904
Short-term Investments [Member] | Recurring [Member]
Assets:
Fixed-maturity securities	767		904
Short-term Investments [Member] | Recurring [Member] | Level 1 [Member]
Assets:
Fixed-maturity securities	359		506
Short-term Investments [Member] | Recurring [Member] | Level 2 [Member]
Assets:
Fixed-maturity securities	408		398
Short-term Investments [Member] | Recurring [Member] | Level 3 [Member]
Assets:
Fixed-maturity securities	$0		$0
[1]	Excludes $846 million and $525 million as of December 31, 2014 and 2013, respectively, of pre-refunded bonds, at fair value. The credit ratings are based on the underlying ratings and do not include any benefit from bond insurance.
[2]	Includes Level 3 mortgage loans that are recorded at fair value on a non-recurring basis.
[3]	Exclude restricted cash.
[4]	Government-agency obligations were approximately 44% of mortgage backed securities as of December 31, 2014 and 50% as of December 31, 2013 based on fair value.

Fair_Value_Level_3_Rollforward

- Fair Value Level 3 Rollforward Recurring Basis (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
FG VIEs' liabilities with recourse, at fair value [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value at beginning of period	($1,790)		($2,090)
Net income (loss)	94	[1],[2]	-166	[1],[2]
Other comprehensive income (loss)	0	[1]	0	[1]
Purchases	0		0
Settlements	374		343
FG VIE consolidations	-189		-12
FG VIE deconsolidations	234		135
Fair value at end of period	-1,277		-1,790
Change in unrealized gains/(losses) related to financial instruments held	-22		-169
FG VIEs' liabilities without recourse, at fair value [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value at beginning of period	-1,081		-1,051
Net income (loss)	-43	[1],[2]	-225	[1],[2]
Other comprehensive income (loss)	0	[1]	0	[1]
Purchases	0		0
Settlements	22		168
FG VIE consolidations	-42		-37
FG VIE deconsolidations	1,002		64
Fair value at end of period	-142		-1,081
Change in unrealized gains/(losses) related to financial instruments held	3		-326
Credit Risk Contract [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value at beginning of period	-1,693	[3]	-1,793	[3]
Net income (loss)	823	[1],[3],[4]	65	[1],[3],[4]
Other comprehensive income (loss)	0	[1],[3]	0	[1],[3]
Purchases	0	[3]	0	[3]
Settlements	-25	[3]	35	[3]
FG VIE consolidations	0	[3]	0	[3]
FG VIE deconsolidations	0	[3]	0	[3]
Fair value at end of period	-895	[3]	-1,693	[3]
Change in unrealized gains/(losses) related to financial instruments held	254	[3]	-139	[3]
Obligations of state and political subdivisions [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period	36		35
Net Income (loss)	4	[1],[5]	-8	[1],[5]
Other comprehensive income (loss)	-1	[1]	13	[1]
Purchases	0		0
Settlements	-1		-4
FG VIE Consolidations	0		0
FG VIE deconsolidations	0		0
Fair value at end of period	38		36
Change in unrealized gains/(losses) related to financial instruments held	-1		14
Corporate securities [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period	136		0
Net Income (loss)	-46	[1],[5]	4	[1],[5]
Other comprehensive income (loss)	-6	[1]	5	[1]
Purchases	0		130	[6]
Settlements	-5		-3
FG VIE Consolidations	0		0
FG VIE deconsolidations	0		0
Fair value at end of period	79		136
Change in unrealized gains/(losses) related to financial instruments held	-6		5
RMBS [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period	290		219
Net Income (loss)	21	[1],[5]	13	[1],[5]
Other comprehensive income (loss)	24	[1]	26	[1]
Purchases	263		86
Settlements	-59		-54
FG VIE Consolidations	-127		0
FG VIE deconsolidations	13		0
Fair value at end of period	425		290
Change in unrealized gains/(losses) related to financial instruments held	21		27
Asset-backed Securities [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period	268		306
Net Income (loss)	17	[1],[5]	67	[1],[5]
Other comprehensive income (loss)	5	[1]	-43	[1]
Purchases	0		80
Settlements	-62		-142
FG VIE Consolidations	0		0
FG VIE deconsolidations	0		0
Fair value at end of period	228		268
Change in unrealized gains/(losses) related to financial instruments held	4		-20
Other invested assets [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period	2		1
Net Income (loss)	0	[1]	-1	[1],[7]
Other comprehensive income (loss)	6	[1]	2	[1]
Purchases	70		2	[6]
Settlements	0		-2
FG VIE Consolidations	0		0
FG VIE deconsolidations	0		0
Fair value at end of period	78		2
Change in unrealized gains/(losses) related to financial instruments held	6		2
FG VIEs' assets, at fair value [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period	2,565		2,688
Net Income (loss)	164	[1],[2]	686	[1],[2]
Other comprehensive income (loss)	0	[1]	0	[1]
Purchases	0		0
Settlements	-408		-663
FG VIE Consolidations	206		48
FG VIE deconsolidations	-1,129		-194
Fair value at end of period	1,398		2,565
Change in unrealized gains/(losses) related to financial instruments held	141		623
Other assets [Member]
Fair Value Level 3 Rollforward
Fair value at beginning of period	46		36
Net Income (loss)	-11	[1],[8]	10	[1],[8]
Other comprehensive income (loss)	0	[1]	0	[1]
Purchases	0		0
Settlements	0		0
FG VIE Consolidations	0		0
FG VIE deconsolidations	0		0
Fair value at end of period	35		46
Change in unrealized gains/(losses) related to financial instruments held	($11)		$10
[1]	Realized and unrealized gains (losses) from changes in values of Level 3 financial instruments represent gains (losses) from changes in values of those financial instruments only for the periods in which the instruments were classified as Level 3.
[2]	Included in fair value gains (losses) on FG VIEs.
[3]	Represents net position of credit derivatives. The consolidated balance sheet presents gross assets and liabilities based on net counterparty exposure.
[4]	Reported in net change in fair value of credit derivatives.
[5]	Included in net realized investment gains (losses) and net investment income.
[6]	Non-cash transaction.
[7]	Reported in other income.
[8]	Recorded in fair value gains (losses) on CCS.

Quantitative_Information_Asset

- Quantitative Information - Assets (Details) (Income Approach Valuation Technique [Member], Level 3 [Member], USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Obligations of state and political subdivisions [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	38	[1]	36	[1]
Obligations of state and political subdivisions [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Rate of inflation (as a percent)	1.00%		1.00%
Cash flow receipts (as a percent)	0.50%		0.50%
Discount factor (as a percent)			4.60%
Yield (as a percent)	4.60%
Collateral recovery period (in years)	1 month		1 month
Obligations of state and political subdivisions [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Rate of inflation (as a percent)	3.00%		3.00%
Cash flow receipts (as a percent)	74.30%		60.90%
Discount factor (as a percent)			9.00%
Yield (as a percent)	8.00%
Collateral recovery period (in years)	34 years		10 years
Obligations of state and political subdivisions [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Rate of inflation (as a percent)	2.00%		2.00%
Cash flow receipts (as a percent)	63.00%		51.10%
Discount factor (as a percent)			8.00%
Yield (as a percent)	7.30%
Collateral recovery period (in years)	28 years		3 years
Corporate securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	79	[1]	136	[1]
Yield (as a percent)	17.80%		8.30%
RMBS [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	425	[1]	290	[1]
RMBS [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	4.70%		2.50%
Conditional prepayment rate (as a percent)	0.30%		0.98%
Conditional default rate (as a percent)	2.70%		5.00%
Loss severity rate (as a percent)	52.60%		48.10%
RMBS [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	11.70%		9.40%
Conditional prepayment rate (as a percent)	8.10%		15.80%
Conditional default rate (as a percent)	10.60%		25.80%
Loss severity rate (as a percent)	100.00%		102.50%
RMBS [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	6.40%		5.70%
Conditional prepayment rate (as a percent)	3.30%		4.10%
Conditional default rate (as a percent)	5.30%		17.90%
Loss severity rate (as a percent)	75.20%		87.20%
Investor-owned utilities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	95	[1]	141	[1]
Cash flow receipts (as a percent)			100.00%
Discount factor (as a percent)	7.00%		15.30%
Collateral recovery period (in years)	4 years
Investor-owned utilities [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Collateral recovery period (in years)			12 months
Liquidation value			195
Years to liquidation			0 years
Investor-owned utilities [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Collateral recovery period (in years)			6 years
Liquidation value			245
Years to liquidation			3 years
Investor-owned utilities [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Collateral recovery period (in years)			3 years 6 months
Liquidation value			228
Years to liquidation			2 years
XXX life insurance transactions [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	133	[1]	127	[1]
Yield (as a percent)	7.30%		12.50%
Other invested assets [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	83	[1]	8	[1]
Liquidity discount (as a percent)	20.00%
Recovery on delinquent loans (as a percent)	40.00%
Other invested assets [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Conditional prepayment rate (as a percent)	5.00%		6.00%
Conditional default rate (as a percent)	0.00%		1.00%
Loss severity rate (as a percent)	40.00%		40.00%
Liquidity discount (as a percent)			10.00%
Recovery on delinquent loans (as a percent)			20.00%
Net asset value (per share)	965
Other invested assets [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Conditional prepayment rate (as a percent)	15.00%		15.00%
Conditional default rate (as a percent)	7.00%		10.00%
Loss severity rate (as a percent)	75.00%		90.00%
Liquidity discount (as a percent)			20.00%
Recovery on delinquent loans (as a percent)			60.00%
Net asset value (per share)	1,159
Other invested assets [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Conditional prepayment rate (as a percent)	12.30%		13.10%
Conditional default rate (as a percent)	5.80%		3.20%
Loss severity rate (as a percent)	68.30%		73.50%
Liquidity discount (as a percent)			20.00%
Recovery on delinquent loans (as a percent)			40.00%
Net asset value (per share)	1,082
Financial Guaranty Variable Interest Entities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	1,398	[1]	2,565	[1]
Financial Guaranty Variable Interest Entities [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	2.70%		3.50%
Conditional prepayment rate (as a percent)	0.30%		0.30%
Conditional default rate (as a percent)	1.60%		3.00%
Loss severity rate (as a percent)	40.00%		37.50%
Financial Guaranty Variable Interest Entities [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	17.70%		10.20%
Conditional prepayment rate (as a percent)	11.00%		11.80%
Conditional default rate (as a percent)	11.80%		25.80%
Loss severity rate (as a percent)	100.00%		102.00%
Financial Guaranty Variable Interest Entities [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	7.90%		5.40%
Conditional prepayment rate (as a percent)	3.30%		3.60%
Conditional default rate (as a percent)	5.10%		13.60%
Loss severity rate (as a percent)	82.20%		94.60%
Other Assets [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	35	[1]	46	[1]
Fair Value Inputs Term	5 years		5 years
Other Assets [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quotes from third party pricing (in dollars per share)	52		47
Other Assets [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quotes from third party pricing (in dollars per share)	61		53
Other Assets [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quotes from third party pricing (in dollars per share)	57		50
[1]	(1)Discounted cash flow is used as valuation technique for all financial instruments.

Quantitative_Information_Liabi

- Quantitative Information - Liabilities (Details) (Income Approach Valuation Technique [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Credit derivative liabilities, net [Member] | Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Total liabilities carried at fair value	-895	[1]	-1,693	[1]
Credit derivative liabilities, net [Member] | Minimum [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Internal floor (as a percent)	0.07%		0.07%
Bank profit (as a percent)	0.01%		0.01%
Hedge cost (as a percent)	0.20%		0.46%
Credit derivative liabilities, net [Member] | Minimum [Member] | Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Year 1 loss estimates (as a percent)	0.00%		0.00%
Credit derivative liabilities, net [Member] | Maximum [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Internal floor (as a percent)	1.00%		1.00%
Bank profit (as a percent)	9.94%		14.19%
Hedge cost (as a percent)	2.44%		5.25%
Credit derivative liabilities, net [Member] | Maximum [Member] | Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Year 1 loss estimates (as a percent)	93.00%		48.00%
Credit derivative liabilities, net [Member] | Weighted Average [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Internal floor (as a percent)	0.16%		0.16%
Bank profit (as a percent)	1.27%		2.50%
Hedge cost (as a percent)	0.62%		1.10%
Credit derivative liabilities, net [Member] | Weighted Average [Member] | Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Year 1 loss estimates (as a percent)	2.10%		1.90%
Financial Guaranty Variable Interest Entities [Member] | Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Total liabilities carried at fair value	-1,419	[1]	-2,871	[1]
Financial Guaranty Variable Interest Entities [Member] | Minimum [Member] | Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Loss severity rate (as a percent)	40.00%		37.50%
Conditional default rate (as a percent)	1.60%		3.00%
Conditional prepayment rate (as a percent)	0.30%		0.30%
Yield (as a percent)	2.70%		3.50%
Financial Guaranty Variable Interest Entities [Member] | Maximum [Member] | Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Loss severity rate (as a percent)	100.00%		102.00%
Conditional default rate (as a percent)	11.80%		25.80%
Conditional prepayment rate (as a percent)	11.00%		11.80%
Yield (as a percent)	17.70%		10.20%
Financial Guaranty Variable Interest Entities [Member] | Weighted Average [Member] | Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Loss severity rate (as a percent)	82.20%		94.60%
Conditional default rate (as a percent)	5.10%		13.60%
Conditional prepayment rate (as a percent)	3.30%		3.60%
Yield (as a percent)	5.80%		5.40%
[1]	(1)Discounted cash flow is used as valuation technique for all financial instruments.

Fair_Value_Measurement_Fair_Va

Fair Value Measurement - Fair Value of Financial Instruments (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Assets:
Fixed-maturity securities	$11,258		$10,615
Short-term investments	767		904
Other invested assets	126		170
Credit derivative assets	68		94
Liabilities:
Credit derivative liabilities	963		1,787
Carrying Amount [Member]
Assets:
Fixed-maturity securities	10,491		9,711
Short-term investments	767		904
Other invested assets	108		147
Credit derivative assets	68		94
FG VIEs’ assets, at fair value	1,398		2,565
Other assets	184		179
Liabilities:
Financial guaranty insurance contracts	3,823	[1]	3,783	[1]
Long-term debt	1,303		816
Credit derivative liabilities	963		1,787
FG VIEs’ liabilities with recourse, at fair value	1,277		1,790
FG VIEs’ liabilities without recourse, at fair value	142		1,081
Other liabilities	27		36
Estimated Fair Value [Member]
Assets:
Fixed-maturity securities	10,491		9,711
Short-term investments	767		904
Other invested assets	110		155
Credit derivative assets	68		94
FG VIEs’ assets, at fair value	1,398		2,565
Other assets	184		179
Liabilities:
Financial guaranty insurance contracts	6,205	[1]	5,128	[1]
Long-term debt	1,603		970
Credit derivative liabilities	963		1,787
FG VIEs’ liabilities with recourse, at fair value	1,277		1,790
FG VIEs’ liabilities without recourse, at fair value	142		1,081
Other liabilities	$27		$36
[1]	Carrying amount includes the assets and liabilities related to financial guaranty insurance contract premiums, losses, and salvage and subrogation and other recoverables net of reinsurance.

Financial_Guaranty_Contracts_A2

Financial Guaranty Contracts Accounted for as Credit Derivatives - Credit Derivatives Subordination and Ratings (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	$34,996		$54,482
Pooled corporate obligations [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	23,621		37,321
Original Subordination (as a percent)	30.10%	[1]	31.50%	[1]
Current Subordination (as a percent)	30.70%	[1]	30.60%	[1]
Pooled corporate obligations [Member] | Collateralized loan obligations and collateral bond obligations [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	11,688		19,323
Original Subordination (as a percent)	32.00%	[1]	32.40%	[1]
Current Subordination (as a percent)	36.90%	[1]	34.00%	[1]
Pooled corporate obligations [Member] | Synthetic investment grade pooled corporate [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	7,640		9,754
Original Subordination (as a percent)	22.60%	[1]	21.60%	[1]
Current Subordination (as a percent)	20.60%	[1]	20.00%	[1]
Pooled corporate obligations [Member] | Synthetic high yield pooled corporate [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	0		2,690
Original Subordination (as a percent)	0.00%	[1]	47.20%	[1]
Current Subordination (as a percent)	0.00%	[1]	41.10%	[1]
Pooled corporate obligations [Member] | TruPS CDOs [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	3,119		3,554
Original Subordination (as a percent)	45.30%	[1]	45.50%	[1]
Current Subordination (as a percent)	35.80%	[1]	32.90%	[1]
Pooled corporate obligations [Member] | Market Value of CDOs of corporate obligations [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	1,174		2,000
Original Subordination (as a percent)	19.10%	[1]	24.40%	[1]
Current Subordination (as a percent)	20.70%	[1]	30.50%	[1]
RMBS [Member] | United States [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	2,986		5,826
Original Subordination (as a percent)	24.80%	[1]	24.40%	[1]
Current Subordination (as a percent)	33.90%	[1]	30.10%	[1]
RMBS [Member] | Option Adjustable Rate Mortgage and Alt-A Mortgage [Member] | United States [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	1,378		2,609
Original Subordination (as a percent)	16.30%	[1]	19.20%	[1]
Current Subordination (as a percent)	10.70%	[1]	8.60%	[1]
RMBS [Member] | Subprime [Member] | United States [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	1,366		2,930
Original Subordination (as a percent)	31.10%	[1]	30.50%	[1]
Current Subordination (as a percent)	50.50%	[1]	51.90%	[1]
RMBS [Member] | Prime [Member] | United States [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	223		264
Original Subordination (as a percent)	10.90%	[1]	10.90%	[1]
Current Subordination (as a percent)	0.00%	[1]	3.20%	[1]
RMBS [Member] | Closed-end [Member] | United States [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	19		23
Original Subordination (as a percent)	0.00%	[1]	0.00%	[1]
Current Subordination (as a percent)	0.00%	[1]	0.00%	[1]
CMBS [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	1,952		3,744
Original Subordination (as a percent)	35.30%	[1]	33.50%	[1]
Current Subordination (as a percent)	43.60%	[1]	42.50%	[1]
Other [Member]
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	$6,437		$7,591
Original Subordination (as a percent)	0.00%	[1]	0.00%	[1]
Current Subordination (as a percent)	0.00%	[1]	0.00%	[1]
[1]	Represents the sum of subordinate tranches and over-collateralization and does not include any benefit from excess interest collections that may be used to absorb losses.

Financial_Guaranty_Contracts_A3

Financial Guaranty Contracts Accounted for as Credit Derivatives - Distribution of Credit Derivative Net Par Outstanding by Internal Rating (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Credit Derivatives
Net Par Outstanding	34,996	54,482
Internal Credit Rating, AAA [Member]
Credit Derivatives
Net Par Outstanding	21,817	38,244
Internal Credit Rating, AA [Member]
Credit Derivatives
Net Par Outstanding	5,398	3,648
Internal Credit Rating, A [Member]
Credit Derivatives
Net Par Outstanding	1,982	3,636
Internal Credit Rating, BBB [Member]
Credit Derivatives
Net Par Outstanding	2,774	4,161
BIG [Member]
Credit Derivatives
Net Par Outstanding	3,025	4,793
Credit Concentration Risk [Member] | Derivative, Aggregate Notional Amount [Member]
Credit Derivatives
Percentage of installment premiums denominated in currencies other than the U.S. dollar	100.00%	100.00%
Credit Concentration Risk [Member] | Derivative, Aggregate Notional Amount [Member] | Internal Credit Rating, AAA [Member]
Credit Derivatives
Percentage of installment premiums denominated in currencies other than the U.S. dollar	62.30%	70.20%
Credit Concentration Risk [Member] | Derivative, Aggregate Notional Amount [Member] | Internal Credit Rating, AA [Member]
Credit Derivatives
Percentage of installment premiums denominated in currencies other than the U.S. dollar	15.40%	6.70%
Credit Concentration Risk [Member] | Derivative, Aggregate Notional Amount [Member] | Internal Credit Rating, A [Member]
Credit Derivatives
Percentage of installment premiums denominated in currencies other than the U.S. dollar	5.70%	6.70%
Credit Concentration Risk [Member] | Derivative, Aggregate Notional Amount [Member] | Internal Credit Rating, BBB [Member]
Credit Derivatives
Percentage of installment premiums denominated in currencies other than the U.S. dollar	8.00%	7.60%
Credit Concentration Risk [Member] | Derivative, Aggregate Notional Amount [Member] | BIG [Member]
Credit Derivatives
Percentage of installment premiums denominated in currencies other than the U.S. dollar	8.60%	8.80%

Financial_Guaranty_Contracts_A4

Financial Guaranty Contracts Accounted for as Credit Derivatives - Net Change in Fair Value of Credit Derivatives Gains (Losses) (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Credit Derivatives
Realized gains on credit derivatives									$73		$121		$128
Net credit derivative losses (paid and payable) recovered and recoverable and other settlements									-50		-163		-236
Realized gains (losses) and other settlements on credit derivatives									23		-42		-108
Net change in unrealized gains (losses) on credit derivatives									800	[1]	107	[1]	-477	[1]
Net change in fair value of credit derivatives	676	255	103	-211	229	354	74	-592	823		65		-585
Pooled corporate obligations [Member]
Credit Derivatives
Net change in unrealized gains (losses) on credit derivatives									-18		-32		59
CMBS [Member]
Credit Derivatives
Net change in unrealized gains (losses) on credit derivatives									2		0		2
Other [Member]
Credit Derivatives
Net change in unrealized gains (losses) on credit derivatives									2	[2]	208	[2]	13	[2]
United States [Member] | RMBS [Member]
Credit Derivatives
Net change in unrealized gains (losses) on credit derivatives									814		-69		-551
Credit Risk Contract [Member]
Credit Derivatives
Net par of terminated CDS contracts									3,591		4,054		2,264
Realized gains (losses) and other settlements									$1		$21		$3
[1]	Except for net estimated credit impairments (i.e., net expected loss to be paid as discussed in Note 6), the unrealized gains and losses on credit derivatives are expected to reduce to zero as the exposure approaches its maturity date. With considerable volatility continuing in the market, unrealized gains (losses) on credit derivatives may fluctuate significantly in future periods.
[2]	“Other” includes all other U.S. and international asset classes, such as commercial receivables, international infrastructure, international RMBS securities, and pooled infrastructure securities.

Financial_Guaranty_Contracts_A5

Financial Guaranty Contracts Accounted for as Credit Derivatives - CDS Spread and Components of Credit Derivative Assets (Liabilities) (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Credit Derivatives
Fair value of credit derivatives before effect of AGC and AGM credit spreads	-2,029		-3,442
Plus: Effect of AGC and AGM credit spreads	1,134		1,749
Net fair value of credit derivatives	-895	[1]	-1,693
Credit Risk Contract, 5 Year Spread [Member] | AGC [Member]
Credit Derivatives
Quoted price of CDS contract (as a percent)	3.23%		4.60%	6.78%
Credit Risk Contract, 5 Year Spread [Member] | AGM [Member]
Credit Derivatives
Quoted price of CDS contract (as a percent)	3.25%		5.25%	5.36%
Credit Risk Contract, 1 Year Spread [Member] | AGC [Member]
Credit Derivatives
Quoted price of CDS contract (as a percent)	0.80%		1.85%	2.70%
Credit Risk Contract, 1 Year Spread [Member] | AGM [Member]
Credit Derivatives
Quoted price of CDS contract (as a percent)	0.85%		2.20%	2.57%
[1]	Includes the effects of spreads on both the underlying asset classes and the Company’s own credit spread.

Financial_Guaranty_Contracts_A6

Financial Guaranty Contracts Accounted for as Credit Derivatives - Net Fair Value and Expected Losses of Credit Derivatives by Sector (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Credit Derivatives
Net fair value of credit derivatives	($895)	[1]	($1,693)
Expected Loss to be (Paid) Recovered	-58	[2]	-184	[2]
Pooled corporate obligations [Member]
Credit Derivatives
Net fair value of credit derivatives	-49		-30
Expected Loss to be (Paid) Recovered	-23	[2]	-48	[2]
RMBS [Member] | United States [Member]
Credit Derivatives
Net fair value of credit derivatives	-494		-1,308
Expected Loss to be (Paid) Recovered	-73	[2]	-175	[2]
CMBS [Member]
Credit Derivatives
Net fair value of credit derivatives	0		-2
Expected Loss to be (Paid) Recovered	0	[2]	0	[2]
Other [Member]
Credit Derivatives
Net fair value of credit derivatives	-352		-353
Expected Loss to be (Paid) Recovered	38	[2]	39	[2]
Credit Risk Contract [Member]
Credit Derivatives
R&W Included in Credit Derivative Asset (Liability)	$86		$180
[1]	Includes the effects of spreads on both the underlying asset classes and the Company’s own credit spread.
[2]	Includes R&W benefit of $86 million as of December 31, 2014 and $180 million as of December 31, 2013.

Financial_Guaranty_Contracts_A7

Financial Guaranty Contracts Accounted for as Credit Derivatives - Effect of Changes in Credit Spread (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Credit Risk Derivatives, 100 Percent Widening in Spreads, Effect on Fair Value	($1,821)	[1]
Credit Risk Derivatives, 50 Percent Widening in Spreads, Effect on Fair Value	-1,358	[1]
Credit Risk Derivatives, 25 Percent Widening in Spreads, Effect on Fair Value	-1,128	[1]
Credit Risk Derivatives, 10 Percent Widening in Spreads, Effect on Fair Value	-989	[1]
Net fair value of credit derivatives	-895	[1]	-1,693
Credit Risk Derivatives, 10 Percent Narrowing in Spreads, Effect on Fair Value	-809	[1]
Credit Risk Derivatives, 25 Percent Narrowing in Spreads, Effect on Fair Value	-679	[1]
Credit Risk Derivatives, 50 Percent Narrowing in Spreads, Effect on Fair Value	-466	[1]
Credit Risk Derivatives, 100 Percent Widening in Spreads, Effect on Unrealized Gain (Loss)	-926	[1]
Credit Risk Derivatives, 50 Percent Widening in Spreads, Effect on Unrealized Gain (Loss)	-463	[1]
Credit Risk Derivatives, 25 Percent Widening in Spreads, Effect on Unrealized Gain (Loss)	-233	[1]
Credit Risk Derivatives, 10 Percent Widening in Spreads, Effect on Unrealized Gain (Loss)	-94	[1]
Credit Risk Derivatives, Base Scenario, Effect on Unrealized Gain (Loss)	0	[1]
Credit Risk Derivatives, 10 Percent Narrowing in Spreads, Effect on Unrealized Gain (Loss)	86	[1]
Credit Risk Derivatives, 25 Percent Narrowing in Spreads, Effect on Unrealized Gain (Loss)	216	[1]
Credit Risk Derivatives, 50 Percent Narrowing in Spreads, Effect on Unrealized Gain (Loss)	$429	[1]
[1]	Includes the effects of spreads on both the underlying asset classes and the Company’s own credit spread.

Financial_Guaranty_Contracts_A8

Financial Guaranty Contracts Accounted for as Credit Derivatives - Narrative (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Sep. 12, 2014	Oct. 10, 2013
															Transaction	Transaction
Credit Derivatives
Estimated remaining weighted average life of credit derivatives (in years)									4 years 7 months 30 days		4 years 1 month 15 days
Net par outstanding	$34,996				$54,482				$34,996		$54,482
Net unrealized gains (losses)									800	[1]	107	[1]	-477	[1]
Net change in fair value of credit derivatives	676	255	103	-211	229	354	74	-592	823		65		-585
Gain from narrowing of spreads	346								1,413
Collateral agreed to be posted	376				677				376		677
Market value collateralized debt obligations of corporate obligations [Member]
Credit Derivatives
Maximum average obligor size (as a percent)	1.00%								1.00%
Maximum exposure of one industry (as a percent)	10.00%								10.00%
Net par outstanding	23,621				37,321				23,621		37,321
Net unrealized gains (losses)									-18		-32		59
Other pooled infrastructure [Member]
Credit Derivatives
Net par outstanding	2,000								2,000
Pooled infrastructure [Member]
Credit Derivatives
Number of transactions	1								1
Remaining other CDS [Member]
Credit Derivatives
Net par outstanding	4,400								4,400
Film securitization CDS [Member]
Credit Derivatives
Net unrealized gains (losses)											127
Net change in fair value of credit derivatives											7
Collateral Debt Obligations, Collateral Requirement [Member]
Credit Derivatives
Amount of par subject to collateral for which the amount of collateral is capped	6,100								6,100
Collateral Debt Obligations, Collateral Cap Negotiated [Member]
Credit Derivatives
Amount of par subject to collateral for which the amount of collateral is capped	5,900								5,900
Collateral Debt Obligations, No Cap Negotiated [Member]
Credit Derivatives
Amount of par subject to collateral for which the amount of collateral is capped	665								665
Collateral agreed to be posted	376				677				376		677
Notional amount subject to collateral based on movements in the mark-to-market valuation of the underlying exposure	242				347				242		347
Collateral posted, based on mark-to-market valuation	25				62				25		62
Credit Risk Contract [Member]
Credit Derivatives
Realized gains (losses) and other settlements									1		21		3
Credit Risk Contract [Member] | Film securitization CDS [Member]
Credit Derivatives
Realized gains (losses) and other settlements											120
Deutsche Bank [Member]
Credit Derivatives
Number of transactions terminated	1								1						2	1
Variable Interest Entity, Primary Beneficiary [Member] | Deutsche Bank [Member] | Settled Litigation [Member]
Credit Derivatives
Net unrealized gains (losses)													85
Option Adjustable Rate Mortgage and Alt-A Mortgage [Member] | First Lien [Member] | RMBS [Member]
Credit Derivatives
Unrealized fair value gain on termination of transactions									$543
Alt-A [Member] | First Lien [Member] | RMBS [Member]
Credit Derivatives
Number of transactions terminated	3								3
Option Adjustable Rate Mortgage [Member] | First Lien [Member] | RMBS [Member]
Credit Derivatives
Number of transactions terminated	1								1
[1]	Except for net estimated credit impairments (i.e., net expected loss to be paid as discussed in Note 6), the unrealized gains and losses on credit derivatives are expected to reduce to zero as the exposure approaches its maturity date. With considerable volatility continuing in the market, unrealized gains (losses) on credit derivatives may fluctuate significantly in future periods.

Consolidated_Variable_Interest2

Consolidated Variable Interest Entities - Narrative (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
									Entity
Variable Interest Entity [Line Items]
Net fair value gains and losses on FG VIEs are expected to reverse to zero at maturity of the VIE debt	$0								$0
Credit Risk Derivatives at Fair Value before Effect of Credit Spread Net 1 [Abstract]
Fair value gains (losses) on FG VIEs	23,000,000	50,000,000	25,000,000	157,000,000	93,000,000	40,000,000	143,000,000	70,000,000	255,000,000	346,000,000	191,000,000
Number of entities to be deconsolidated									7
Number of FG VIE's matured									-2
Effect on shareholders’ equity (decrease) increase	5,758,000,000				5,115,000,000				5,758,000,000	5,115,000,000	4,994,000,000	4,652,000,000
Net earned premiums	158,000,000	144,000,000	136,000,000	132,000,000	182,000,000	159,000,000	163,000,000	248,000,000	570,000,000	752,000,000	853,000,000
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Net gain on deconsolidation				120,000,000					120,000,000
Net loss on consolidation of VIEs									26,000,000
Net gain (loss) on consolidation and deconsolidation during period										7,000,000	6,000,000
Credit Risk Derivatives at Fair Value before Effect of Credit Spread Net 1 [Abstract]
Fair value gains (losses) on FG VIEs									255,000,000	346,000,000	191,000,000
Gain from Company's exercise of options				37,000,000
Number of FG VIE's matured									-2	-1	-2
Effect on shareholders’ equity (decrease) increase	-44,000,000				-172,000,000				-44,000,000	-172,000,000
Net earned premiums									-32,000,000	-60,000,000	-153,000,000
Number of VIE that did not require consolidation	32				40				32	40	33	33
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member]
Credit Risk Derivatives at Fair Value before Effect of Credit Spread Net 1 [Abstract]
Number of VIE that did not require consolidation	930				1,000				930	1,000
Residential Mortgage Backed Securities and Other Insurance Products [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Credit Risk Derivatives at Fair Value before Effect of Credit Spread Net 1 [Abstract]
Total unpaid principal balance for the VIEs' assets that were over 90 days or more past due	183,000,000				750,000,000				183,000,000	750,000,000
Difference between the aggregate unpaid principal and aggregate fair value of the VIEs' Assets	941,000,000				1,940,000,000				941,000,000	1,940,000,000
Change in the instrument specific credit risk of the VIEs' assets									116,000,000	340,000,000	413,000,000
Unpaid principal for FG VIEs’ liabilities with recourse	1,912,000,000				2,316,000,000				1,912,000,000	2,316,000,000
Unpaid principal for FG VIEs' liabilities with and without recourse	916,000,000				1,611,000,000				916,000,000	1,611,000,000
Various counterparties [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Credit Risk Derivatives at Fair Value before Effect of Credit Spread Net 1 [Abstract]
Fair value gains (losses) on FG VIEs									265,000,000
Deutsche Bank [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Credit Risk Derivatives at Fair Value before Effect of Credit Spread Net 1 [Abstract]
Fair value gains (losses) on FG VIEs											$166,000,000

Consolidated_Variable_Interest3

Consolidated Variable Interest Entities - Number of FG VIE's Consolidated (Details)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
	Entity		Entity		Entity
Number of FG VIEs Consolidated [Roll Forward]
Number of FG VIE's matured	-2
Variable Interest Entity, Primary Beneficiary [Member]
Number of FG VIEs Consolidated [Roll Forward]
Number of FG VIE's consolidated, beginning of period	40		33		33
Number of FG VIE's consolidated	2	[1]	11	[1]	2	[1]
Number of FG VIE's deconsolidated	-8	[1]	-3	[1]	0	[1]
Number of FG VIE's matured	-2		-1		-2
Number of FG VIE's consolidated, end of period	32		40		33
[1]	(1)Net gain on deconsolidation was $120 million and net loss on consolidation was $26 million in 2014. Net loss on consolidation and deconsolidation was $7 million in 2013 and $6 million in 2012, respectively, and recorded in “fair value gains (losses) on FG VIEs” in the consolidated statement of operations.

Consolidated_Variable_Interest4

Consolidated Variable Interest Entities - Consolidated FG VIE's By Type of Collateral (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	$1,239	$1,449
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	1,277	1,790
Financial guaranty variable interest entities' assets without recourse, at fair value	163	1,116
Financial guaranty variable interest entities’ liabilities without recourse, at fair value	142	1,081
Financial guaranty variable interest entities’ assets, at fair value	1,402	2,565
Financial guaranty variable interest entities’ liabilities, at fair value	1,419	2,871
Other Insurance Product Line [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	369	359
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	369	359
United States [Member] | First Lien [Member] | RMBS [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	632	630
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	581	791
United States [Member] | Second Lien [Member] | RMBS [Member]
Variable Interest Entity [Line Items]
Financial guaranty variable interest entities' assets with recourse, at fair value	238	460
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	$327	$640

Consolidated_Variable_Interest5

Consolidated Variable Interest Entities - Effect of Consolidating FG VIE's on Financial Information (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Variable Interest Entity [Line Items]
Net earned premiums	$158	$144	$136	$132	$182	$159	$163	$248	$570	$752	$853
Net investment income	102	102	96	103	107	99	93	94	403	393	404
Net realized investment gains (losses)	-35	-19	-8	2	29	-7	2	28	-60	52	1
Fair value gains (losses) on FG VIEs	23	50	25	157	93	40	143	70	255	346	191
Other income (loss)	-3	-11	7	21	-5	16	-7	-14	14	-10	108
Loss and LAE	72	-44	57	41	85	55	62	-48	126	154	504
Income (loss) before income taxes	756	488	218	69	489	536	329	-212	1,531	1,142	132
Provision (benefit) for income taxes	224	133	59	27	140	152	110	-68	443	334	22
Net income (loss)	532	355	159	42	349	384	219	-144	1,088	808	110
Net cash flows provided by (used in) operating activities									577	244	-165
Effect on shareholders’ equity (decrease) increase	5,758				5,115				5,758	5,115	4,994	4,652
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Net earned premiums									-32	-60	-153
Net investment income									-11	-13	-13
Net realized investment gains (losses)									-5	2	4
Fair value gains (losses) on FG VIEs									255	346	191
Other income (loss)									-2	0	0
Loss and LAE									30	21	65
Income (loss) before income taxes									235	296	94
Provision (benefit) for income taxes									82	103	32
Net income (loss)									153	193	62
Net cash flows provided by (used in) operating activities									68	-136	166
Effect on shareholders’ equity (decrease) increase	($44)				($172)				($44)	($172)

Investments_and_Cash_Net_Inves

Investments and Cash - Net Investment Income (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net Investment Income
Gross investment income									$412	$401	$413
Investment expenses									-9	-8	-9
Net investment income	102	102	96	103	107	99	93	94	403	393	404
Fixed Maturities, Managed Externally [Member]
Net Investment Income
Gross investment income									324	322	346
Fixed Maturities, Managed Internally [Member]
Net Investment Income
Gross investment income									74	74	60
Other Invested Assets, Internally Managed [Member]
Net Investment Income
Gross investment income									13	5	6
Other Investments [Member]
Net Investment Income
Gross investment income									$1	$0	$1

Investments_and_Cash_Net_Reali

Investments and Cash - Net Realized Investment Gains (Losses) (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net Realized Investment Gains (Losses)
Gross realized gains on available-for-sale securities									$14	$73	$29
Gross realized gains on other assets in investment portfolio									8	40	14
Gross realized losses on available-for-sale securities									-5	-12	-23
Gross realized losses on other assets in investment portfolio									-2	-7	-2
Net impairment loss									-75	-42	-17
Net realized investment gains (losses)	($35)	($19)	($8)	$2	$29	($7)	$2	$28	($60)	$52	$1

Investments_and_Cash_Roll_Forw

Investments and Cash - Roll Forward of Credit Losses in the Investment Portfolio (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Roll Forward of Credit Losses in the Investment Portfolio
Credit losses, beginning of period	$80	$64	$47
Additions for credit losses on securities for which an other-than-temporary-impairment was not previously recognized	64	18	14
Eliminations of securities issued by FG VIEs	-15	0	0
Reductions for securities sold during the period	-12	-21	0
Additions for credit losses on securities for which an other-than-temporary-impairment was previously recognized	7	19	3
Credit losses, end of period	$124	$80	$64

Investments_and_Cash_Fixed_Mat

Investments and Cash - Fixed Maturity Securities and Short Term Investments (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Investments
Percent of Total	100.00%	[1]	100.00%	[1]
Amortized Cost	$10,739		$10,392
Gross Unrealized Gains	552		370
Gross Unrealized Losses	-33		-147
Fixed-maturity securities	11,258		10,615
AOCI(2) Gain (Loss) on Securities with Other-Than-Temporary Impairment	8	[2]	-37	[2]
Fixed Maturities [Member]
Investments
Percent of Total	93.00%	[1]	91.00%	[1]
Amortized Cost	9,972		9,488
Gross Unrealized Gains	552		370
Gross Unrealized Losses	-33		-147
Fixed-maturity securities	10,491		9,711
AOCI(2) Gain (Loss) on Securities with Other-Than-Temporary Impairment	8	[2]	-37	[2]
Short-term Investments [Member]
Investments
Percent of Total	7.00%	[1]	9.00%	[1]
Amortized Cost	767		904
Gross Unrealized Gains	0		0
Gross Unrealized Losses	0		0
Fixed-maturity securities	767		904
AOCI(2) Gain (Loss) on Securities with Other-Than-Temporary Impairment	0	[2]	0	[2]
Obligations of state and political subdivisions [Member]
Investments
Amortized Cost	4,619	[3]	4,411	[3]
Fixed-maturity securities	4,949	[3]	4,554	[3]
Obligations of state and political subdivisions [Member] | Fixed Maturities [Member]
Investments
Percent of Total	50.00%	[1]	47.00%	[1]
Amortized Cost	5,416		4,899
Gross Unrealized Gains	380		219
Gross Unrealized Losses	-1		-39
Fixed-maturity securities	5,795		5,079
AOCI(2) Gain (Loss) on Securities with Other-Than-Temporary Impairment	7	[2]	4	[2]
US Treasury and Government [Member] | Fixed Maturities [Member]
Investments
Percent of Total	6.00%	[1]	6.00%	[1]
Amortized Cost	635		674
Gross Unrealized Gains	31		32
Gross Unrealized Losses	-1		-6
Fixed-maturity securities	665		700
AOCI(2) Gain (Loss) on Securities with Other-Than-Temporary Impairment	0	[2]	0	[2]
Corporate securities [Member] | Fixed Maturities [Member]
Investments
Percent of Total	12.00%	[1]	13.00%	[1]
Amortized Cost	1,320		1,314
Gross Unrealized Gains	53		44
Gross Unrealized Losses	-5		-18
Fixed-maturity securities	1,368		1,340
AOCI(2) Gain (Loss) on Securities with Other-Than-Temporary Impairment	-2	[2]	0	[2]
RMBS [Member] | Fixed Maturities [Member]
Investments
Percent of Total	12.00%	[1],[4]	11.00%	[1],[4]
Amortized Cost	1,255	[4]	1,160	[4]
Gross Unrealized Gains	51	[4]	34	[4]
Gross Unrealized Losses	-21	[4]	-72	[4]
Fixed-maturity securities	1,285	[4]	1,122	[4]
AOCI(2) Gain (Loss) on Securities with Other-Than-Temporary Impairment	0	[2],[4]	-43	[2],[4]
CMBS [Member] | Fixed Maturities [Member]
Investments
Percent of Total	6.00%	[1],[4]	5.00%	[1],[4]
Amortized Cost	639	[4]	536	[4]
Gross Unrealized Gains	20	[4]	17	[4]
Gross Unrealized Losses	0	[4]	-4	[4]
Fixed-maturity securities	659	[4]	549	[4]
AOCI(2) Gain (Loss) on Securities with Other-Than-Temporary Impairment	0	[2],[4]	0	[2],[4]
Asset-backed Securities [Member] | Fixed Maturities [Member]
Investments
Percent of Total	4.00%	[1]	6.00%	[1]
Amortized Cost	411		605
Gross Unrealized Gains	9		10
Gross Unrealized Losses	-3		-7
Fixed-maturity securities	417		608
AOCI(2) Gain (Loss) on Securities with Other-Than-Temporary Impairment	3	[2]	2	[2]
Foreign government securities [Member] | Fixed Maturities [Member]
Investments
Percent of Total	3.00%	[1]	3.00%	[1]
Amortized Cost	296		300
Gross Unrealized Gains	8		14
Gross Unrealized Losses	-2		-1
Fixed-maturity securities	302		313
AOCI(2) Gain (Loss) on Securities with Other-Than-Temporary Impairment	$0	[2]	$0	[2]
[1]	Based on amortized cost.
[2]	Accumulated OCI. See also Note 21, Other Comprehensive Income.
[3]	Excludes $846 million and $525 million as of December 31, 2014 and 2013, respectively, of pre-refunded bonds, at fair value. The credit ratings are based on the underlying ratings and do not include any benefit from bond insurance.
[4]	Government-agency obligations were approximately 44% of mortgage backed securities as of December 31, 2014 and 50% as of December 31, 2013 based on fair value.

Investments_and_Cash_Fair_Valu

Investments and Cash - Fair Value of Available-for-Sale Municipal Bond Portfolio by State and Revenue Sources (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	$11,258		$10,615
Amortized Cost	10,739		10,392
State General Obligation [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	580	[1]	510	[1]
State General Obligation [Member] | Texas [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	60	[1]	77	[1]
State General Obligation [Member] | New York [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	13	[1]	12	[1]
State General Obligation [Member] | California [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	45	[1]	32	[1]
State General Obligation [Member] | Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	47	[1]	33	[1]
State General Obligation [Member] | Illinois [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	20	[1]	14	[1]
State General Obligation [Member] | Massachusetts [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	46	[1]	44	[1]
State General Obligation [Member] | Washington [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	67	[1]	31	[1]
State General Obligation [Member] | Arizona [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	0	[1]	0	[1]
State General Obligation [Member] | Michigan [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	0	[1]	0	[1]
State General Obligation [Member] | Georgia [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities			13	[1]
State General Obligation [Member] | Ohio [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	6	[1]
State General Obligation [Member] | All others [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	276	[1]	254	[1]
Local General Obligation [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	891	[1]	888	[1]
Local General Obligation [Member] | Texas [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	293	[1]	299	[1]
Local General Obligation [Member] | New York [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	41	[1]	58	[1]
Local General Obligation [Member] | California [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	70	[1]	86	[1]
Local General Obligation [Member] | Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	34	[1]	59	[1]
Local General Obligation [Member] | Illinois [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	99	[1]	70	[1]
Local General Obligation [Member] | Massachusetts [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	8	[1]	16	[1]
Local General Obligation [Member] | Washington [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	48	[1]	19	[1]
Local General Obligation [Member] | Arizona [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	7	[1]	7	[1]
Local General Obligation [Member] | Michigan [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	0	[1]	28	[1]
Local General Obligation [Member] | Georgia [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities			18	[1]
Local General Obligation [Member] | Ohio [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	40	[1]
Local General Obligation [Member] | All others [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	251	[1]	228	[1]
Revenue Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	3,478	[1]	3,156	[1]
Amortized Cost	3,235		3,062
Revenue Bonds [Member] | Texas [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	305	[1]	277	[1]
Revenue Bonds [Member] | New York [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	551	[1]	519	[1]
Revenue Bonds [Member] | California [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	377	[1]	354	[1]
Revenue Bonds [Member] | Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	256	[1]	242	[1]
Revenue Bonds [Member] | Illinois [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	177	[1]	156	[1]
Revenue Bonds [Member] | Massachusetts [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	169	[1]	147	[1]
Revenue Bonds [Member] | Washington [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	163	[1]	153	[1]
Revenue Bonds [Member] | Arizona [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	170	[1]	166	[1]
Revenue Bonds [Member] | Michigan [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	132	[1]	102	[1]
Revenue Bonds [Member] | Georgia [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities			97	[1]
Revenue Bonds [Member] | Ohio [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	82	[1]
Revenue Bonds [Member] | All others [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	1,096	[1]	943	[1]
Transportation [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	796		642
Amortized Cost	733		615
Water and Sewer [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	563		459
Amortized Cost	527		453
Tax backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	551		708
Amortized Cost	514		686
Higher education [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	527		358
Amortized Cost	492		353
Municipal utilities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	512		500
Amortized Cost	479		482
Healthcare [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	346		289
Amortized Cost	317		281
All Others [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	183		200
Amortized Cost	173		192
Obligations of state and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	4,949	[1]	4,554	[1]
Amortized Cost	4,619	[1]	4,411	[1]
Fixed-maturity securities, available-for-sale, at fair value	846		525
Obligations of state and political subdivisions [Member] | Texas [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	658	[1]	653	[1]
Amortized Cost	613	[1]	629	[1]
Obligations of state and political subdivisions [Member] | New York [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	605	[1]	589	[1]
Amortized Cost	571	[1]	575	[1]
Obligations of state and political subdivisions [Member] | California [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	492	[1]	472	[1]
Amortized Cost	449	[1]	452	[1]
Obligations of state and political subdivisions [Member] | Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	337	[1]	334	[1]
Amortized Cost	311	[1]	318	[1]
Obligations of state and political subdivisions [Member] | Illinois [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	296	[1]	240	[1]
Amortized Cost	275	[1]	234	[1]
Obligations of state and political subdivisions [Member] | Massachusetts [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	223	[1]	207	[1]
Amortized Cost	204	[1]	200	[1]
Obligations of state and political subdivisions [Member] | Washington [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	278	[1]	203	[1]
Amortized Cost	262	[1]	199	[1]
Obligations of state and political subdivisions [Member] | Arizona [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	177	[1]	173	[1]
Amortized Cost	165	[1]	170	[1]
Obligations of state and political subdivisions [Member] | Michigan [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	132	[1]	130	[1]
Amortized Cost	122	[1]	125	[1]
Obligations of state and political subdivisions [Member] | Georgia [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities			128	[1]
Amortized Cost			128	[1]
Obligations of state and political subdivisions [Member] | Ohio [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	128	[1]
Amortized Cost	119	[1]
Obligations of state and political subdivisions [Member] | All others [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed-maturity securities	1,623	[1]	1,425	[1]
Amortized Cost	$1,528	[1]	$1,381	[1]
[1]	Excludes $846 million and $525 million as of December 31, 2014 and 2013, respectively, of pre-refunded bonds, at fair value. The credit ratings are based on the underlying ratings and do not include any benefit from bond insurance.

Investments_and_Cash_Gross_Unr

Investments and Cash - Gross Unrealized Loss by Length of Time (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified	Security		Security
Less than 12 months
Fair value	$797		$2,140
Unrealized loss	-10		-91
12 months or more
Fair Value	393		237
Unrealized loss	-23		-56
Total
Fair value	1,190		2,377
Unrealized loss	-33		-147
Number of securities
Less than 12 months (in securities)	125	[1]	425
12 months or more (in securities)	82	[1]	33
Total (in securities)	198	[1]	458
Number of securities with OTTI
Less than 12 months (in securities)	3		13
12 months or more (in securities)	7		11
Total (in securities)	10		24
Obligations of state and political subdivisions [Member]
Less than 12 months
Fair value	64		781
Unrealized loss	0		-39
12 months or more
Fair Value	25		5
Unrealized loss	-1		0
Total
Fair value	89		786
Unrealized loss	-1		-39
US Treasury and Government [Member]
Less than 12 months
Fair value	139		173
Unrealized loss	0		-6
12 months or more
Fair Value	68		0
Unrealized loss	-1		0
Total
Fair value	207		173
Unrealized loss	-1		-6
Corporate securities [Member]
Less than 12 months
Fair value	189		401
Unrealized loss	-3		-18
12 months or more
Fair Value	104		3
Unrealized loss	-2		0
Total
Fair value	293		404
Unrealized loss	-5		-18
RMBS [Member]
Less than 12 months
Fair value	205		414
Unrealized loss	-3		-21
12 months or more
Fair Value	159		186
Unrealized loss	-18		-51
Total
Fair value	364		600
Unrealized loss	-21		-72
CMBS [Member]
Less than 12 months
Fair value	36		121
Unrealized loss	0		-4
12 months or more
Fair Value	19		0
Unrealized loss	0		0
Total
Fair value	55		121
Unrealized loss	0		-4
Asset-backed Securities [Member]
Less than 12 months
Fair value	56		196
Unrealized loss	-2		-2
12 months or more
Fair Value	18		42
Unrealized loss	-1		-5
Total
Fair value	74		238
Unrealized loss	-3		-7
Foreign government securities [Member]
Less than 12 months
Fair value	108		54
Unrealized loss	-2		-1
12 months or more
Fair Value	0		1
Unrealized loss	0		0
Total
Fair value	108		55
Unrealized loss	($2)		($1)
[1]	The number of securities does not add across because of lots of the same securities that have been purchased at different times and appear in both categories above (i.e., Less than 12 months and 12 months or more). If a security appears in both categories, it is counted only once in the Total column.

Investments_and_Cash_Distribut

Investments and Cash - Distribution of Fixed-Maturity Securities by Contractual Maturity (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Amortized Cost
Amortized cost	$9,972		$9,488
Estimated Fair Value
Estimated fair value	11,258		10,615
Fixed Maturities [Member]
Amortized Cost
Due within one year	111
Due after one year through five years	1,961
Due after five years through 10 years	2,286
Due after 10 years	3,720
Amortized cost	9,972
Estimated Fair Value
Due within one year	112
Due after one year through five years	2,028
Due after five years through 10 years	2,422
Due after 10 years	3,985
Estimated fair value	10,491		9,711
Fixed Maturities [Member] | RMBS [Member]
Amortized Cost
Amortized cost	1,255
Estimated Fair Value
Estimated fair value	1,285	[1]	1,122	[1]
Fixed Maturities [Member] | CMBS [Member]
Amortized Cost
Amortized cost	639
Estimated Fair Value
Estimated fair value	$659	[1]	$549	[1]
[1]	Government-agency obligations were approximately 44% of mortgage backed securities as of December 31, 2014 and 50% as of December 31, 2013 based on fair value.

Investments_and_Cash_Internall

Investments and Cash - Internally Managed Investment Portfolio (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Schedule of Cost-method Investments [Line Items]
Fixed-maturity securities	$11,258	$10,615
Other invested assets	126	170
Internally managed portfolio	11,384	10,785
Fixed Maturities, Managed Internally [Member]
Schedule of Cost-method Investments [Line Items]
Fixed-maturity securities	835	761
Other Invested Assets, Internally Managed [Member]
Schedule of Cost-method Investments [Line Items]
Other invested assets	46	82
Other, Internally Managed [Member]
Schedule of Cost-method Investments [Line Items]
Other invested assets	79	88
Internally Managed Portfolio [Member]
Schedule of Cost-method Investments [Line Items]
Internally managed portfolio	$960	$931

Investments_and_Cash_Narrative

Investments and Cash - Narrative (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Investment [Line Items]
Government Agency Obligations as a Percentage of Total Mortgage Backed Securities	44.00%	50.00%
Percentage of decline in market value of security below amortized cost, considered for assessing impairment of investments	20.00%
Continuous period of decline in market value of security, considered for assessing impairment of investments	12 months
Accrued investment income	98	93
Number of outside managers managing investment portfolio	4
Number of securities with unrealized losses greater than 10% of book value for 12 months or more	3
Total unrealized losses for securities having losses greater than 10% of book value for 12 months or more	15
Assets held-in-trust	268	396
Fair market value of company's pledged securities	376	677
Investment in Portfolio Funding Company LLC I
Investment [Line Items]
Percentage of an equity investment acquired in a restructuring of an insured CDS	50.00%
Investments [Member] | Available-for-sale Securities [Member]
Investment [Line Items]
Percentage of installment premiums denominated in currencies other than the U.S. dollar	99.00%
Investments [Member] | Internally Managed Portfolio [Member]
Investment [Line Items]
Percentage of installment premiums denominated in currencies other than the U.S. dollar	8.00%	9.00%

Insurance_Company_Regulatory_R2

Insurance Company Regulatory Requirements - Narrative (Details) (USD $)	3 Months Ended					12 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2014		Sep. 30, 2013	Dec. 31, 2014		Dec. 31, 2013		Jul. 16, 2013
Assured Guaranty Re [Member]
Statutory Accounting Practices [Line Items]
Policyholders' surplus			$1,114,000,000			$1,114,000,000		$1,119,000,000
AGM and AGC [Member]
Statutory Accounting Practices [Line Items]
Contingency reserves reassumed, release of assets		130,000,000
Contingency reserves reassumed, percentage	50.00%	33.00%
Reassumed contingency reserves	244,000,000
Contingency reserves, release of assets	274,000,000
Assured Guaranty Europe Ltd [Member]
Statutory Accounting Practices [Line Items]
Contingency reserves reassumed, percentage			83.00%
Reassumed contingency reserves			24,500,000
AGC [Member]
Statutory Accounting Practices [Line Items]
Policyholders' surplus			1,086,000,000	[1]		1,086,000,000	[1]	693,000,000	[1]
Payments for interest in subsidiary					275,000,000
Intercompany, ceded premiums					24,000,000,000
Intercompany, ceded unearned premiums					249,000,000
Contingency reserves, release of assets						540,000,000
MAC [Member]
Statutory Accounting Practices [Line Items]
Policyholders' surplus			612,000,000			612,000,000		514,000,000		800,000,000
Assured Guaranty (Bermuda) Ltd (AGBM) [Member]
Statutory Accounting Practices [Line Items]
Surplus notes										82,500,000
Municipal Assurance Corp Holdings [Member]
Statutory Accounting Practices [Line Items]
Policyholders' surplus										400,000,000
Surplus notes										300,000,000
AGM [Member]
Statutory Accounting Practices [Line Items]
Policyholders' surplus			2,267,000,000	[1]		2,267,000,000	[1]	1,733,000,000	[1]
Payments for interest in subsidiary					425,000,000
Intercompany, ceded premiums					87,000,000,000
Intercompany, ceded unearned premiums					468,000,000
Contingency reserves, release of assets						588,000,000
AGM [Member] | AGM [Member]
Statutory Accounting Practices [Line Items]
Surplus notes										100,000,000
Subsidiaries [Member] | Municipal Assurance Corp Holdings [Member] | AGM [Member]
Statutory Accounting Practices [Line Items]
Holding company's percent ownership of common stock										61.00%
Subsidiaries [Member] | Municipal Assurance Corp Holdings [Member] | MAC [Member]
Statutory Accounting Practices [Line Items]
Holding company's percent ownership of common stock										100.00%
Subsidiaries [Member] | Municipal Assurance Corp Holdings [Member] | AGC [Member]
Statutory Accounting Practices [Line Items]
Holding company's percent ownership of common stock										39.00%
New York [Member] | Assured Guaranty (Europe) and Assured Guaranty Municipal Corp. [Member]
Statutory Accounting Practices [Line Items]
Contingency reserves reassumed, amount								250,000,000
Contingency reserves reassumed, year two, percentage								50.00%
Contingency reserves reassumed, year three, percentage								17.00%
Contingency reserves reassumed, percentage								33.00%
New York [Member] | AGM [Member]
Statutory Accounting Practices [Line Items]
Threshold for dividend payments as a percentage of policyholder surplus						10.00%
Threshold for dividend payments, percentage of adjusted net investment income						100.00%
Amount available for distribution, current year			227,000,000			227,000,000
Amount available for distribution, next fiscal quarter			67,000,000			67,000,000
MARYLAND | AGC [Member]
Statutory Accounting Practices [Line Items]
Contingency reserves reassumed, year two, percentage								50.00%
Contingency reserves reassumed, year three, percentage								17.00%
Contingency reserves reassumed, percentage								33.00%
Threshold for dividend payments as a percentage of policyholder surplus						10.00%
Threshold for dividend payments, percentage of adjusted net investment income						100.00%
Amount available for distribution, current year			21,000,000			21,000,000
Reassumed contingency reserves								267,000,000
MARYLAND | AGUS [Member] | AGC [Member]
Statutory Accounting Practices [Line Items]
Dividend restrictions on outstanding statutory surplus			90,000,000			90,000,000
Bermuda [Member] | Assured Guaranty Re [Member]
Statutory Accounting Practices [Line Items]
Unencumbered assets			651,000,000			651,000,000
Dividend Payment Restrictions Schedule, Percentage of Statutory Capital						15.00%
Statutory surplus			271,000,000			271,000,000
Dividend restrictions on outstanding statutory surplus			279,000,000			279,000,000
Dividend Payment Restrictions Schedule Amount of Statutory Capital						$127,000,000
Dividend restrictions on statutory capital and surplus (as a percent)						25.00%
Minimum [Member]
Statutory Accounting Practices [Line Items]
Rate at which present value of expected losses are discounted (as a percent)			4.50%			4.50%
Maximum [Member]
Statutory Accounting Practices [Line Items]
Rate at which present value of expected losses are discounted (as a percent)			5.00%			5.00%
[1]	Policyholders' surplus of AGM and AGC include their indirect share of MAC. AGM and AGC own approximately 61% and 39%, respectively, of the outstanding stock of Municipal Assurance Holdings Inc. ("MAC Holdings"), which owns 100% of the outstanding common stock of MAC.

Insurance_Company_Regulatory_R3

Insurance Company Regulatory Requirements - Insurance Regulatory Amounts Reported (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Jul. 16, 2013
AGM [Member]
Statutory Accounting Practices [Line Items]
Policyholders' surplus	$2,267	[1]	$1,733	[1]
Net Income (Loss)	304	[1]	340	[1]	203	[1]
MAC [Member]
Statutory Accounting Practices [Line Items]
Policyholders' surplus	612		514				800
Net Income (Loss)	75		26		1
AGC [Member]
Statutory Accounting Practices [Line Items]
Policyholders' surplus	1,086	[1]	693	[1]
Net Income (Loss)	116	[1]	211	[1]	31	[1]
Assured Guaranty Re [Member]
Statutory Accounting Practices [Line Items]
Policyholders' surplus	1,114		1,119
Net Income (Loss)	$28		$103		$117
[1]	Policyholders' surplus of AGM and AGC include their indirect share of MAC. AGM and AGC own approximately 61% and 39%, respectively, of the outstanding stock of Municipal Assurance Holdings Inc. ("MAC Holdings"), which owns 100% of the outstanding common stock of MAC.

Insurance_Company_Regulatory_R4

Insurance Company Regulatory Requirements - Dividends and Surplus Notes By Insurance Company Subsidiaries (Details) (Affiliated Entity [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Municipal Assurance Corp Holdings [Member] | MAC [Member]
Statutory Accounting Practices [Line Items]
Issuance of surplus notes	$0	($300)	$0
AGM [Member] | MAC [Member]
Statutory Accounting Practices [Line Items]
Issuance of surplus notes	0	-100	0
Assured Guaranty LTD [Member] | Assured Guaranty Re [Member]
Statutory Accounting Practices [Line Items]
Dividends paid	82	144	151
AGMH [Member] | AGM [Member]
Statutory Accounting Practices [Line Items]
Dividends paid	160	163	30
Repayment of surplus notes	50	50	50
AGUS [Member] | AGC [Member]
Statutory Accounting Practices [Line Items]
Dividends paid	$69	$67	$55

Income_Taxes_Effective_Tax_Rat

Income Taxes - Effective Tax Rate Reconciliation and Pretax Income (Loss) and Revenue by Tax Jurisdiction (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pre-tax Income Taxes and Revenue [Line Items]
Expected tax provision (benefit) at statutory rates in taxable jurisdictions									$490	$390	$76
Tax-exempt interest									-53	-57	-61
Change in liability for uncertain tax positions									9	-2	2
Other									-3	3	5
Total provision (benefit) for income taxes	224	133	59	27	140	152	110	-68	443	334	22
Effective tax rate (as a percent)									28.90%	29.20%	16.50%
Income (loss) before provision for income taxes	756	488	218	69	489	536	329	-212	1,531	1,142	132
Revenue									1,994	1,608	954
United States [Member]
Pre-tax Income Taxes and Revenue [Line Items]
Income (loss) before provision for income taxes									1,420	1,118	218
Revenue									1,633	1,389	875
Bermuda [Member]
Pre-tax Income Taxes and Revenue [Line Items]
Income (loss) before provision for income taxes									142	27	-86
Revenue									365	219	79
United Kingdom [Member]
Pre-tax Income Taxes and Revenue [Line Items]
Income (loss) before provision for income taxes									-31	-3	0
Revenue									($4)	$0	$0

Income_Taxes_Components_of_Net

Income Taxes - Components of Net Deferred Tax Assets (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Deferred tax assets:
Unrealized losses on credit derivative financial instruments, net	$224	$402
Unearned premium reserves, net	63	63
Loss and LAE reserve	66	134
Tax and loss bonds	39	33
Alternative minimum tax credit	57	90
Foreign tax credit	0	37
FG VIEs	13	29
DAC	35	40
Investment basis difference	104	93
Deferred compensation	38	33
Other	19	21
Total deferred income tax assets	658	975
Deferred tax liabilities:
Contingency reserves	64	47
Public debt	96	98
Unrealized appreciation on investments	159	68
Unrealized gains on CCS	22	16
Market discount	36	24
Other	21	34
Total deferred income tax liabilities	398	287
Net deferred income tax asset	$260	$688

Income_Taxes_Uncertain_Tax_Pos

Income Taxes - Uncertain Tax Positions (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of January 1,	$20	$22	$20
True-up from tax return filings	6	4	0
Increase in unrecognized tax benefits as a result of position taken during the current period	2	3	2
Decrease due to closing of IRS audit	0	-9	0
Balance as of December 31,	$28	$20	$22

Income_Taxes_Narrative_Details

Income Taxes - Narrative (Details) (USD $)	12 Months Ended			9 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Mar. 31, 2014	Mar. 31, 2013
Income Taxes [Line Items]
Corporate tax rate	35.00%
Realization assessment period	3 years
Interest and penalties related to uncertain tax positions	$1	$1	$1
Accrued interest and penalties, uncertain tax positions	4.5	3.5		4.5
Unrecognized tax benefits that would impact effective tax rate	28			28
Liability under tax allocation agreement	4	5		4
Reduction in liability for tax basis step-up adjustment	1
AGRO
Income Taxes [Line Items]
Operating loss carryforwards	6	13		6
United Kingdom [Member]
Income Taxes [Line Items]
Corporate tax rate	21.00%
Value added tax rate	20.00%
UNITED KINGDOM
Income Taxes [Line Items]
Corporate tax rate	21.50%	23.25%		21.00%	23.00%	24.00%
April 1, 2014 to April 1, 2015 | United Kingdom [Member]
Income Taxes [Line Items]
Corporate tax rate	21.00%
Subsequent to April 1, 2015 | United Kingdom [Member]
Income Taxes [Line Items]
Corporate tax rate	20.00%
Alternative Minimum Tax Credit Carryforward [Member]
Income Taxes [Line Items]
Foreign tax credit	$57			57

Reinsurance_and_Other_Monoline2

Reinsurance and Other Monoline Exposures - Net Effect of Commutations of Ceded and Cancellations of Assumed Reinsurance Contracts (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Insurance [Abstract]
Increase (decrease) in net unearned premium reserve	$20	$11	$109
Increase (decrease) in net par outstanding	1,167	151	19,173
Commutation gains recorded in other income	$23	$2	$82

Reinsurance_and_Other_Monoline3

Reinsurance and Other Monoline Exposures - Effect of Reinsurance on Statement of Operations (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Premiums Written:
Direct									$116		$106		$244
Assumed									-12	[1]	17	[1]	9	[1]
Ceded									15	[2]	2	[2]	51	[2]
Net									119		125		304
Premiums Earned:
Direct									581		819		936
Assumed									47		40		50
Ceded									-58		-107		-133
Net earned premiums	158	144	136	132	182	159	163	248	570		752		853
Loss and LAE:
Direct									132		110		636
Assumed									37		73		-4
Ceded									-43		-29		-128
Loss and LAE	$72	($44)	$57	$41	$85	$55	$62	($48)	$126		$154		$504
[1]	Negative assumed premiums written were due to cancellations and changes in expected Debt Service schedules.
[2]	Positive ceded premiums written were due to commutations and changes in expected Debt Service schedules.

Reinsurance_and_Other_Monoline4

Reinsurance and Other Monoline Exposures - Exposure by Reinsurer (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	$22,975	[1]	$28,788
Second-to- Pay Insured Par Outstanding	18,469	[1],[2]
Assumed Par Outstanding	27,886	[1]
American Overseas Reinsurance Company Limited (f/k/a Ram Re) [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	6,727	[1]
Second-to- Pay Insured Par Outstanding	0	[1]
Assumed Par Outstanding	30	[1]
Tokio Marine & Nichido Fire Insurance Co., Ltd. (“Tokio”) [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	5,276	[1]
Second-to- Pay Insured Par Outstanding	0	[1]
Assumed Par Outstanding	0	[1]
Radian [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	4,104	[1]
Second-to- Pay Insured Par Outstanding	21	[1],[2]
Assumed Par Outstanding	671	[1]
Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	3,715	[1]
Second-to- Pay Insured Par Outstanding	1,514	[1],[2]
Assumed Par Outstanding	161	[1]
Mitsui Sumitomo Insurance Co. Ltd. [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	2,033	[1]
Second-to- Pay Insured Par Outstanding	0	[1]
Assumed Par Outstanding	0	[1]
Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	746	[1]
Second-to- Pay Insured Par Outstanding	2	[1],[2]
Assumed Par Outstanding	0	[1]
Swiss Reinsurance Co. [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	93	[1]
Second-to- Pay Insured Par Outstanding	0	[1]
Assumed Par Outstanding	0	[1]
Ambac [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	82	[1]
Second-to- Pay Insured Par Outstanding	4,930	[1],[2]
Assumed Par Outstanding	14,342	[1]
National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	0	[1]
Second-to- Pay Insured Par Outstanding	6,210	[1],[2]
Assumed Par Outstanding	5,894	[1]
MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	0	[1]
Second-to- Pay Insured Par Outstanding	2,613	[1],[2]
Assumed Par Outstanding	587	[1]
FGIC [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	0	[1]
Second-to- Pay Insured Par Outstanding	2,074	[1],[2]
Assumed Par Outstanding	834	[1]
Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	0	[1]
Second-to- Pay Insured Par Outstanding	109	[1],[2]
Assumed Par Outstanding	956	[1]
CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	0	[1]
Second-to- Pay Insured Par Outstanding	102	[1],[2]
Assumed Par Outstanding	4,365	[1]
Other [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	199	[1]
Second-to- Pay Insured Par Outstanding	894	[1],[2]
Assumed Par Outstanding	$46	[1]
[1]	Includes par related to insured credit derivatives.
[2]	Assured Guaranty’s internal rating.

Reinsurance_and_Other_Monoline5

Reinsurance and Other Monoline Exposures - Exposure by Credit Rating (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Ceded Credit Risk [Line Items]
Ceded Par Amount	$22,975	[1]	$28,788
Internal Credit Rating, AAA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	1,798
Internal Credit Rating, AA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	5,207
Internal Credit Rating, A [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	7,168
Internal Credit Rating, BBB [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	6,053
BIG [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	2,749
American Overseas Reinsurance Company Limited (f/k/a Ram Re) [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	6,727	[1]
American Overseas Reinsurance Company Limited (f/k/a Ram Re) [Member] | Internal Credit Rating, AAA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	633
American Overseas Reinsurance Company Limited (f/k/a Ram Re) [Member] | Internal Credit Rating, AA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	2,452
American Overseas Reinsurance Company Limited (f/k/a Ram Re) [Member] | Internal Credit Rating, A [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	1,992
American Overseas Reinsurance Company Limited (f/k/a Ram Re) [Member] | Internal Credit Rating, BBB [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	1,158
American Overseas Reinsurance Company Limited (f/k/a Ram Re) [Member] | BIG [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	492
Tokio Marine & Nichido Fire Insurance Co., Ltd. (“Tokio”) [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	5,276	[1]
Tokio Marine & Nichido Fire Insurance Co., Ltd. (“Tokio”) [Member] | Internal Credit Rating, AAA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	763
Tokio Marine & Nichido Fire Insurance Co., Ltd. (“Tokio”) [Member] | Internal Credit Rating, AA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	968
Tokio Marine & Nichido Fire Insurance Co., Ltd. (“Tokio”) [Member] | Internal Credit Rating, A [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	1,485
Tokio Marine & Nichido Fire Insurance Co., Ltd. (“Tokio”) [Member] | Internal Credit Rating, BBB [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	1,281
Tokio Marine & Nichido Fire Insurance Co., Ltd. (“Tokio”) [Member] | BIG [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	779
Radian [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	4,104	[1]
Radian [Member] | Internal Credit Rating, AAA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	206
Radian [Member] | Internal Credit Rating, AA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	287
Radian [Member] | Internal Credit Rating, A [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	2,037
Radian [Member] | Internal Credit Rating, BBB [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	1,085
Radian [Member] | BIG [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	489
Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	3,715	[1]
Syncora Guarantee Inc. [Member] | Internal Credit Rating, AAA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	0
Syncora Guarantee Inc. [Member] | Internal Credit Rating, AA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	291
Syncora Guarantee Inc. [Member] | Internal Credit Rating, A [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	498
Syncora Guarantee Inc. [Member] | Internal Credit Rating, BBB [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	2,193
Syncora Guarantee Inc. [Member] | BIG [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	733
Mitsui Sumitomo Insurance Co. Ltd. [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	2,033	[1]
Mitsui Sumitomo Insurance Co. Ltd. [Member] | Internal Credit Rating, AAA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	134
Mitsui Sumitomo Insurance Co. Ltd. [Member] | Internal Credit Rating, AA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	669
Mitsui Sumitomo Insurance Co. Ltd. [Member] | Internal Credit Rating, A [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	742
Mitsui Sumitomo Insurance Co. Ltd. [Member] | Internal Credit Rating, BBB [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	299
Mitsui Sumitomo Insurance Co. Ltd. [Member] | BIG [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	189
Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	746	[1]
Aca Financial Guaranty Corp [Member] | Internal Credit Rating, AAA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	0
Aca Financial Guaranty Corp [Member] | Internal Credit Rating, AA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	458
Aca Financial Guaranty Corp [Member] | Internal Credit Rating, A [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	277
Aca Financial Guaranty Corp [Member] | Internal Credit Rating, BBB [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	11
Aca Financial Guaranty Corp [Member] | BIG [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	0
Swiss Reinsurance Co. [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	93	[1]
Swiss Reinsurance Co. [Member] | Internal Credit Rating, AAA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	0
Swiss Reinsurance Co. [Member] | Internal Credit Rating, AA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	0
Swiss Reinsurance Co. [Member] | Internal Credit Rating, A [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	0
Swiss Reinsurance Co. [Member] | Internal Credit Rating, BBB [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	26
Swiss Reinsurance Co. [Member] | BIG [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	67
Ambac [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	82	[1]
Ambac [Member] | Internal Credit Rating, AAA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	0
Ambac [Member] | Internal Credit Rating, AA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	0
Ambac [Member] | Internal Credit Rating, A [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	82
Ambac [Member] | Internal Credit Rating, BBB [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	0
Ambac [Member] | BIG [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	0
Other [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	199	[1]
Other [Member] | Internal Credit Rating, AAA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	62
Other [Member] | Internal Credit Rating, AA [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	82
Other [Member] | Internal Credit Rating, A [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	55
Other [Member] | Internal Credit Rating, BBB [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	0
Other [Member] | BIG [Member]
Ceded Credit Risk [Line Items]
Ceded Par Amount	$0
[1]	Includes par related to insured credit derivatives.

Reinsurance_and_Other_Monoline6

Reinsurance and Other Monoline Exposures - Second-to-Pay Insured Par Outstanding by Internal Rating (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	$18,469	[1],[2]
Radian [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	21	[1],[2]
Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	1,514	[1],[2]
Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	2	[1],[2]
Ambac [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	4,930	[1],[2]
National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	6,210	[1],[2]
MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	2,613	[1],[2]
FGIC [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	2,074	[1],[2]
Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	109	[1],[2]
CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	102	[1],[2]
Other [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	894	[1],[2]
Public Finance [Member] | Internal Credit Rating, AAA [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	190	[1]
Public Finance [Member] | Internal Credit Rating, AAA [Member] | Radian [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, AAA [Member] | Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, AAA [Member] | Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, AAA [Member] | Ambac [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	30	[1]
Public Finance [Member] | Internal Credit Rating, AAA [Member] | National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	160	[1]
Public Finance [Member] | Internal Credit Rating, AAA [Member] | MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, AAA [Member] | FGIC [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, AAA [Member] | Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, AAA [Member] | CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, AAA [Member] | Other [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, AA [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	4,580	[1]
Public Finance [Member] | Internal Credit Rating, AA [Member] | Radian [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, AA [Member] | Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	45	[1]
Public Finance [Member] | Internal Credit Rating, AA [Member] | Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	1	[1]
Public Finance [Member] | Internal Credit Rating, AA [Member] | Ambac [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	1,301	[1]
Public Finance [Member] | Internal Credit Rating, AA [Member] | National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	2,193	[1]
Public Finance [Member] | Internal Credit Rating, AA [Member] | MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	65	[1]
Public Finance [Member] | Internal Credit Rating, AA [Member] | FGIC [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	77	[1]
Public Finance [Member] | Internal Credit Rating, AA [Member] | Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, AA [Member] | CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	4	[1]
Public Finance [Member] | Internal Credit Rating, AA [Member] | Other [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	894	[1]
Public Finance [Member] | Internal Credit Rating, A [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	8,039	[1]
Public Finance [Member] | Internal Credit Rating, A [Member] | Radian [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	3	[1]
Public Finance [Member] | Internal Credit Rating, A [Member] | Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	326	[1]
Public Finance [Member] | Internal Credit Rating, A [Member] | Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, A [Member] | Ambac [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	2,597	[1]
Public Finance [Member] | Internal Credit Rating, A [Member] | National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	3,833	[1]
Public Finance [Member] | Internal Credit Rating, A [Member] | MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	254	[1]
Public Finance [Member] | Internal Credit Rating, A [Member] | FGIC [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	975	[1]
Public Finance [Member] | Internal Credit Rating, A [Member] | Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, A [Member] | CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	51	[1]
Public Finance [Member] | Internal Credit Rating, A [Member] | Other [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, BBB [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	2,104	[1]
Public Finance [Member] | Internal Credit Rating, BBB [Member] | Radian [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	12	[1]
Public Finance [Member] | Internal Credit Rating, BBB [Member] | Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	727	[1]
Public Finance [Member] | Internal Credit Rating, BBB [Member] | Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	1	[1]
Public Finance [Member] | Internal Credit Rating, BBB [Member] | Ambac [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	637	[1]
Public Finance [Member] | Internal Credit Rating, BBB [Member] | National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, BBB [Member] | MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	424	[1]
Public Finance [Member] | Internal Credit Rating, BBB [Member] | FGIC [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	281	[1]
Public Finance [Member] | Internal Credit Rating, BBB [Member] | Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | Internal Credit Rating, BBB [Member] | CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	22	[1]
Public Finance [Member] | Internal Credit Rating, BBB [Member] | Other [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | BIG [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	672	[1]
Public Finance [Member] | BIG [Member] | Radian [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	6	[1]
Public Finance [Member] | BIG [Member] | Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	276	[1]
Public Finance [Member] | BIG [Member] | Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | BIG [Member] | Ambac [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	63	[1]
Public Finance [Member] | BIG [Member] | National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | BIG [Member] | MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | BIG [Member] | FGIC [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	302	[1]
Public Finance [Member] | BIG [Member] | Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Public Finance [Member] | BIG [Member] | CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	25	[1]
Public Finance [Member] | BIG [Member] | Other [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AAA [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	467	[1]
Structured Finance [Member] | Internal Credit Rating, AAA [Member] | Radian [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AAA [Member] | Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	96	[1]
Structured Finance [Member] | Internal Credit Rating, AAA [Member] | Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AAA [Member] | Ambac [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AAA [Member] | National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AAA [Member] | MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AAA [Member] | FGIC [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	371	[1]
Structured Finance [Member] | Internal Credit Rating, AAA [Member] | Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AAA [Member] | CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AAA [Member] | Other [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AA [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	1,542	[1]
Structured Finance [Member] | Internal Credit Rating, AA [Member] | Radian [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AA [Member] | Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AA [Member] | Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AA [Member] | Ambac [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	1	[1]
Structured Finance [Member] | Internal Credit Rating, AA [Member] | National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AA [Member] | MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	1,508	[1]
Structured Finance [Member] | Internal Credit Rating, AA [Member] | FGIC [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AA [Member] | Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	33	[1]
Structured Finance [Member] | Internal Credit Rating, AA [Member] | CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, AA [Member] | Other [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, A [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	113	[1]
Structured Finance [Member] | Internal Credit Rating, A [Member] | Radian [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, A [Member] | Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, A [Member] | Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, A [Member] | Ambac [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	64	[1]
Structured Finance [Member] | Internal Credit Rating, A [Member] | National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	24	[1]
Structured Finance [Member] | Internal Credit Rating, A [Member] | MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, A [Member] | FGIC [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	25	[1]
Structured Finance [Member] | Internal Credit Rating, A [Member] | Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, A [Member] | CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, A [Member] | Other [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, BBB [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	474	[1]
Structured Finance [Member] | Internal Credit Rating, BBB [Member] | Radian [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, BBB [Member] | Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, BBB [Member] | Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, BBB [Member] | Ambac [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	231	[1]
Structured Finance [Member] | Internal Credit Rating, BBB [Member] | National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, BBB [Member] | MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	243	[1]
Structured Finance [Member] | Internal Credit Rating, BBB [Member] | FGIC [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, BBB [Member] | Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, BBB [Member] | CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | Internal Credit Rating, BBB [Member] | Other [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | BIG [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	288	[1]
Structured Finance [Member] | BIG [Member] | Radian [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | BIG [Member] | Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	44	[1]
Structured Finance [Member] | BIG [Member] | Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | BIG [Member] | Ambac [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	6	[1]
Structured Finance [Member] | BIG [Member] | National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | BIG [Member] | MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	119	[1]
Structured Finance [Member] | BIG [Member] | FGIC [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	43	[1]
Structured Finance [Member] | BIG [Member] | Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	76	[1]
Structured Finance [Member] | BIG [Member] | CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	0	[1]
Structured Finance [Member] | BIG [Member] | Other [Member]
Ceded Credit Risk [Line Items]
Second-to- Pay Insured Par Outstanding	$0	[1]
[1]	Assured Guaranty’s internal rating.
[2]	Includes par related to insured credit derivatives.

Reinsurance_and_Other_Monoline7

Reinsurance and Other Monoline Exposures - Reinsurance and Other Monoline Exposures (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	$71
Ceded Premium, net of Commissions	-92
Assumed Expected Loss and LAE	-127
Ceded Expected Loss and LAE	101
American Overseas Reinsurance Company Limited (f/k/a Ram Re) [Member]
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	0
Ceded Premium, net of Commissions	-8
Assumed Expected Loss and LAE	0
Ceded Expected Loss and LAE	11
Tokio Marine & Nichido Fire Insurance Co., Ltd. (“Tokio”) [Member]
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	0
Ceded Premium, net of Commissions	-13
Assumed Expected Loss and LAE	0
Ceded Expected Loss and LAE	46
Radian [Member]
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	0
Ceded Premium, net of Commissions	-13
Assumed Expected Loss and LAE	0
Ceded Expected Loss and LAE	19
Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	0
Ceded Premium, net of Commissions	-29
Assumed Expected Loss and LAE	0
Ceded Expected Loss and LAE	4
Mitsui Sumitomo Insurance Co. Ltd. [Member]
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	0
Ceded Premium, net of Commissions	-3
Assumed Expected Loss and LAE	0
Ceded Expected Loss and LAE	15
Swiss Reinsurance Co. [Member]
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	0
Ceded Premium, net of Commissions	-3
Assumed Expected Loss and LAE	0
Ceded Expected Loss and LAE	6
Ambac [Member]
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	43
Ceded Premium, net of Commissions	0
Assumed Expected Loss and LAE	-19
Ceded Expected Loss and LAE	0
National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	7
Ceded Premium, net of Commissions	0
Assumed Expected Loss and LAE	-7
Ceded Expected Loss and LAE	0
MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	5
Ceded Premium, net of Commissions	0
Assumed Expected Loss and LAE	-9
Ceded Expected Loss and LAE	0
FGIC [Member]
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	5
Ceded Premium, net of Commissions	0
Assumed Expected Loss and LAE	-3
Ceded Expected Loss and LAE	0
Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	13
Ceded Premium, net of Commissions	0
Assumed Expected Loss and LAE	-83
Ceded Expected Loss and LAE	0
CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	0
Ceded Premium, net of Commissions	0
Assumed Expected Loss and LAE	-6
Ceded Expected Loss and LAE	0
Other [Member]
Ceded Credit Risk [Line Items]
Assumed Premium, net of Commissions	-2
Ceded Premium, net of Commissions	-23
Assumed Expected Loss and LAE	0
Ceded Expected Loss and LAE	$0

Reinsurance_and_Other_Monoline8

Reinsurance and Other Monoline Exposures - Narrative (Details) (USD $)	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 24, 2012	Jan. 01, 2014
Ceded Credit Risk [Line Items]
Fixed-maturity securities	$11,258,000,000	$10,615,000,000
Commutation gains recorded in other income	23,000,000	2,000,000	82,000,000
Non-affiliated Reinsurers [Member]
Ceded Credit Risk [Line Items]
Collateral posted by non-affiliated reinsurers	610,000,000
Radian [Member]
Ceded Credit Risk [Line Items]
Approximate amount of insurance risk agreed to be assumed				1,800,000,000
Payment Received for Assumed Insured Risk				22,000,000
Assured Guaranty Re [Member]
Ceded Credit Risk [Line Items]
Amounts could be required to pay if third party exercised right to recapture business	85,000,000
AGC [Member]
Ceded Credit Risk [Line Items]
Amounts could be required to pay if third party exercised right to recapture business	45,000,000
Fixed Maturities [Member]
Ceded Credit Risk [Line Items]
Fixed-maturity securities	10,491,000,000	9,711,000,000
Fixed Maturities [Member] | National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Fixed-maturity securities	330,000,000
Fixed Maturities [Member] | Ambac [Member]
Ceded Credit Risk [Line Items]
Fixed-maturity securities	266,000,000
Fixed Maturities [Member] | Other [Member]
Ceded Credit Risk [Line Items]
Fixed-maturity securities	29,000,000
Excess of Loss Reinsurance Facility [Member] | AGM, AGC and MAC [Member]
Ceded Credit Risk [Line Items]
Minimum net losses required for attachment of excess of loss reinsurance facility					1,500,000,000
Amount of losses covered under the facility					500,000,000
Reinsurance retention policy, excess retention, amount reinsured					450,000,000
Remaining amount of losses covered under the facility					50,000,000
Premiums paid during the period	19,000,000
Remaining insurance premium payable	$19,000,000

Related_Party_Transactions_Det

Related Party Transactions (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Net expenses from transactions with related parties	$1,900,000	$2,500,000	$3,400,000
Maximum [Member]
Related Party Transaction [Line Items]
Net expenses from transactions with related parties	$1,900,000	$1,900,000	$2,000,000
Common Stock [Member] | Wilbur L Ross [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners		8.20%	10.20%
Common Stock [Member] | Wellington Management Company LLP [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	9.30%	6.60%	8.60%

Commitments_and_Contingencies_1

Commitments and Contingencies - Future Minimum Rental Payments (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2015	$8
2016	8
2017	8
2018	8
2019	8
Thereafter	52
Total	$92

Commitments_and_Contingencies_2

Commitments and Contingencies - Narrative (Details) (USD $)

12 Months Ended

1 Months Ended

0 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

0 Months Ended

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Sep. 30, 2009

Jul. 31, 2010

Nov. 19, 2012

Dec. 31, 2008

31-May-10

Apr. 30, 2010

Dec. 31, 2009

Jan. 30, 2015

Nov. 28, 2011

Sep. 25, 2013

Lawsuit

Plaintiff

Person

Lawsuit

Lawsuit

Lawsuit

Lawsuit

Transaction

Commitments and Contingencies Legal Proceedings

Rent expense

$10,100,000

$9,900,000

$10,000,000

Minimum Number of Proceedings for Recoveries to Have Potential Material Impact

1

Governmental Investigations [Member]

Commitments and Contingencies Legal Proceedings

Number of plaintiffs filing consolidated complaints

4

AGMH [Member] | Governmental Investigations [Member]

Commitments and Contingencies Legal Proceedings

Number of persons indicted who worked at Financial Guaranty Insurance Company

2

Number of persons convicted of conspiracy and fraud who worked at Financial Guaranty Insurance Company

2

LBIE vs. AG Financial Products [Member] | AG Financial Products Inc. [Member] | Guarantee Obligations [Member]

Commitments and Contingencies Legal Proceedings

Number of credit derivative transactions for which termination payment is alleged to be improperly calculated

9

Number of credit derivative transactions alleged to be improperly terminated

28

Pending Litigation | LBIE vs. AG Financial Products [Member] | AG Financial Products Inc. [Member]

Commitments and Contingencies Legal Proceedings

Termination payments which LBIE owes to AG Financial Products as per calculation of AG Financial Products

30,000,000

Termination payments which AG Financial Products owes to LBIE as per calculation of LBIE

1,400,000,000

Pending Litigation | LBHI and LBSF vs CPT 283, FSA and AGM [Member] | AGM [Member]

Commitments and Contingencies Legal Proceedings

Termination payments which LBIE owes to AG Financial Products as per calculation of AG Financial Products

43,800,000

Termination payments which AG Financial Products and CPT 283 owes to LBHI and LBSF as per calculation of LBHI and LBSF

67,300,000

Pending Litigation | LBHI and LBSF vs CPT 207, FSA and AGM [Member] | AGM [Member]

Commitments and Contingencies Legal Proceedings

Termination payments which LBIE owes to AG Financial Products as per calculation of AG Financial Products

492,555

Termination payments which AG Financial Products and CPT 283 owes to LBHI and LBSF as per calculation of LBHI and LBSF

1,500,000

Pending Litigation | Wells Fargo Bank, N.A., Interpleader Complaint [Member] | AGM [Member]

Commitments and Contingencies Legal Proceedings

Increase in losses as a result of an adverse outcome, minimum

10,000,000

Increase in losses as a result of an adverse outcome, maximum

20,000,000

Pending Litigation | MDL 1950 [Member]

Commitments and Contingencies Legal Proceedings

Number of putative class action lawsuits filed in federal court

9

Pending Litigation | MDL 1950 [Member] | AGMH [Member]

Commitments and Contingencies Legal Proceedings

Number of putative class action lawsuits filed in federal court

4

Pending Litigation | MDL 1950 [Member] | AGM and AGMH [Member]

Commitments and Contingencies Legal Proceedings

Number of putative class action lawsuits filed in federal court

5

Pending Litigation | Non-class Action Cases Consolidated with MDL 1950 for Pretrial Proceedings [Member] | AGM and AGMH [Member] | Proceedings Related to Former Financial Products Business [Member]

Commitments and Contingencies Legal Proceedings

Number of putative class action lawsuits filed in federal court

5

Pending Litigation | Non-class Action Cases Consolidated with MDL 1950 for Pretrial Proceedings [Member] | AGM and AGUS [Member] | Proceedings Related to Former Financial Products Business [Member]

Commitments and Contingencies Legal Proceedings

Number of putative class action lawsuits filed in federal court

5

6

Number of non-class action lawsuits for which dismissal was denied

11

Subsequent Event [Member] | Settled Litigation [Member] | LBHI and LBSF vs CPT 207, FSA and AGM [Member] | AGM [Member]

Commitments and Contingencies Legal Proceedings

Total allowed claim in bankruptcy

$20,000,000

LongTerm_Debt_and_Credit_Facil2

Long-Term Debt and Credit Facilities - Narrative (Details) (USD $)

1 Months Ended

0 Months Ended

12 Months Ended

0 Months Ended

Jun. 30, 2003

Apr. 07, 2008

Nov. 22, 2006

Dec. 31, 2014

Jul. 31, 2003

Nov. 26, 2002

18-May-04

Jun. 20, 2014

Jun. 24, 2009

Jun. 01, 2012

Dec. 31, 2013

Apr. 08, 2008

Apr. 08, 2005

Jun. 30, 2009

Oct. 25, 2013

Dec. 19, 2001

Dec. 20, 2006

Jun. 30, 2014

Jul. 01, 2009

Trust

extension

Trust

Debt Instrument [Line Items]

Aggregate principal amount

$1,596,000,000

$1,114,000,000

Price per share of stock issued (in dollars per share)

12.85

[1]

AGC Trust Preferred Securities [Member]

Debt Instrument [Line Items]

Basis points

2.50%

1.10%

AGM Trust Preferred Securities [Member]

Debt Instrument [Line Items]

Basis points

2.00%

AGUS [Member]

Debt Instrument [Line Items]

Aggregate principal amount

850,000,000

350,000,000

AGM [Member]

Debt Instrument [Line Items]

Aggregate principal amount

16,000,000

34,000,000

AGM [Member] | AGM CPS securities [Member]

Debt Instrument [Line Items]

Maximum stock purchase obligation of each custodial trust

50,000,000

Aggregate maximum stock purchase obligation of the custodial trusts

200,000,000

Number of custodial trusts

4

Rate basis for income distributions

one-month LIBOR

Auction interval (in days)

28 days

AGC [Member] | AGM CPS securities [Member]

Debt Instrument [Line Items]

Maximum stock purchase obligation of each custodial trust

200,000,000

Aggregate maximum stock purchase obligation of the custodial trusts

50,000,000

Number of custodial trusts

4

Rate basis for income distributions

one-month LIBOR

AGMH [Member]

Debt Instrument [Line Items]

Aggregate principal amount

730,000,000

730,000,000

Junior Subordinated Debt [Member] | AGMH [Member]

Debt Instrument [Line Items]

Aggregate principal amount

300,000,000

300,000,000

Interest rate of debt (as a percent)

6.40%

Interest rate, added to base rate (as a percent)

2.22%

Debt issued

300,000,000

Number of times repayment date may be extended

4

Junior Subordinated Debt [Member] | Maximum [Member] | AGMH [Member]

Debt Instrument [Line Items]

Period for increments of repayment date extension

5 years

Line of Credit [Member] | Strip Coverage Facility [Member] | AGM [Member]

Debt Instrument [Line Items]

Cumulative strip par exposure terminated

1,400,000,000

Commitment amount

1,000,000,000

Covenant terms, additional net worth requirement under reduced borrowing capacity

0

Covenant terms, maximum debt-to-capital ratio

30.00%

Covenant terms, minimum net worth percentage

75.00%

Covenant terms, minimum percentage of aggregate consolidated net income (or loss)

25.00%

Line of Credit [Member] | Revolving Credit Facility [Member] | Wilbur L. Ross [Member]

Debt Instrument [Line Items]

Interest rate, as a percentage of Federal short-term or mid-term interest rate

100.00%

Notes Payable, Other Payables [Member] | AGM [Member]

Debt Instrument [Line Items]

Aggregate principal amount

16,000,000

34,000,000

Notes Payable 5.60 Percent [Member] | Notes Payable, Other Payables [Member] | AGMH [Member]

Debt Instrument [Line Items]

Aggregate principal amount

100,000,000

100,000,000

Interest rate of debt (as a percent)

5.60%

5.60%

Debt issued

100,000,000

6.25% Notes [Member] | Notes Payable, Other Payables [Member] | AGMH [Member]

Debt Instrument [Line Items]

Aggregate principal amount

230,000,000

230,000,000

Interest rate of debt (as a percent)

6.25%

6.25%

Debt issued

230,000,000

QUIBS 6.875 Percent [Member] | Corporate securities [Member] | AGMH [Member]

Debt Instrument [Line Items]

Aggregate principal amount

100,000,000

100,000,000

100,000,000

Interest rate of debt (as a percent)

6.88%

6.88%

Enhanced Junior Subordinated Debentures [Member] | Junior Subordinated Debt [Member] | AGUS [Member]

Debt Instrument [Line Items]

Aggregate principal amount

150,000,000

Interest rate, added to base rate (as a percent)

2.38%

Enhanced Junior Subordinated Debentures [Member] | Junior Subordinated Debt [Member] | AGMH [Member]

Debt Instrument [Line Items]

Number of times interest payment may be deferred

1

Number of consecutive periods for which interest payments may be deferred

1

Period for which interest payment may be deferred (in years)

10 years

Period prior to final repayment date before which debt cannot be repaid, redeemed, repurchased or defeased (in years)

20 years

Senior Notes 8.50 Percent [Member] | Senior Notes [Member] | AGUS [Member]

Debt Instrument [Line Items]

Aggregate principal amount

173,000,000

Interest rate of debt (as a percent)

8.50%

8.50%

Principal amount of debt for percentage of undivided beneficial ownership interest per equity unit

1,000

Repurchase of debt, percent of principal amount

100.00%

Senior Notes 7.0 Percent [Member] | Senior Notes [Member] | AGUS [Member]

Debt Instrument [Line Items]

Aggregate principal amount

200,000,000

200,000,000

200,000,000

Net proceeds from issuance of debt

197,000,000

Interest rate of debt (as a percent)

7.00%

7.00%

7.00%

Effective interest rate of debt (as a percent)

6.40%

Senior Notes 5.0 Percent [Member] | Senior Notes [Member] | AGUS [Member]

Debt Instrument [Line Items]

Aggregate principal amount

500,000,000

500,000,000

0

Net proceeds from issuance of debt

495,000,000

Interest rate of debt (as a percent)

5.00%

0.00%

Intercompany Credit Facility [Member] | Line of Credit [Member] | Revolving Credit Facility [Member] | Wilbur L. Ross [Member] | AGL [Member]

Debt Instrument [Line Items]

Related party, maximum borrowing capacity

225,000,000

Registered Public Offering [Member] | Senior Notes 8.50 Percent [Member] | Senior Notes [Member] | AGUS [Member]

Debt Instrument [Line Items]

Shares issued

3,450,000

Proceeds from sales issued

167,000,000

Percentage of undivided beneficial ownership interest in debt principal per equity unit

5.00%

Price for which shares are issuable under forward purchase contract for each equity unit

50

Satisfaction of Forward Purchase Contract Obligation [Member] | AGL [Member]

Debt Instrument [Line Items]

AGL common shares issued for each $50 of proceeds received from remarketing Senior Notes

3.8924

Settlement rate in common shares after anti-dilution adjustments

3.8685

Common shares issued

13,428,770

Common Stock [Member] | Satisfaction of Forward Purchase Contract Obligation [Member] | AGL [Member]

Debt Instrument [Line Items]

Price per share of stock issued (in dollars per share)

12.85

Structured Finance [Member] | Financial Guarantee [Member] | AGM [Member]

Debt Instrument [Line Items]

Possible liquidity claims, gross exposure

1,200,000,000

Dexia Credit Local (NY) [Member] | Line of Credit [Member] | Strip Coverage Facility [Member] | AGM [Member]

Debt Instrument [Line Items]

Commitment amount

$495,000,000

$1,000,000,000

[1]

Relates to the settlement of forward purchase contracts. See Note 17, Long-Term Debt and Credit Facilities.

LongTerm_Debt_and_Credit_Facil3

Long-Term Debt and Credit Facilities - Principal and Carrying Amounts of Debt (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	18-May-04	Jun. 20, 2014	Dec. 19, 2001
Debt Instrument [Line Items]
Principal	$1,596,000,000	$1,114,000,000
Carrying Value	1,303,000,000	816,000,000
AGUS [Member]
Debt Instrument [Line Items]
Principal	850,000,000	350,000,000
Carrying Value	847,000,000	348,000,000
AGMH [Member]
Debt Instrument [Line Items]
Principal	730,000,000	730,000,000
Carrying Value	437,000,000	430,000,000
AGM [Member]
Debt Instrument [Line Items]
Principal	16,000,000	34,000,000
Carrying Value	19,000,000	38,000,000
Senior Notes [Member] | AGUS [Member] | Senior Notes 7.0 Percent [Member]
Debt Instrument [Line Items]
Interest rate of debt (as a percent)	7.00%	7.00%	7.00%
Principal	200,000,000	200,000,000	200,000,000
Carrying Value	198,000,000	198,000,000
Senior Notes [Member] | AGUS [Member] | Senior Notes 5.0 Percent [Member]
Debt Instrument [Line Items]
Interest rate of debt (as a percent)	5.00%	0.00%
Principal	500,000,000	0		500,000,000
Carrying Value	499,000,000	0
Enhanced Junior Subordinated Debentures [Member] | AGUS [Member]
Debt Instrument [Line Items]
Principal	150,000,000	150,000,000
Carrying Value	150,000,000	150,000,000
Corporate securities [Member] | AGMH [Member] | QUIBS 6.875 Percent [Member]
Debt Instrument [Line Items]
Interest rate of debt (as a percent)	6.88%	6.88%
Principal	100,000,000	100,000,000			100,000,000
Carrying Value	68,000,000	68,000,000
Notes Payable, Other Payables [Member] | AGMH [Member] | 6.25% Notes [Member]
Debt Instrument [Line Items]
Interest rate of debt (as a percent)	6.25%	6.25%
Principal	230,000,000	230,000,000
Carrying Value	139,000,000	138,000,000
Notes Payable, Other Payables [Member] | AGMH [Member] | Notes Payable 5.60 Percent [Member]
Debt Instrument [Line Items]
Interest rate of debt (as a percent)	5.60%	5.60%
Principal	100,000,000	100,000,000
Carrying Value	55,000,000	55,000,000
Notes Payable, Other Payables [Member] | AGM [Member]
Debt Instrument [Line Items]
Principal	16,000,000	34,000,000
Carrying Value	19,000,000	38,000,000
Junior Subordinated Debt [Member] | AGMH [Member]
Debt Instrument [Line Items]
Interest rate of debt (as a percent)	6.40%
Principal	300,000,000	300,000,000
Carrying Value	$175,000,000	$169,000,000

LongTerm_Debt_and_Credit_Facil4

Long-Term Debt and Credit Facilities - Expected Maturity Schedule of Debt (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Long-term Debt, Fiscal Year Maturity [Abstract]
2015	$7,000,000
2016	3,000,000
2017	3,000,000
2018	2,000,000
2019	1,000,000
2020-2039	700,000,000
2040-2059	0
2060-2079	450,000,000
Thereafter	430,000,000
Total	1,596,000,000	1,114,000,000
AGUS [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
2015	0
2016	0
2017	0
2018	0
2019	0
2020-2039	700,000,000
2040-2059	0
2060-2079	150,000,000
Thereafter	0
Total	850,000,000	350,000,000
AGMH [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
2015	0
2016	0
2017	0
2018	0
2019	0
2020-2039	0
2040-2059	0
2060-2079	300,000,000
Thereafter	430,000,000
Total	730,000,000	730,000,000
AGM [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
2015	7,000,000
2016	3,000,000
2017	3,000,000
2018	2,000,000
2019	1,000,000
2020-2039	0
2040-2059	0
2060-2079	0
Thereafter	0
Total	$16,000,000	$34,000,000

LongTerm_Debt_and_Credit_Facil5

Long-Term Debt and Credit Facilities - Interest Expense (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Interest expense	$92	$82	$92
AGUS [Member]
Debt Instrument [Line Items]
Interest expense	36	23	31
AGMH [Member]
Debt Instrument [Line Items]
Interest expense	54	54	54
AGM [Member]
Debt Instrument [Line Items]
Interest expense	2	5	7
Junior Subordinated Debt [Member] | AGMH [Member]
Debt Instrument [Line Items]
Interest expense	25	25	25
Corporate securities [Member] | AGMH [Member] | QUIBS 6.875 Percent [Member]
Debt Instrument [Line Items]
Interest expense	7	7	7
Senior Notes [Member] | AGUS [Member] | Senior Notes 7.0 Percent [Member]
Debt Instrument [Line Items]
Interest expense	13	13	13
Senior Notes [Member] | AGUS [Member] | Senior Notes 5.0 Percent [Member]
Debt Instrument [Line Items]
Interest expense	13	0	0
Senior Notes [Member] | AGUS [Member] | Senior Notes 8.50 Percent [Member]
Debt Instrument [Line Items]
Interest expense	0	0	8
Enhanced Junior Subordinated Debentures [Member] | AGUS [Member]
Debt Instrument [Line Items]
Interest expense	10	10	10
Notes Payable, Other Payables [Member] | AGMH [Member] | 6.25% Notes [Member]
Debt Instrument [Line Items]
Interest expense	16	16	16
Notes Payable, Other Payables [Member] | AGMH [Member] | Notes Payable 5.60 Percent [Member]
Debt Instrument [Line Items]
Interest expense	6	6	6
Notes Payable, Other Payables [Member] | AGM [Member]
Debt Instrument [Line Items]
Interest expense	$2	$5	$7

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	3 Months Ended																12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Basic EPS:
Net income (loss)	$532		$355		$159		$42		$349		$384		$219		($144)		$1,088		$808		$110
Less: Distributed and undistributed income (loss) available to nonvested shareholders																	0		1		0
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, basic																	1,088		807		110
Basic shares																	172.6		186.6		189.2
Basic EPS (in dollars per share)	$3.30	[1]	$2.10	[1]	$0.89	[1]	$0.23	[1]	$1.91	[1]	$2.10	[1]	$1.17	[1]	($0.74)	[1]	$6.30	[1]	$4.32	[1]	$0.58
Diluted EPS:
Plus: Re-allocation of undistributed income (loss) available to nonvested shareholders of AGL and subsidiaries																	0		0		0
Distributed and undistributed income (loss) available to common shareholders of AGL and subsidiaries, diluted																	$1,088		$807		$110
Basic shares																	172.6		186.6		189.2
Effect of dilutive securities:
Options and restricted stock awards (in shares)																	1		1		0.8
Equity units (in shares)																	0		0		0.7
Diluted shares																	173.6		187.6		190.7
Diluted EPS (in dollars per share)	$3.28	[1]	$2.09	[1]	$0.89	[1]	$0.23	[1]	$1.90	[1]	$2.09	[1]	$1.16	[1]	($0.74)	[1]	$6.26	[1]	$4.30	[1]	$0.57
Potentially dilutive securities excluded from computation of EPS because of antidilutive effect																	1.6		2.7		9.9
[1]	Per share amounts for the quarters and the full years have each been calculated separately. Accordingly, quarterly amounts may not sum up to the annual amounts because of differences in the average common shares outstanding during each period and, with regard to diluted per share amounts only, because of the inclusion of the effect of potentially dilutive securities only in the periods in which such effect would have been dilutive.

Shareholders_Equity_Share_Issu

Shareholders' Equity - Share Issuance (Details) (USD $)	0 Months Ended		12 Months Ended
	Jun. 01, 2012		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
			vote
Class of Stock [Line Items]
Authorized share capital			$5,000,000
Common stock, shares authorized			500,000,000	500,000,000
Common stock par value (per share)			$0.01	$0.01
Number of votes per share of common stock			1
Percentage of controlled shares			9.50%
Price per share of stock issued (in dollars per share)	$12.85	[1]
Proceeds from issuances of common stock	173,000,000	[1]	0	0	173,000,000
Proceeds from issuance of common stock, net proceeds	$173,000,000	[1]
Percentage of voting power held by one shareholder			75.00%
Assured Guaranty LTD [Member]
Class of Stock [Line Items]
Common stock issuance, net (in shares)	13,428,770	[1]
[1]	Relates to the settlement of forward purchase contracts. See Note 17, Long-Term Debt and Credit Facilities.

Shareholders_Equity_Shares_Rep

Shareholders' Equity - Shares Repurchased (Details) (USD $)	12 Months Ended			2 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 26, 2015
Equity, Class of Treasury Stock [Line Items]
Repurchases of common stock	($590,000,000)	($264,000,000)	($24,000,000)
Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Authorized repurchase amount	210,000,000
Shares repurchased	24,413,781	12,512,759	2,066,759
Repurchases of common stock	-590,000,000	-264,000,000	-24,000,000
Average price paid (in dollars per share)	$24.17	$21.12	$11.76
Affiliated Entity [Member] | Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Authorized repurchase amount		5,000,000
Repurchases of common stock		-109,700,000
Subsequent Event [Member] | Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Shares repurchased				3,581,767
Repurchases of common stock				($92,000,000)
Average price paid (in dollars per share)				$25.63

Shareholders_Equity_Deferred_C

Shareholders' Equity - Deferred Compensation (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
	Unit	Unit
Defined Benefit Plan Disclosure [Line Items]
Deferred equity compensation, shares	320,193	320,193
AGC [Member] | Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of AGL common shares represented by each unit in employer stock fund	1
Number of units in AGC SERP (in units)	74,309	74,309
Chief Executive Officer and General Counsel [Member] | Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of AGL common shares represented by each unit in employer stock fund	1
Deferred equity compensation, shares	320,193	320,193

Shareholders_Equity_Dividends_

Shareholders' Equity - Dividends (Details) (USD $)

0 Months Ended

3 Months Ended

12 Months Ended

0 Months Ended

Feb. 05, 2014

Feb. 07, 2013

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Feb. 04, 2015

Class of Stock [Line Items]

Dividends (in dollars per share)

$0.11

[1]

$0.11

[1]

$0.11

[1]

$0.11

[1]

$0.10

[1]

$0.10

[1]

$0.10

[1]

$0.10

[1]

$0.09

$0.44

[1]

$0.40

[1]

$0.36

Increase in common stock dividend (as a percent)

10.00%

11.00%

Subsequent Event [Member]

Class of Stock [Line Items]

Dividends (in dollars per share)

$0.12

Increase in common stock dividend (as a percent)

9.00%

[1]

Per share amounts for the quarters and the full years have each been calculated separately. Accordingly, quarterly amounts may not sum up to the annual amounts because of differences in the average common shares outstanding during each period and, with regard to diluted per share amounts only, because of the inclusion of the effect of potentially dilutive securities only in the periods in which such effect would have been dilutive.

Employee_Benefit_Plans_Awards_

Employee Benefit Plans - Awards Activity (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Options [Member]
Summary of options issued and outstanding
Balance at the beginning of the period (in shares)	3,129,251
Options granted (in shares)	83,162
Options exercised (in shares)	-409,560
Options forfeited/expired (in shares)	0
Balance at the end of the period (in shares)	2,802,853	3,129,251
Weighted Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$20.97
Options granted (in dollars per share)	$21.88
Options exercised (in dollars per share)	$17.88
Options forfeited (in dollars per share)	$0
Balance at the end of the period (in dollars per share)	$21.45	$20.97
Weighted Average Grant Date Fair Value (in dollars per share)	$10.35	$8.94	$8.62
Number of Exercisable Options (in shares)	2,631,653	2,987,088
Performance Stock Options [Member]
Summary of options issued and outstanding
Balance at the beginning of the period (in shares)	365,717
Options granted (in shares)	0
Options exercised (in shares)	0
Options forfeited/expired (in shares)	-118,838
Balance at the end of the period (in shares)	246,879	365,717
Weighted Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$17.80
Options granted (in dollars per share)	$0
Options exercised (in dollars per share)	$0
Options forfeited (in dollars per share)	$17.44
Balance at the end of the period (in dollars per share)	$17.97	$17.80
Weighted Average Grant Date Fair Value (in dollars per share)	$0	$8.17	$7.84
Number of Exercisable Options (in shares)	0	0
Restricted Stock Awards [Member]
Restricted Stock Award and Restricted Stock Unit Activity
Nonvested at the beginning of the period (in shares)	48,273
Granted (in shares)	47,747
Vested (in shares)	-48,273
Forfeited (in shares)	-4,170
Nonvested at the end of the period (in shares)	43,577
Weighted Average Grant-Date Fair Value
Nonvested at the beginning of the period (in dollars per share)	$23.20
Granted (in dollars per share)	$23.98
Vested (in dollars per share)	$23.20
Forfeited (in dollars per share)	$23.98
Nonvested at the end of the period (in dollars per share)	$23.98
Restricted Stock Units [Member]
Restricted Stock Award and Restricted Stock Unit Activity
Nonvested at the beginning of the period (in shares)	736,409
Granted (in shares)	238,976
Vested (in shares)	-284,082
Forfeited (in shares)	0
Nonvested at the end of the period (in shares)	691,303
Weighted Average Grant-Date Fair Value
Nonvested at the beginning of the period (in dollars per share)	$17.63
Granted (in dollars per share)	$21.61
Vested (in dollars per share)	$17.13
Forfeited (in dollars per share)	$0
Nonvested at the end of the period (in dollars per share)	$19.23
Performance Restricted Stock Units [Member]
Restricted Stock Award and Restricted Stock Unit Activity
Nonvested at the beginning of the period (in shares)	223,410
Granted (in shares)	203,287
Vested (in shares)	0
Forfeited (in shares)	-3,395
Nonvested at the end of the period (in shares)	423,302
Weighted Average Grant-Date Fair Value
Nonvested at the beginning of the period (in dollars per share)	$27.79
Granted (in dollars per share)	$25.17
Vested (in dollars per share)	$0
Forfeited (in dollars per share)	$27.35
Nonvested at the end of the period (in dollars per share)	$26.72

Employee_Benefit_Plans_Weighte

Employee Benefit Plans - Weighted Average Assumptions on Option Pricing (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Performance Stock Options [Member]
Employee benefit plans [Line Items]
Dividend yield (as a percent)		2.07%	2.06%
Expected volatility (as a percent)		53.50%	58.89%
Risk free interest rate (as a percent)		1.36%	1.45%
Expected life (in years)		6 years 3 months 18 days	6 years 3 months 18 days
Forfeiture rate (as a percent)		4.50%	4.50%
Weighted average grant date fair value (in dollars per share)	$0	$8.17	$7.84
Stock Options [Member]
Employee benefit plans [Line Items]
Dividend yield (as a percent)	2.03%	2.07%	2.06%
Expected volatility (as a percent)	53.24%	53.41%	58.89%
Risk free interest rate (as a percent)	2.21%	1.35%	1.45%
Expected life (in years)	6 years 7 months 6 days	6 years 7 months 6 days	6 years 7 months 6 days
Forfeiture rate (as a percent)	3.50%	4.50%	4.50%
Weighted average grant date fair value (in dollars per share)	$10.35	$8.94	$8.62

Employee_Benefit_Plans_Stock_P

Employee Benefit Plans - Stock Purchase Plan (Details) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee benefit plans [Line Items]
Recorded in share-based compensation, after the effects of DAC	$9	$7	$7
Employee Stock [Member] | Employee Stock Purchase Plan [Member]
Employee benefit plans [Line Items]
Proceeds from purchase of shares by employees	0.9	0.9	0.6
Number of shares issued by the Company	43,273	57,980	54,612
Recorded in share-based compensation, after the effects of DAC	$0.20	$0.30	$0.20

Employee_Benefit_Plans_ShareBa

Employee Benefit Plans - Share-Based Compensation Expense (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-Based Compensation Expense
Recurring amortization	$9	$7	$6
Accelerated amortization for retirement eligible employees	0	0	1
Recorded in share-based compensation, after the effects of DAC	9	7	7
Employee Stock Purchase Plan Expense	0	0	0
Total Share‑Based Cost	10	8	8
Less: Share‑based compensation capitalized as DAC	0	0	1
Share‑based compensation expense	10	8	7
Income tax benefit	2	2	2
Employee [Member]
Share-Based Compensation Expense
Total Share‑Based Cost	9	7	7
Directors [Member}
Share-Based Compensation Expense
Total Share‑Based Cost	$1	$1	$1

Employee_Benefit_Plans_Narrati

Employee Benefit Plans - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee benefit plans [Line Items]
Recognized contribution expense	$11,000,000	$10,000,000	$9,000,000
Stock Options [Member]
Employee benefit plans [Line Items]
Aggregate intrinsic value of awards outstanding	13,000,000
Weighted average remaining contractual term of awards outstanding (in years)	2 years 11 months
Aggregate intrinsic value of exercisable awards	12,000,000
Weighted average remaining contractual term of exercisable awards (in years)	2 years 8 months
Unrecognized compensation expense	1,000,000
Expected weighted-average remaining service period for recognition of unrecognized compensation cost (in years)	1 year 3 months 18 days
Expected volatility, inputs, average historical share price volatility and implied volatilities of certain at-the-money actively traded call options	7 years
Risk free interest rate, inputs, implied U.S. Treasury yield currently available, term	7 years
Total intrinsic value of awards exercised	3,000,000	7,500,000	100,000
Amount received from exercise of awards	4,300,000	2,600,000	44,000
Stock Options [Member] | Employee [Member]
Employee benefit plans [Line Items]
Vesting period of awards (in years)	3 years
Stock Options [Member] | Employee [Member] | Minimum [Member]
Employee benefit plans [Line Items]
Years from grant date until expiration	7 years
Stock Options [Member] | Employee [Member] | Maximum [Member]
Employee benefit plans [Line Items]
Years from grant date until expiration	10 years
Stock Options [Member] | Directors [Member}
Employee benefit plans [Line Items]
Vesting period of awards (in years)	1 year
Stock Options [Member] | Directors [Member} | Minimum [Member]
Employee benefit plans [Line Items]
Years from grant date until expiration	7 years
Stock Options [Member] | Directors [Member} | Maximum [Member]
Employee benefit plans [Line Items]
Years from grant date until expiration	10 years
Performance Stock Options [Member]
Employee benefit plans [Line Items]
Years from grant date until expiration	7 years
Aggregate intrinsic value of awards outstanding	2,000,000
Weighted average remaining contractual term of awards outstanding (in years)	4 years 5 months
Expected weighted-average remaining service period for recognition of unrecognized compensation cost (in years)	0 years 10 months 24 days
Expected volatility, inputs, average historical share price volatility and implied volatilities of certain at-the-money actively traded call options	7 years
Risk free interest rate, inputs, implied U.S. Treasury yield currently available, term	7 years
Unrecognized compensation expense	300,000
Restricted Stock Awards [Member]
Employee benefit plans [Line Items]
Expected weighted-average remaining service period for recognition of unrecognized compensation cost (in years)	0 years 4 months 24 days
Unrecognized compensation expense	400,000
Total fair value of awards vested	1,000,000	1,000,000	1,000,000
Restricted Stock Awards [Member] | Employee [Member]
Employee benefit plans [Line Items]
Vesting period of awards (in years)	4 years
Restricted Stock Awards [Member] | Directors [Member}
Employee benefit plans [Line Items]
Vesting period of awards (in years)	1 year
Restricted Stock Units [Member]
Employee benefit plans [Line Items]
Expected weighted-average remaining service period for recognition of unrecognized compensation cost (in years)	1 year 10 months 24 days
Unrecognized compensation expense	5,200,000
Total fair value of awards delivered	5,000,000	5,000,000	6,000,000
Performance Restricted Stock Units [Member]
Employee benefit plans [Line Items]
Expected weighted-average remaining service period for recognition of unrecognized compensation cost (in years)	1 year 10 months 24 days
Unrecognized compensation expense	3,700,000
Employee Stock Purchase Plan [Member] | Employee Stock [Member]
Employee benefit plans [Line Items]
Value of shares that can be purchased as a percentage of participant's compensation	10.00%
Value of shares that can be purchased	25,000
Capital shares reserved for future issuance	600,000
Purchase price of shares as a percentage of the fair market value of the stock	85.00%
Assured Guaranty Ltd. 2004 Long-Term Incentive Plan [Member]
Employee benefit plans [Line Items]
Maximum number of common shares that may be delivered	18,670,000
Assured Guaranty Ltd. 2004 Long-Term Incentive Plan [Member] | Stock Options [Member]
Employee benefit plans [Line Items]
Number of common shares available for grant	10,712,661
Share-based Compensation Award, Tranche One [Member]
Employee benefit plans [Line Items]
Vesting percentage			35.00%
Share-based Compensation Award, Tranche One [Member] | Performance Stock Options [Member]
Employee benefit plans [Line Items]
Vesting percentage	35.00%
Share-based Compensation Award, Tranche Two [Member] | Performance Stock Options [Member]
Employee benefit plans [Line Items]
Vesting percentage	50.00%
Share-based Compensation Award, Tranche Two [Member] | Performance Restricted Stock Units [Member]
Employee benefit plans [Line Items]
Vesting percentage			100.00%
Share-based Compensation Award, Tranche Three [Member] | Performance Stock Options [Member]
Employee benefit plans [Line Items]
Vesting percentage	100.00%
Share-based Compensation Award, Tranche Three [Member] | Performance Restricted Stock Units [Member]
Employee benefit plans [Line Items]
Vesting percentage			200.00%
United States [Member] | Pension Plan [Member]
Employee benefit plans [Line Items]
Core contribution made by the company as a percentage of participant's compensation	6.00%
Number of years of service to become fully vested	1 year
United States [Member] | 401 (k) Plan [Member] | Pension Plan [Member]
Employee benefit plans [Line Items]
Maximum amount that can be contributed by eligible participants	17,500
Percentage by which employer contribution matches up to 6% of participant's compensation	100.00%
Maximum percentage of participant's compensation eligible for employer contribution match	6.00%
Performance Retention Plan [Member]
Employee benefit plans [Line Items]
Defined contribution expenses	$15,000,000	$17,000,000	$13,000,000
Number of installments for award vesting	3
Percentage of awards allocated to a performance period that includes the year of the award and the next year	25.00%
Percentage of awards allocated to a performance period that includes the year of the award and the next two years	25.00%
Percentage of awards allocated to a performance period that includes the year of the award and the next three years	50.00%

Other_Comprehensive_Income_Cha

Other Comprehensive Income - Changes in AOCI by Component (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period				$160				$515	$160	$515	$368
Other comprehensive income (loss) before reclassifications									169	-341
Amounts reclassified from AOCI to:
Net realized investment gains (losses)	-35	-19	-8	2	29	-7	2	28	-60	52	1
Interest expense	-25	-27	-20	-20	-19	-21	-21	-21	-92	-82	-92
Total (provision) benefit for income taxes	-224	-133	-59	-27	-140	-152	-110	68	-443	-334	-22
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(21), $5 and $(7)									41	-14	4
Other comprehensive income (loss)									210	-355	147
Net current period other comprehensive income (loss)									210	-355
Balance at end of period	370				160				370	160	515
Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)									62	-19
Interest expense									0	-1
Total before tax									62	-20
Total (provision) benefit for income taxes									-21	6
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(21), $5 and $(7)									41	-14
Net Unrealized Gains (Losses) on Investments with no Other-Than-Temporary Impairment [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period				178				517	178	517	365
Other comprehensive income (loss) before reclassifications									196	-309
Amounts reclassified from AOCI to:
Other comprehensive income (loss)											152
Net current period other comprehensive income (loss)									189	-339
Balance at end of period	367				178				367	178	517
Net Unrealized Gains (Losses) on Investments with no Other-Than-Temporary Impairment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)									-12	-43
Interest expense									0	0
Total before tax									-12	-43
Total (provision) benefit for income taxes									5	13
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(21), $5 and $(7)									-7	-30
Net Unrealized Gains (Losses) on Investments with Other-Than-Temporary Impairment [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period				-24				-5	-24	-5	2
Other comprehensive income (loss) before reclassifications									-20	-35
Amounts reclassified from AOCI to:
Other comprehensive income (loss)											-7
Net current period other comprehensive income (loss)									28	-19
Balance at end of period	4				-24				4	-24	-5
Net Unrealized Gains (Losses) on Investments with Other-Than-Temporary Impairment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)									74	24
Interest expense									0	0
Total before tax									74	24
Total (provision) benefit for income taxes									-26	-8
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(21), $5 and $(7)									48	16
Accumulated Translation Adjustment [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period				-3				-6	-3	-6	-8
Other comprehensive income (loss) before reclassifications									-7	3
Amounts reclassified from AOCI to:
Other comprehensive income (loss)											2
Net current period other comprehensive income (loss)									-7	3
Balance at end of period	-10				-3				-10	-3	-6
Accumulated Translation Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)									0	0
Interest expense									0	0
Total before tax									0	0
Total (provision) benefit for income taxes									0	0
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(21), $5 and $(7)									0	0
Cash Flow Hedge [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period				9				9	9	9	9
Other comprehensive income (loss) before reclassifications									0	0
Amounts reclassified from AOCI to:
Other comprehensive income (loss)											0
Net current period other comprehensive income (loss)									0	0
Balance at end of period	9				9				9	9	9
Cash Flow Hedge [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Amounts reclassified from AOCI to:
Net realized investment gains (losses)									0	0
Interest expense									0	-1
Total before tax									0	-1
Total (provision) benefit for income taxes									0	1
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(21), $5 and $(7)									$0	$0

Subsidiary_Information_Condens

Subsidiary Information - Condensed Consolidating Balance Sheet (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Millions, unless otherwise specified
Assets
Total investment portfolio and cash	$11,459	$10,969
Investment in subsidiaries	0	0
Premiums receivable, net of commissions payable	729	876
Ceded unearned premium reserve	381	452
Deferred acquisition costs	121	124	116	132
Reinsurance recoverable on unpaid losses	78	36
Credit derivative assets	68	94
Deferred tax asset, net	260	688
Intercompany receivable	0	0
Financial guaranty variable interest entities’ assets, at fair value	1,402	2,565
Other	427	483
Total assets	14,925	16,287
Liabilities and shareholders’ equity
Unearned premium reserve	4,261	4,595
Loss and loss adjustment expense reserve	799	592
Long-term debt	1,303	816
Intercompany payable	0	0
Credit derivative liabilities	963	1,787
Deferred tax liabilities, net	0	0
Financial guaranty variable interest entities’ liabilities, at fair value	1,419	2,871
Other	422	511
Total liabilities	9,167	11,172
Effect on shareholders’ equity (decrease) increase	5,758	5,115	4,994	4,652
Noncontrolling interest	0	0
Total shareholders' equity	5,758	5,115
Total liabilities and shareholders’ equity	14,925	16,287
Reportable Legal Entities [Member] | Assured Guaranty Ltd. (Parent) [Member]
Assets
Total investment portfolio and cash	126	33
Investment in subsidiaries	5,612	5,066
Premiums receivable, net of commissions payable	0	0
Ceded unearned premium reserve	0	0
Deferred acquisition costs	0	0
Reinsurance recoverable on unpaid losses	0	0
Credit derivative assets	0	0
Deferred tax asset, net	0	0
Intercompany receivable	0	0
Financial guaranty variable interest entities’ assets, at fair value	0	0
Other	27	23
Total assets	5,765	5,122
Liabilities and shareholders’ equity
Unearned premium reserve	0	0
Loss and loss adjustment expense reserve	0	0
Long-term debt	0	0
Intercompany payable	0	0
Credit derivative liabilities	0	0
Deferred tax liabilities, net	0	0
Financial guaranty variable interest entities’ liabilities, at fair value	0	0
Other	7	7
Total liabilities	7	7
Effect on shareholders’ equity (decrease) increase	5,758	5,115
Noncontrolling interest	0	0
Total shareholders' equity	5,758	5,115
Total liabilities and shareholders’ equity	5,765	5,122
Reportable Legal Entities [Member] | AGUS (Issuer) [Member]
Assets
Total investment portfolio and cash	204	186
Investment in subsidiaries	5,072	4,191
Premiums receivable, net of commissions payable	0	0
Ceded unearned premium reserve	0	0
Deferred acquisition costs	0	0
Reinsurance recoverable on unpaid losses	0	0
Credit derivative assets	0	0
Deferred tax asset, net	54	97
Intercompany receivable	0	0
Financial guaranty variable interest entities’ assets, at fair value	0	0
Other	77	17
Total assets	5,407	4,491
Liabilities and shareholders’ equity
Unearned premium reserve	0	0
Loss and loss adjustment expense reserve	0	0
Long-term debt	847	348
Intercompany payable	90	90
Credit derivative liabilities	0	0
Deferred tax liabilities, net	0	0
Financial guaranty variable interest entities’ liabilities, at fair value	0	0
Other	9	7
Total liabilities	946	445
Effect on shareholders’ equity (decrease) increase	4,461	4,046
Noncontrolling interest	0	0
Total shareholders' equity	4,461	4,046
Total liabilities and shareholders’ equity	5,407	4,491
Reportable Legal Entities [Member] | AGMH (Issuer) [Member]
Assets
Total investment portfolio and cash	47	42
Investment in subsidiaries	3,965	3,574
Premiums receivable, net of commissions payable	0	0
Ceded unearned premium reserve	0	0
Deferred acquisition costs	0	0
Reinsurance recoverable on unpaid losses	0	0
Credit derivative assets	0	0
Deferred tax asset, net	0	0
Intercompany receivable	0	0
Financial guaranty variable interest entities’ assets, at fair value	0	0
Other	27	31
Total assets	4,039	3,647
Liabilities and shareholders’ equity
Unearned premium reserve	0	0
Loss and loss adjustment expense reserve	0	0
Long-term debt	437	430
Intercompany payable	0	0
Credit derivative liabilities	0	0
Deferred tax liabilities, net	94	95
Financial guaranty variable interest entities’ liabilities, at fair value	0	0
Other	16	16
Total liabilities	547	541
Effect on shareholders’ equity (decrease) increase	3,492	3,106
Noncontrolling interest	0	0
Total shareholders' equity	3,492	3,106
Total liabilities and shareholders’ equity	4,039	3,647
Reportable Legal Entities [Member] | Other Entities [Member]
Assets
Total investment portfolio and cash	11,382	11,008
Investment in subsidiaries	339	289
Premiums receivable, net of commissions payable	864	1,025
Ceded unearned premium reserve	1,469	1,598
Deferred acquisition costs	186	198
Reinsurance recoverable on unpaid losses	338	170
Credit derivative assets	277	482
Deferred tax asset, net	295	681
Intercompany receivable	90	90
Financial guaranty variable interest entities’ assets, at fair value	1,402	2,565
Other	538	638
Total assets	17,180	18,744
Liabilities and shareholders’ equity
Unearned premium reserve	5,328	5,720
Loss and loss adjustment expense reserve	1,066	733
Long-term debt	19	38
Intercompany payable	300	300
Credit derivative liabilities	1,172	2,175
Deferred tax liabilities, net	0	0
Financial guaranty variable interest entities’ liabilities, at fair value	1,419	2,871
Other	764	853
Total liabilities	10,068	12,690
Effect on shareholders’ equity (decrease) increase	6,773	5,765
Noncontrolling interest	339	289
Total shareholders' equity	7,112	6,054
Total liabilities and shareholders’ equity	17,180	18,744
Consolidating Adjustments [Member]
Assets
Total investment portfolio and cash	-300	-300
Investment in subsidiaries	-14,988	-13,120
Premiums receivable, net of commissions payable	-135	-149
Ceded unearned premium reserve	-1,088	-1,146
Deferred acquisition costs	-65	-74
Reinsurance recoverable on unpaid losses	-260	-134
Credit derivative assets	-209	-388
Deferred tax asset, net	-89	-90
Intercompany receivable	-90	-90
Financial guaranty variable interest entities’ assets, at fair value	0	0
Other	-242	-226
Total assets	-17,466	-15,717
Liabilities and shareholders’ equity
Unearned premium reserve	-1,067	-1,125
Loss and loss adjustment expense reserve	-267	-141
Long-term debt	0	0
Intercompany payable	-390	-390
Credit derivative liabilities	-209	-388
Deferred tax liabilities, net	-94	-95
Financial guaranty variable interest entities’ liabilities, at fair value	0	0
Other	-374	-372
Total liabilities	-2,401	-2,511
Effect on shareholders’ equity (decrease) increase	-14,726	-12,917
Noncontrolling interest	-339	-289
Total shareholders' equity	-15,065	-13,206
Total liabilities and shareholders’ equity	($17,466)	($15,717)

Subsidiary_Information_Condens1

Subsidiary Information - Condensed Consolidating Statement of Operations (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenues
Net earned premiums	$158	$144	$136	$132	$182	$159	$163	$248	$570		$752		$853
Net investment income	102	102	96	103	107	99	93	94	403		393		404
Net realized investment gains (losses)	-35	-19	-8	2	29	-7	2	28	-60		52		1
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements									23		-42		-108
Net unrealized gains (losses)									800	[1]	107	[1]	-477	[1]
Net change in fair value of credit derivatives	676	255	103	-211	229	354	74	-592	823		65		-585
Other									258		346		281
Total revenues									1,994		1,608		954
Expenses
Loss and LAE	72	-44	57	41	85	55	62	-48	126		154		504
Amortization of DAC	13	4	3	5	4	4	1	3	25		12		14
Interest expense	25	27	20	20	19	21	21	21	92		82		92
Other operating expenses	55	50	55	60	52	54	52	60	220		218		212
Total expenses									463		466		822
Income (loss) before income taxes	756	488	218	69	489	536	329	-212	1,531		1,142		132
Total (provision) benefit for income taxes	-224	-133	-59	-27	-140	-152	-110	68	-443		-334		-22
Equity in net earnings of subsidiaries									0		0		0
Net income (loss)									1,088		808		110
Less: noncontrolling interest									0		0
Net income (loss)	532	355	159	42	349	384	219	-144	1,088		808		110
Comprehensive income (loss)									1,298		453		257
Reportable Legal Entities [Member] | Assured Guaranty Ltd. (Parent) [Member]
Revenues
Net earned premiums									0		0		0
Net investment income									0		0		0
Net realized investment gains (losses)									0		0		0
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements									0		0		0
Net unrealized gains (losses)									0		0		0
Net change in fair value of credit derivatives									0		0		0
Other									0		0		0
Total revenues									0		0		0
Expenses
Loss and LAE									0		0		0
Amortization of DAC									0		0		0
Interest expense									0		0		0
Other operating expenses									31		22		21
Total expenses									31		22		21
Income (loss) before income taxes									-31		-22		-21
Total (provision) benefit for income taxes									0		0		0
Equity in net earnings of subsidiaries									1,119		830		131
Net income (loss)									1,088		808		110
Less: noncontrolling interest									0		0
Net income (loss)									1,088		808
Comprehensive income (loss)									1,298		453		257
Reportable Legal Entities [Member] | AGUS (Issuer) [Member]
Revenues
Net earned premiums									0		0		0
Net investment income									0		0		0
Net realized investment gains (losses)									0		0		0
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements									0		0		0
Net unrealized gains (losses)									0		0		0
Net change in fair value of credit derivatives									0		0		0
Other									0		0		0
Total revenues									0		0		0
Expenses
Loss and LAE									0		0		0
Amortization of DAC									0		0		0
Interest expense									40		28		35
Other operating expenses									1		1		2
Total expenses									41		29		37
Income (loss) before income taxes									-41		-29		-37
Total (provision) benefit for income taxes									14		9		13
Equity in net earnings of subsidiaries									983		768		177
Net income (loss)									956		748		153
Less: noncontrolling interest									0		0
Net income (loss)									956		748
Comprehensive income (loss)									1,114		522		266
Reportable Legal Entities [Member] | AGMH (Issuer) [Member]
Revenues
Net earned premiums									0		0		0
Net investment income									1		1		1
Net realized investment gains (losses)									0		0		0
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements									0		0		0
Net unrealized gains (losses)									0		0		0
Net change in fair value of credit derivatives									0		0		0
Other									0		0		0
Total revenues									1		1		1
Expenses
Loss and LAE									0		0		0
Amortization of DAC									0		0		0
Interest expense									54		54		54
Other operating expenses									1		1		1
Total expenses									55		55		55
Income (loss) before income taxes									-54		-54		-54
Total (provision) benefit for income taxes									19		17		19
Equity in net earnings of subsidiaries									513		701		424
Net income (loss)									478		664		389
Less: noncontrolling interest									0		0
Net income (loss)									478		664
Comprehensive income (loss)									577		515		465
Reportable Legal Entities [Member] | Other Entities [Member]
Revenues
Net earned premiums									566		740		833
Net investment income									412		408		422
Net realized investment gains (losses)									-58		87		1
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements									23		-42		-108
Net unrealized gains (losses)									800		107		-477
Net change in fair value of credit derivatives									823		65		-585
Other									259		348		284
Total revenues									2,002		1,648		955
Expenses
Loss and LAE									122		144		509
Amortization of DAC									33		12		28
Interest expense									16		20		22
Other operating expenses									195		199		194
Total expenses									366		375		753
Income (loss) before income taxes									1,636		1,273		202
Total (provision) benefit for income taxes									-469		-387		-38
Equity in net earnings of subsidiaries									32		19		153
Net income (loss)									1,199		905		317
Less: noncontrolling interest									32		19
Net income (loss)									1,167		886
Comprehensive income (loss)									1,570		309		577
Consolidating Adjustments [Member]
Revenues
Net earned premiums									4		12		20
Net investment income									-10		-16		-19
Net realized investment gains (losses)									-2		-35		0
Net change in fair value of credit derivatives:
Realized gains (losses) and other settlements									0		0		0
Net unrealized gains (losses)									0		0		0
Net change in fair value of credit derivatives									0		0		0
Other									-1		-2		-3
Total revenues									-9		-41		-2
Expenses
Loss and LAE									4		10		-5
Amortization of DAC									-8		0		-14
Interest expense									-18		-20		-19
Other operating expenses									-8		-5		-6
Total expenses									-30		-15		-44
Income (loss) before income taxes									21		-26		42
Total (provision) benefit for income taxes									-7		27		-16
Equity in net earnings of subsidiaries									-2,647		-2,318		-885
Net income (loss)									-2,633		-2,317		-859
Less: noncontrolling interest									-32		-19
Net income (loss)									-2,601		-2,298
Comprehensive income (loss)									($3,261)		($1,346)		($1,308)
[1]	Except for net estimated credit impairments (i.e., net expected loss to be paid as discussed in Note 6), the unrealized gains and losses on credit derivatives are expected to reduce to zero as the exposure approaches its maturity date. With considerable volatility continuing in the market, unrealized gains (losses) on credit derivatives may fluctuate significantly in future periods.

Subsidiary_Information_Condens2

Subsidiary Information - Condensed Consolidating Statement of Cash Flows (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows provided by (used in) operating activities	$577	$244	($165)
Fixed-maturity securities:
Purchases	-2,801	-1,886	-1,649
Sales	1,251	1,029	912
Maturities	877	883	1,105
Sales (purchases) of short-term investments, net	158	-87	29
Net proceeds from financial guaranty variable entities’ assets	408	663	545
Acquisition of MAC	0	0	-91
Intercompany debt	0	0	0
Investment in subsidiary	0	0	0
Other	11	79	92
Net cash flows provided by (used in) investing activities	-96	681	943
Cash flows from financing activities
Issuance of common stock	0	0	173
Return of capital	0	0	0
Capital contribution from parent	0	0	0
Dividends paid	-76	-75	-69
Repurchases of common stock	-590	-264	-24
Share activity under option and incentive plans	1	-1	-3
Net paydowns of financial guaranty variable entities’ liabilities	-396	-511	-724
Net proceeds from issuance of long-term debt	495	0	0
Payment of long-term debt	-19	-27	-209
Intercompany debt	0	0	0
Net cash flows provided by (used in) financing activities	-585	-878	-856
Effect of foreign exchange rate changes	-5	-1	1
Increase (decrease) in cash	-109	46	-77
Cash at beginning of period	184	138	215
Cash at end of period	75	184	138
Reportable Legal Entities [Member] | Assured Guaranty Ltd. (Parent) [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows provided by (used in) operating activities	758	128	138
Fixed-maturity securities:
Purchases	0	0	-211
Sales	0	176	0
Maturities	0	29	3
Sales (purchases) of short-term investments, net	-93	7	-7
Net proceeds from financial guaranty variable entities’ assets		0	0
Acquisition of MAC			0
Intercompany debt	0	0	0
Investment in subsidiary	0	0	0
Other	0	0	0
Net cash flows provided by (used in) investing activities	-93	212	-215
Cash flows from financing activities
Issuance of common stock			173
Return of capital	0	0	0
Capital contribution from parent	0	0	0
Dividends paid	-76	-75	-69
Repurchases of common stock	-590	-264	-24
Share activity under option and incentive plans	1	-1	-3
Net paydowns of financial guaranty variable entities’ liabilities	0	0	0
Net proceeds from issuance of long-term debt	0
Payment of long-term debt	0	0	0
Intercompany debt	0	0	0
Net cash flows provided by (used in) financing activities	-665	-340	77
Effect of foreign exchange rate changes	0	0	0
Increase (decrease) in cash	0	0	0
Cash at beginning of period	0	0	0
Cash at end of period	0	0	0
Reportable Legal Entities [Member] | AGUS (Issuer) [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows provided by (used in) operating activities	223	178	6
Fixed-maturity securities:
Purchases	-540	-93	-1
Sales	464	1	0
Maturities	6	3	0
Sales (purchases) of short-term investments, net	-15	-28	27
Net proceeds from financial guaranty variable entities’ assets		0	0
Acquisition of MAC			-91
Intercompany debt	0	0	0
Investment in subsidiary	0	0	0
Other	0	0	0
Net cash flows provided by (used in) investing activities	-85	-117	-65
Cash flows from financing activities
Issuance of common stock			0
Return of capital	0	0	0
Capital contribution from parent	0	0	0
Dividends paid	-700	0	0
Repurchases of common stock	0	0	0
Share activity under option and incentive plans	0	0	0
Net paydowns of financial guaranty variable entities’ liabilities	0	0	0
Net proceeds from issuance of long-term debt	495
Payment of long-term debt	0	0	-173
Intercompany debt	0	-7	173
Net cash flows provided by (used in) financing activities	-205	-7	0
Effect of foreign exchange rate changes	0	0	0
Increase (decrease) in cash	-67	54	-59
Cash at beginning of period	67	13	72
Cash at end of period	0	67	13
Reportable Legal Entities [Member] | AGMH (Issuer) [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows provided by (used in) operating activities	144	133	20
Fixed-maturity securities:
Purchases	-8	-26	-13
Sales	10	25	13
Maturities	1	2	6
Sales (purchases) of short-term investments, net	-3	-15	26
Net proceeds from financial guaranty variable entities’ assets		0	0
Acquisition of MAC			0
Intercompany debt	0	0	0
Investment in subsidiary	50	49	46
Other	0	0	0
Net cash flows provided by (used in) investing activities	50	35	78
Cash flows from financing activities
Issuance of common stock			0
Return of capital	0	0	0
Capital contribution from parent	0	0	0
Dividends paid	-190	-168	-98
Repurchases of common stock	0	0	0
Share activity under option and incentive plans	0	0	0
Net paydowns of financial guaranty variable entities’ liabilities	0	0	0
Net proceeds from issuance of long-term debt	0
Payment of long-term debt	0	0	0
Intercompany debt	0	0	0
Net cash flows provided by (used in) financing activities	-190	-168	-98
Effect of foreign exchange rate changes	0	0	0
Increase (decrease) in cash	4	0	0
Cash at beginning of period	0	0	0
Cash at end of period	4	0	0
Reportable Legal Entities [Member] | Other Entities [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows provided by (used in) operating activities	663	347	5
Fixed-maturity securities:
Purchases	-2,253	-1,832	-1,424
Sales	777	892	899
Maturities	870	849	1,096
Sales (purchases) of short-term investments, net	269	-51	-17
Net proceeds from financial guaranty variable entities’ assets	408	663	545
Acquisition of MAC			0
Intercompany debt	0	7	-173
Investment in subsidiary	0	0	0
Other	11	79	92
Net cash flows provided by (used in) investing activities	82	607	1,018
Cash flows from financing activities
Issuance of common stock			0
Return of capital	-50	-50	-50
Capital contribution from parent	0	1	4
Dividends paid	-321	-374	-236
Repurchases of common stock	0	0	0
Share activity under option and incentive plans	0	0	0
Net paydowns of financial guaranty variable entities’ liabilities	-396	-511	-724
Net proceeds from issuance of long-term debt	0
Payment of long-term debt	-19	-27	-36
Intercompany debt	0	0	0
Net cash flows provided by (used in) financing activities	-786	-961	-1,042
Effect of foreign exchange rate changes	-5	-1	1
Increase (decrease) in cash	-46	-8	-18
Cash at beginning of period	117	125	143
Cash at end of period	71	117	125
Consolidating Adjustments [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows provided by (used in) operating activities	-1,211	-542	-334
Fixed-maturity securities:
Purchases	0	65	0
Sales	0	-65	0
Maturities	0	0	0
Sales (purchases) of short-term investments, net	0	0	0
Net proceeds from financial guaranty variable entities’ assets	0	0	0
Acquisition of MAC			0
Intercompany debt	0	-7	173
Investment in subsidiary	-50	-49	-46
Other	0	0	0
Net cash flows provided by (used in) investing activities	-50	-56	127
Cash flows from financing activities
Issuance of common stock			0
Return of capital	50	50	50
Capital contribution from parent	0	-1	-4
Dividends paid	1,211	542	334
Repurchases of common stock	0	0	0
Share activity under option and incentive plans	0	0	0
Net paydowns of financial guaranty variable entities’ liabilities	0	0	0
Net proceeds from issuance of long-term debt	0
Payment of long-term debt	0	0	0
Intercompany debt	0	7	-173
Net cash flows provided by (used in) financing activities	1,261	598	207
Effect of foreign exchange rate changes	0	0	0
Increase (decrease) in cash	0	0	0
Cash at beginning of period	0	0	0
Cash at end of period	$0	$0	$0

Quarterly_Financial_Informatio2

Quarterly Financial Information (Unaudited) (Details) (USD $)	3 Months Ended																	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenues
Net earned premiums	$158		$144		$136		$132		$182		$159		$163		$248			$570		$752		$853
Net investment income	102		102		96		103		107		99		93		94			403		393		404
Net realized investment gains (losses)	-35		-19		-8		2		29		-7		2		28			-60		52		1
Net change in fair value of credit derivatives	676		255		103		-211		229		354		74		-592			823		65		-585
Fair value gains (losses) on CCS	0		4		-6		-9		14		9		-3		-10			-11		10		-18
Fair value gains (losses) on FG VIEs	23		50		25		157		93		40		143		70			255		346		191
Other income (loss)	-3		-11		7		21		-5		16		-7		-14			14		-10		108
Expenses
Loss and LAE	72		-44		57		41		85		55		62		-48			126		154		504
Amortization of DAC	13		4		3		5		4		4		1		3			25		12		14
Interest expense	25		27		20		20		19		21		21		21			92		82		92
Other operating expenses	55		50		55		60		52		54		52		60			220		218		212
Income (loss) before provision for income taxes	756		488		218		69		489		536		329		-212			1,531		1,142		132
Provision (benefit) for income taxes	224		133		59		27		140		152		110		-68			443		334		22
Net income (loss)	$532		$355		$159		$42		$349		$384		$219		($144)			$1,088		$808		$110
Earnings (loss) per share, Basic (in dollars per share)	$3.30	[1]	$2.10	[1]	$0.89	[1]	$0.23	[1]	$1.91	[1]	$2.10	[1]	$1.17	[1]	($0.74)	[1]		$6.30	[1]	$4.32	[1]	$0.58
Earnings (loss) per share, Diluted (in dollars per share)	$3.28	[1]	$2.09	[1]	$0.89	[1]	$0.23	[1]	$1.90	[1]	$2.09	[1]	$1.16	[1]	($0.74)	[1]		$6.26	[1]	$4.30	[1]	$0.57
Dividends (in dollars per share)	$0.11	[1]	$0.11	[1]	$0.11	[1]	$0.11	[1]	$0.10	[1]	$0.10	[1]	$0.10	[1]	$0.10	[1]	$0.09	$0.44	[1]	$0.40	[1]	$0.36
[1]	Per share amounts for the quarters and the full years have each been calculated separately. Accordingly, quarterly amounts may not sum up to the annual amounts because of differences in the average common shares outstanding during each period and, with regard to diluted per share amounts only, because of the inclusion of the effect of potentially dilutive securities only in the periods in which such effect would have been dilutive.