MBIA (MBI) 10-Q 10 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2021	May 03, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Central Index Key	0000814585
Current Fiscal Year End Date	--12-31
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Mar. 31, 2021
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Trading Symbol	MBI
Entity Registrant Name	MBIA INC
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		54,349,163
Title of 12(b) Security	Common Stock
Security Exchange Name	NYSE
Entity File Number	1-9583
Entity Tax Identification Number	06-1185706
Entity Address, Address Line One	1 Manhattanville Road, Suite 301
Entity Address, City or Town	Purchase
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10577
Entity Incorporation, State or Country Code	CT
City Area Code	914
Local Phone Number	273-4545

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Investments:
Cash and cash equivalents	$ 121	$ 167
Total assets	5,375	5,751
Liabilities:
Total liabilities	5,403	5,602
Commitments and contingencies (Refer to Note 13: Commitments and Contingencies)
Equity:
Preferred stock, par value $1 per share; authorized shares - 10,000,000; issued and outstanding - none	0	0
Common stock, par value $1 per share; authorized shares - 400,000,000; issued shares - 283,186,115 and 283,186,115	283	283
Additional paid-in capital	2,934	2,962
Retained earnings (deficit)	(119)	(13)
Accumulated other comprehensive income (loss), net of tax of $8 and $8	39	115
Treasury stock, at cost - 228,837,465 and 229,508,967 shares	(3,178)	(3,211)
Total shareholders' equity of MBIA Inc.	(41)	136
Preferred stock of subsidiary	13	13
Total equity	(28)	149
Total liabilities and equity	5,375	5,751
Non Variable Interest Entity [Member]
Investments:
Fixed-maturity securities held as available-for-sale, at fair value (amortized cost $2,135 and $2,078)	2,222	2,257
Investments carried at fair value	207	196
Investments pledged as collateral, at fair value (amortized cost - and $6)	0	1
Short-term investments, at fair value (amortized cost $623 and $281)	623	282
Total investments	3,052	2,736
Cash and cash equivalents	116	158
Premiums receivable (net of allowance for credit losses $5 and $5)	215	216
Deferred acquisition costs	48	50
Insurance loss recoverable	1,622	1,677
Other assets	94	84
Liabilities:
Unearned premium revenue	386	405
Loss and loss adjustment expense reserves	990	990
Long-term debt	2,258	2,229
Medium-term notes (includes financial instruments carried at fair value of $105 and $110)	698	710
Investment agreements	268	269
Derivative liabilities	126	215
Other liabilities	203	161
Variable Interest Entity Primary Beneficiary [Member]
Investments:
Investments carried at fair value	76	77
Other assets	23	20
Cash	5	9
Loans receivable at fair value	124	120
Loan repurchase commitments	0	604
Total assets	228	830
Liabilities:
Variable interest entity notes (includes financial instruments carried at fair value of $325 and $350)	451	623
Other liabilities	23
Total liabilities	$ 474	$ 623

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Preferred stock, par value	$ 1	$ 1
Preferred stock, authorized shares	10,000,000	10,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 1	$ 1
Common stock, authorized shares	400,000,000	400,000,000
Common stock, issued shares	283,186,115	283,186,115
Accumulated other comprehensive income (loss), taxes	$ 8	$ 8
Treasury stock, shares	228,837,465	229,508,967
Non Variable Interest Entity [Member]
Fixed-maturity securities held as available-for-sale, amortized cost	$ 2,135	$ 2,078
Investments pledged as collateral, amortized cost	0	6
Short-term investments, amortized cost	623	281
Premiums receivable (net of allowance for credit losses)	5	5
Medium-term notes, financial instruments carried at fair value	105	110
Variable Interest Entity Primary Beneficiary [Member]
Variable interest entity notes, financial instruments carried at fair value	$ 325	$ 350

Consolidated Statements Of Oper

Consolidated Statements Of Operations - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Premiums earned:
Net gains (losses) on financial instruments at fair value and foreign exchange		$ 51	$ (63)
Total revenues		72	(6)
Expenses:
Losses and loss adjustment		98	243
Interest		41	47
Total expenses		178	327
Income (loss) before income taxes		(106)	(333)
Provision (benefit) for income taxes		0	0
Net income (loss)		$ (106)	$ (333)
Net income (loss) per common share:
Basic		$ (2.16)	$ (4.62)
Diluted		$ (2.16)	$ (4.62)
Weighted average number of common shares outstanding:
Basic	[1]	49,258,110	72,089,016
Diluted	[1]	49,258,110	72,089,016
Non Variable Interest Entity [Member]
Premiums earned:
Scheduled premiums earned		$ 15	$ 16
Refunding premiums earned		5	4
Premiums earned (net of ceded premiums of $1 and $1)		20	20
Net investment income		15	23
Net gains (losses) on financial instruments at fair value and foreign exchange		51	(63)
Expenses:
Losses and loss adjustment		98	243
Amortization of deferred acquisition costs		2	2
Operating		26	18
Interest		41	47
Variable Interest Entity Primary Beneficiary [Member]
Premiums earned:
Net investment income		0	8
Net gains (losses) on financial instruments at fair value and foreign exchange		(14)	15
Other net realized gains (losses)		0	(9)
Expenses:
Operating		2	2
Interest		$ 9	$ 15
[1]	Includes 0.9 million of participating securities that met the service condition and were eligible to receive nonforfeitable dividends or dividend equivalents for each of the three months ended March 31, 2021 and 2020, respectively.

Consolidated Statements Of Op_2

Consolidated Statements Of Operations (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Financial Guarantee Insurance Segment [Member]
Ceded premiums earned	$ 1	$ 1

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statements of Comprehensive Income (Loss)
Net income (loss)	$ (106)	$ (333)
Available-for-sale securities with no credit losses:
Unrealized gains (losses) arising during the period	(87)	48
Reclassification adjustments for (gains) losses included in net income (loss)	(5)	(3)
Foreign currency translation:
Foreign currency translation gains (losses)	1	0
Instrument-specific credit risk of liabilities measured at fair value:
Unrealized gains (losses) arising during the period	(5)	46
Reclassification adjustments for (gains) losses included in net income (loss)	20	2
Total other comprehensive income (loss)	(76)	93
Comprehensive income (loss)	$ (182)	$ (240)

Consolidated Statements Of Chan

Consolidated Statements Of Changes In Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings (deficit) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total Shareholders' Equity Of MBIA Inc. [Member]	Preferred Stock [Member]
Total equity balance at Dec. 31, 2019			$ 2,999	$ 607	$ (2)	$ (3,061)	$ 826
Balance (in common stock shares) at Dec. 31, 2019		283,433,401
Balance (in treasury stock shares) at Dec. 31, 2019						(204,000,108)
Cumulative effect of prospective application of new accounting principle | ASU 2016-13 [Member]				(42)
Net income (loss)	$ (333)			(333)
Other comprehensive income (loss)	93				93
Treasury shares acquired under share repurchase program						$ (65)
Treasury shares acquired under share repurchase program (in shares)						(8,082,756)
Common shares issued (cancelled), net (in shares)		0
Other						$ 43
Others (in shares)						809,869
Period change			(38)				(342)
Total equity balance at Mar. 31, 2020	497	$ 283	2,961	232	91	$ (3,083)	484	$ 13
Balance (in common stock shares) at Mar. 31, 2020		283,433,401
Balance (in treasury stock shares) at Mar. 31, 2020						(211,272,995)
Balance (in preferred stock shares) at Mar. 31, 2020								1,315
Total equity balance at Dec. 31, 2020	$ 149		2,962	(13)	115	$ (3,211)	136
Balance (in common stock shares) at Dec. 31, 2020	283,186,115	283,186,115
Balance (in treasury stock shares) at Dec. 31, 2020	(229,508,967)					(229,508,967)
Cumulative effect of prospective application of new accounting principle | ASU 2016-13 [Member]				0
Net income (loss)	$ (106)			(106)
Other comprehensive income (loss)	(76)				(76)
Treasury shares acquired under share repurchase program						$ 0
Treasury shares acquired under share repurchase program (in shares)						0
Common shares issued (cancelled), net (in shares)		0
Other						$ 33
Others (in shares)						671,502
Period change			(28)				(177)
Total equity balance at Mar. 31, 2021	$ (28)	$ 283	$ 2,934	$ (119)	$ 39	$ (3,178)	$ (41)	$ 13
Balance (in common stock shares) at Mar. 31, 2021	283,186,115	283,186,115
Balance (in treasury stock shares) at Mar. 31, 2021	(228,837,465)					(228,837,465)
Balance (in preferred stock shares) at Mar. 31, 2021	0							1,315

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Premiums, fees and reimbursements received	$ 3	$ 3
Investment income received	21	37
Financial guarantee losses and loss adjustment expenses paid	(58)	(75)
Proceeds from recoveries and reinsurance	17	10
Proceeds from loan repurchase commitments	600	0
Operating and employee related expenses paid	(32)	(34)
Interest paid, net of interest converted to principal	(22)	(23)
Net cash provided (used) by operating activities	529	(82)
Cash flows from investing activities:
Purchases of available-for-sale investments	(299)	(242)
Sales of available-for-sale investments	178	279
Paydowns and maturities of available-for-sale investments	96	123
Purchases of investments at fair value	(62)	(33)
Sales, paydowns, maturities and other proceeds of investments at fair value	59	34
Sales, paydowns and maturities (purchases) of short-term investments, net	(342)	178
Sales, paydowns and maturities of held-to-maturity investments	0	315
Paydowns and maturities of loans receivable	5	3
(Payments) proceeds for derivative settlements	(53)	(3)
Collateral (to) from counterparties	0	(44)
Net cash provided (used) by investing activities	(418)	610
Cash flows from financing activities:
Proceeds from investment agreements	0	3
Principal paydowns of investment agreements	0	(12)
Principal paydowns of variable interest entity notes	(156)	(323)
Purchases of treasury stock	(1)	(62)
Net cash provided (used) by financing activities	(157)	(394)
Net increase (decrease) in cash and cash equivalents	(46)	134
Cash and cash equivalents - beginning of period	167	83
Cash and cash equivalents - end of period	121	217
Reconciliation of net income (loss) to net cash provided (used) by operating activities:
Net income (loss)	(106)	(333)
Change in:
Accrued investment income	23	0
Unearned premium revenue	(19)	(19)
Loss and loss adjustment expense reserves	1	84
Insurance loss recoverable	55	86
Loan repurchase commitments	604	0
Accrued interest payable	25	35
Accrued expenses	(33)	(19)
Net (gains) losses on financial instruments at fair value and foreign exchange	(41)	48
Other net realized (gains) losses	0	9
Other operating	20	27
Total adjustments to net income (loss)	635	251
Net cash provided (used) by operating activities	$ 529	$ (82)

Business Developments and Risks

Business Developments and Risks and Uncertainties	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Business Developments and Risks and Uncertainties	Note 1: Business Developments and Risks and Uncertainties Summary MBIA Inc., together with its consolidated subsidiaries, (collectively, “MBIA” or the “Company”) operates within the financial guarantee insurance industry. MBIA manages three operating segments: 1) United States (“U.S.”) public finance insurance; 2) corporate; and 3) international and structured finance insurance. The Company’s U.S. public finance insurance business is managed through National Public Finance Guarantee Corporation (“National”), the corporate segment is operated through MBIA Inc. and several of its subsidiaries, including its service company, MBIA Services Corporation (“MBIA Services”) and its international and structured finance insurance business is primarily operated through MBIA Insurance Corporation and its subsidiary (“MBIA Corp.”). Refer to “Note 10: Business Segments” for further information about the Company’s operating segments. Business Developments Puerto Rico On January 1, 2021, the Commonwealth of Puerto Rico and certain of its instrumentalities (“Puerto Rico”) defaulted on scheduled debt service for National insured bonds and National paid gross claim payments in the aggregate of $51 million. As of March 31, 2021, National had $2.9 billion of debt service outstanding related to Puerto Rico. Refer to the “Risks and Uncertainties” section below for additional information on the Company’s Puerto Rico exposures. PREPA RSA In September of 2019, National agreed to join the restructuring support agreement, as amended (“RSA”), with the Puerto Rico Electric Power Authority (“PREPA”), other monoline insurers, a group of uninsured PREPA bondholders, Puerto Rico, and the Financial Oversight and Management Board for Puerto Rico (the “Oversight Board”). The Rule 9019 hearing to approve the RSA has been delayed several times, and most recently was adjourned due to the outbreak of the novel coronavirus COVID-19 (“COVID-19”) GO PSA and HTA PSA On February 22, 2021, National agreed to join a plan support agreement, dated as of February 22, 2021 (the “GO PSA”), among the Oversight Board, certain holders of GO Bonds and PBA Bonds, Assured Guaranty Corp. and Assured Guaranty Municipal Corp, and Syncora Guarantee Inc. in connection with the GO and PBA Title III cases. The GO PSA provides that, among other things, National shall receive a pro rata share of allocable cash, newly issued General Obligation bonds, a contingent value instrument and certain fees. The GO PSA also permitted National to terminate its participation in the GO PSA on or prior to March 31, 2021, which date was extended ultimately to May 5, 2021. On April 12, 2021, National, Assured Guaranty Corp., Assured Guaranty Municipal Corp. and the Oversight Board reached an agreement in principle settli n On April 6, 2021, the Oversight Board filed a m o Credit Suisse In January of 2021, the Court overseeing MBIA Corp.’s litigation against Credit Suisse Securities (USA) LLC and DLJ Mortgage Capital, Inc. (collectively, “Credit Suisse”), involving the ineligibility of a majority of the loans in the HEMT 2007-2 million in damages. In February of 2021, the parties to the litigation entered into a settlement agreement pursuant to which Credit Suisse paid MBIA Corp. put-back MBIA Corp. Refinanced Facility During the three months ended March 31, 2021, MBIA Corp. prepaid $150 million of the MZ Funding LLC (“MZ Funding”) financing facility’s 12% senior notes maturing on January 20, 2022 (“Refinanced Facility”). As of March 31, 2021, the consolidated outstanding amount of the Refinanced Facility was $127 million is included in “Variable interest entity notes” under “Liabilities of consolidated variable interest entities” on the Company’s consolidated balance sheet. Risks and Uncertainties The Company’s financial statements include estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses. The outcome of certain significant risks and uncertainties could cause the Company to revise its estimates and assumptions or could cause actual results to differ materially from the Company’s estimates. The discussion below highlights the significant risks and uncertainties that could have a material effect on the Company’s financial statements and business objectives in future periods. COVID-19 COVID-19 COVID-19 COVID-19 Insured portfolios The Company continues to assess the financial impact of the pandemic on its operating insurance companies’ overall insured portfolios. Adverse developments on macroeconomic factors resulting from the spread of COVID-19, Federal legislation passed to combat the economic impact of the pandemic has been significant, including the $2.7 trillion Coronavirus Aid, Relief, and Economic Security (“CARES”) Act in 2020, which included significant aid to offset COVID-19 Certain of MBIA Corp.’s structured finance policies, including those in which the underlying principal obligations are comprised of residential or commercial mortgages and mortgage-backed securities (“MBS”), could be negatively impacted by delays or failures of borrowers to make payments of principal and interest when due, or delays or moratoriums on foreclosures or enforcement actions with respect to delinquent or defaulted mortgages imposed by governmental authorities. MBIA Corp. has recorded significant loss reserves on its residential mortgage-backed securities (“RMBS”) and collateralized debt obligations (“CDO”) exposures, and there can be no assurance that these reserves will be sufficient if the pandemic causes further deterioration to the economy. These transactions are also subject to servicer risks, which relate to problems with the transaction’s servicer that could adversely impact performance of the underlying assets. Additionally, several of the Company’s credits, particularly within its international public finance sector, feature large, near term debt-service payments, and there can be no assurance that the liquidity position of MBIA Corp. will enable it to satisfy any claims that arise if the issuers of such credits are unable or unwilling to refinance or repay their obligations. MBIA Corp. has recorded substantial expected recoveries on certain RMBS transactions, and the forbearance options that mortgage borrowers who were facing financial difficulties took advantage of under the CARES Act, may delay or impair collections on these recoveries. Liquidity The Company continues to monitor its cash and liquid asset resources using cash forecasting and stress-scenario testing. Members of the Company’s senior management meet regularly to review liquidity metrics, discuss contingency plans and establish target liquidity levels. It remains uncertain to predict the full long-term impact the pandemic may have on the Company’s future liquidity position and needs. Declines in the market value or rating eligibility of assets pledged against the Company’s obligations as a result of credit market deterioration caused by COVID-19 U.S. Public Finance Market Conditions National continues to monitor and remediate its existing insured portfolio and may also pursue strategic alternatives that could enhance shareholder value. Certain state and local governments and territory obligors that National insures are under financial and budgetary stress. This could lead to an increase in defaults by such entities on the payment of their obligations and losses or impairments on a greater number of National’s insured transactions. National monitors and analyzes these situations and other stressed credits closely, and the overall extent and duration of this stress is uncertain. MBIA Corp. Insured Portfolio MBIA Corp.’s primary objectives are to satisfy all claims by its policyholders and to maximize future recoveries, if any, for its senior lending and surplus note holders, and then its preferred stock holders. MBIA Corp. is executing this strategy by, among other things, taking steps to maximize the collection of recoveries and by reducing and mitigating potential losses on its insurance exposures. MBIA Corp.’s insured portfolio performance could deteriorate and result in additional significant loss reserves and claim payments. MBIA Corp.’s ability to meet its obligations is limited by available liquidity and its ability to secure additional liquidity through financing and other transactions. There can be no assurance that MBIA Corp. will be successful in generating sufficient resources to meet its obligations. Zohar and RMBS Recoveries Payment of claims on MBIA Corp.’s policies insuring the Class A-1 and A-2 notes issued by Zohar CDO 2003-1, Limited (“Zohar I”) and Zohar II 2005-1, Limited (“Zohar II”), entitles MBIA Corp. to reimbursement of such amounts plus interest and expenses and/or to exercise certain rights and remedies to seek recovery of such amounts. MBIA Corp. anticipates that the primary source of the recoveries will come from the monetization of the assets of Zohar I and Zohar II (the “Zohar Assets”), but there can be no assurance that the monetization of the Zohar Assets will yield amounts sufficient to permit MBIA Corp. to recover a substantial portion of the payments it made on Zohar I and Zohar II. In particular, as the monetization process unfolds and new information concerning the financial condition of the portfolio companies which comprise a significant portion of the Zohar Assets is disclosed, the Company may revise its expectations for recoveries. For example, at a June 3, 2020 hearing, counsel for one of the portfolio companies announced that the monetization process for that company would be delayed as a consequence of having to investigate issues relating to the integrity of the company’s financial statements. MBIA Corp. also projects to collect excess spread from insured RMBS; however, the amount and timing of these collections are uncertain. Failure to collect its expected recoveries could impede MBIA Corp.’s ability to make payments when due on other policies. MBIA Corp. believes that if the New York State Department of Financial Services (“NYSDFS”) concludes at any time that MBIA Insurance Corporation will not be able to pay its policyholder claims, the NYSDFS would likely put MBIA Insurance Corporation into a rehabilitation or liquidation proceeding under Article 74 of the New York Insurance Law (“NYIL”) and/or take such other actions as the NYSDFS may deem necessary to protect the interests of MBIA Insurance Corporation’s policyholders. The determination to commence such a proceeding or take other such actions is within the exclusive control of the NYSDFS. Given the separation of MBIA Inc. and MBIA Corp. as distinct legal entities, the absence of any cross defaults between the entities and the lack of reliance by MBIA Inc. on MBIA Corp. for dividends, the Company does not believe that a rehabilitation or liquidation proceeding with respect to MBIA Insurance Corporation would have any significant liquidity impact on MBIA Inc. Such a proceeding could have material adverse consequences for MBIA Corp., including the termination of derivative contracts for which counterparties may assert market-based claims, the acceleration of debt obligations issued by affiliates and insured by MBIA Corp., the loss of control of MBIA Insurance Corporation to a rehabilitator or liquidator, and unplanned costs. Refer to “Note 5: Loss and Loss Adjustment Expense Reserves” for additional information about MBIA Corp.’s recoveries. Corporate Liquidity Based on the Company’s projections of National’s dividends and other cash inflows, the Company expects that MBIA Inc. will have sufficient cash to satisfy its debt service and general corporate needs. However, MBIA Inc. continues to have liquidity risk that could be caused by interruption of or reduction in dividends from National, deterioration in the performance of invested assets, impaired access to the capital markets, as well as other factors, which are not anticipated at this time. Furthermore, failure by MBIA Inc. to settle liabilities that are insured by MBIA Corp. could result in claims on MBIA Corp.

Significant Accounting Policies

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Significant Accounting Policies	Note 2: Significant Accounting Policies The Company has disclosed its significant accounting policies in “Note 2: Significant Accounting Policies” in the Notes to Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K 10-K. Basis of Presentation The accompanying unaudited consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q S-X 10-K The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at 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. As additional information becomes available or actual amounts become determinable, the recorded estimates are revised and reflected in operating results. The results of operations for the three months ended March 31, 2021 may not be indicative of the results that may be expected for the year ending December 31, 2021. The December 31, 2020 consolidated balance sheet was derived from audited financial statements, but does not include all disclosures required by GAAP for annual periods.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Recent Accounting Pronouncements	Note 3: Recent Accounting Pronouncements Recently Adopted Accounting Standards The Company has not adopted any new accounting pronouncements that had a material impact on its consolidated financial statements. Recent Accounting Developments Reference Rate Reform (Topic 848): Scope (ASU 2021-01) and Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting (ASU 2020-04) In January of 2021, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2021-01, “Reference Rate Reform – Scope,” which clarified the scope and application of the original guidance, ASU 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting,” issued in March of 2020. ASU 2020-04 provides optional expedients and exceptions for applying GAAP to contract modifications and hedging relationships that reference London Interbank Offered Rate (“LIBOR”) or other rates that are expected to be discontinued, subject to meeting certain criteria. Both ASU 2020-04 and ASU 2021-01 were effective upon issuance, and the Company may elect to apply the amendments prospectively through December 31, 2022. The Company is evaluating the impact of adopting ASU 2021-01 and 2020-04.

Variable Interest Entities

Variable Interest Entities	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Variable Interest Entities	Note 4: Variable Interest Entities Primarily through MBIA’s international and structured finance insurance segment, the Company provides credit protection to issuers of obligations that may involve issuer-sponsored special purpose entities (“SPEs”). An SPE may be considered a variable interest entity (“VIE”) to the extent the SPE’s total equity at risk is not sufficient to permit the SPE to finance its activities without additional subordinated financial support or its equity investors lack any one of the following characteristics: (i) the power to direct the activities of the SPE that most significantly impact the entity’s economic performance or (ii) the obligation to absorb the expected losses of the entity or the right to receive the expected residual returns of the entity. A holder of a variable interest or interests in a VIE is required to assess whether it has a controlling financial interest, and thus is required to consolidate the entity as primary beneficiary. An assessment of a controlling financial interest identifies the primary beneficiary as the variable interest holder that has both of the following characteristics: (i) the power to direct the activities of the VIE that most significantly impact the entity’s economic performance and (ii) the obligation to absorb losses of the entity or the right to receive benefits from the entity that could potentially be significant to the VIE. The primary beneficiary is required to consolidate the VIE. An ongoing reassessment of controlling financial interest is required to be performed based on any substantive changes in facts and circumstances involving the VIE and its variable interests. The Company evaluates issuer-sponsored SPEs initially to determine if an entity is a VIE, and is required to reconsider its initial determination if certain events occur. For all entities determined to be VIEs, MBIA performs an ongoing reassessment to determine whether its guarantee to provide credit protection on obligations issued by VIEs provides the Company with a controlling financial interest. Based on its ongoing reassessment of controlling financial interest, the Company determines whether a VIE is required to be consolidated or deconsolidated. The Company makes its determination for consolidation based on a qualitative assessment of the purpose and design of a VIE, the terms and characteristics of variable interests of an entity, and the risks a VIE is designed to create and pass through to holders of variable interests. The Company generally provides credit protection on obligations issued by VIEs, and holds certain contractual rights according to the purpose and design of a VIE. The Company may have the ability to direct certain activities of a VIE depending on facts and circumstances, including the occurrence of certain contingent events, and these activities may be considered the activities of a VIE that most significantly impact the entity’s economic performance. The Company generally considers its guarantee of principal and interest payments of insured obligations, given nonperformance by a VIE, to be an obligation to absorb losses of the entity that could potentially be significant to the VIE. At the time the Company determines it has the ability to direct the activities of a VIE that most significantly impact the economic performance of the entity based on facts and circumstances, MBIA is deemed to have a controlling financial interest in the VIE and is required to consolidate the entity as primary beneficiary. The Company performs an ongoing reassessment of controlling financial interest that may result in consolidation or deconsolidation of any VIE. Consolidated VIEs The carrying amounts of assets and liabilities of consolidated VIEs were $228 million and $474 million, respectively, as of March 31, 2021 and $830 million and $623 million, respectively, as of December 31, 2020. The carrying amounts of assets and liabilities are presented separately in “Assets of consolidated variable interest entities” and “Liabilities of consolidated variable interest entities” on the Company’s consolidated balance sheets. VIEs are consolidated or deconsolidated based on an ongoing reassessment of controlling financial interest, when events occur or circumstances arise, and whether the ability to exercise rights that constitute power to direct activities of any VIEs are present according to the design and characteristics of these entities. In the first quarter of 2021, there was no consolidation or deconsolidation of VIEs by the Company. In the first quarter of 2020, the Company deconsolidated one Holders of insured obligations of issuer-sponsored VIEs do not have recourse to the general assets of the Company. In the event of nonpayment of an insured obligation issued by a consolidated VIE, the Company is obligated to pay principal and interest, when due, on the respective insured obligation only. The Company’s exposure to consolidated VIEs is limited to the credit protection provided on insured obligations and any additional variable interests held by the Company. Nonconsolidated VIEs The following tables present the Company’s maximum exposure to loss for nonconsolidated VIEs and carrying values of the assets and liabilities for its interests in these VIEs in its insurance operations as of March 31, 2021 and December 31, 2020. The maximum exposure to loss as a result of MBIA’s variable interests in VIEs is represented by insurance in force. Insurance in force is the maximum future payments of principal and interest which may be required under commitments to make payments on insured obligations issued by nonconsolidated VIEs. The Company has aggregated nonconsolidated VIEs based on the underlying credit exposure of the insured obligation. The nature of the Company’s variable interests in nonconsolidated VIEs is related to financial guarantees and any investments in obligations issued by nonconsolidated VIEs. March 31, 2021 Carrying Value of Assets Carrying Value of Liabilities In millions Maximum Investments Premiums Insurance Loss Unearned Loss and Loss Insurance: Global structured finance: Mortgage-backed residential $ 1,757 $ 80 $ 16 $ 69 $ 13 $ 428 Consumer asset-backed 277 - 1 1 1 13 Corporate asset-backed 628 - 4 333 5 3 Total global structured finance 2,662 80 21 403 19 444 Global public finance 1,415 - 7 - 7 2 Total insurance $ 4,077 $ 80 $ 28 $ 403 $ 26 $ 446 December 31, 2020 Carrying Value of Assets Carrying Value of Liabilities In millions Maximum Investments Premiums Insurance Loss Unearned Loss and Loss Insurance: Global structured finance: Mortgage-backed residential $ 1,835 $ 21 $ 16 $ 90 $ 14 $ 482 Consumer asset-backed 293 - 1 1 1 15 Corporate asset-backed 735 - 5 364 5 - Total global structured finance 2,863 21 22 455 20 497 Global public finance 1,434 - 7 - 7 2 Total insurance $ 4,297 $ 21 $ 29 $ 455 $ 27 $ 499

Loss and Loss Adjustment Expens

Loss and Loss Adjustment Expense Reserves	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Loss and Loss Adjustment Expense Reserves	Note 5: Loss and Loss Adjustment Expense Reserves U.S. Public Finance Insurance U.S. public finance insured transactions consist of municipal bonds, including tax-exempt Certain state and local governments and territory obligors that National insures are under financial and budgetary stress. In addition, the COVID-19 pandemic may present additional but unknown credit risks to National’s insured portfolio. Puerto Rico had been experiencing significant fiscal stress and constrained liquidity, and in response, the U.S. Congress passed PROMESA. In formulating loss reserves, the Company considers the following: environmental and political impacts; litigation; ongoing discussions with creditors; timing and amount of debt service payments and future recoveries; existing proposed restructuring plans or agreements; and deviations from these proposals in its probability-weighted scenarios. On April 12, 2021, National, other monoline insurers and the Oversight Board reached an agreement in principle settling certain HTA clawback claims in the Commonwealth Title III case and providing for a distribution to HTA holders of cash, bonds and a contingent value instrument and on February 22, 2021, National agreed to join the GO PSA. In September of 2019, National agreed to join the RSA with PREPA, other monoline insurers, a group of uninsured PREPA bondholders, Puerto Rico, and the Oversight Board. Refer to “Note 1: Business Developments and Risks and Uncertainties” for further information on COVID-19 and the Company’s Puerto Rico exposures. Recoveries on Puerto Rico Losses For recoveries on paid Puerto Rico losses, the estimates include assumptions related to the following: economic conditions and trends; political developments; the Company’s ability to enforce contractual rights through litigation and otherwise; discussions with other creditors and the obligors, any existing proposals; and the remediation strategy for an insured obligation that has defaulted or is expected for default. International and Structured Finance Insurance The international and structured finance insurance segment’s case basis reserves and insurance loss recoveries recorded in accordance with GAAP do not include financial guarantee VIEs that are eliminated in consolidation. In addition, COVID-19 may present additional but unknown credit risks to MBIA Corp.’s insured portfolio. Refer to “Note 1: Business Developments and Risks and Uncertainties” for further information on COVID-19. RMBS Case Basis Reserves (Financial Guarantees) The Company’s RMBS reserves and recoveries relate to financial guarantee insurance policies, excluding those on consolidated VIEs. The Company’s first-lien RMBS case basis reserves primarily relate to RMBS backed by alternative A-paper and subprime mortgage loans. The Company’s second-lien RMBS case basis reserves relate to RMBS backed by home equity lines of credit and closed-end second mortgages. The Company calculated RMBS case basis reserves as of March 31, 2021 for both first and second-lien RMBS transactions using a process called the Roll Rate Methodology (“Roll Rate Methodology”). The Roll Rate Methodology is a multi-step process using databases of loan level information, proprietary internal cash flow models, and commercially available models to estimate potential losses and recoveries on insured bonds. Roll Rate is defined as the probability that current loans become delinquent and subsequently default and loans in the delinquent pipeline are charged-off or liquidated. The loss reserve estimates are based on a probability-weighted average of potential scenarios of loan losses. Additional data used for both second and first-liens include historic averages of deal specific voluntary prepayment rates, forward projections of the LIBOR interest rates, and historic averages of deal-specific loss severities. In addition, for second-lien RMBS backed by home equity lines of credit, the Company assumes a constant basis spread between Prime and LIBOR interest rates. Where applicable, the Company factors in termination scenarios when clean up calls are imminent. In calculating ultimate cumulative losses for RMBS, the Company estimates the amount of second-lien loans that are expected to be charged-off (deemed uncollectible by servicers of the transactions) and, for first-lien RMBS, the Company estimates the amount of loans that are expected to be liquidated in the future through foreclosure or short sale. The time to liquidation for a defaulted loan is specific to the loan’s delinquency bucket. For all RMBS transactions, cash flow models consider allocations and other structural aspects and claims against MBIA Corp.’s insurance policy consistent with such policy’s terms and conditions. The estimated net claims from the procedure above are then discounted using a risk-free rate to a net present value reflecting MBIA’s general obligation to pay claims over time and not on an accelerated basis. The Company monitors RMBS portfolio performance on a monthly basis against projected performance, reviewing delinquencies, roll rates, and prepayment rates (including voluntary and involuntary). However, loan performance remains difficult to predict and losses may exceed expectations. In the event of a material deviation in actual performance from projected performance, the Company would increase or decrease the case basis reserves accordingly and re-evaluate its assumptions. RMBS Recoveries The Company’s RMBS recoveries primarily relate to excess spread that is generated from the trust structures in the insured transactions and second-lien “put-back” claims related to those mortgage loans whose inclusion in an insured securitization failed to comply with representations and warranties (“ineligible loans”). As of March 31, 2021, the Company had settled all of its put-back claims relating to the inclusion of ineligible loans in securitizations it insured. See “Second-lien Put-Back Claims Related to Ineligible Loans” below. Excess Spread Excess spread within insured RMBS securitizations is the difference between interest inflows on mortgage loan collateral and interest outflows on the insured RMBS notes. The aggregate amount of excess spread depends on the future loss trends, which include future delinquency trends, average time to charge-off/liquidate charged-off Second-lien Put-Back Claims Related to Ineligible Loans During the first quarter of 2021, the Company entered into a settlement agreement with Credit Suisse related to its put-back claims. In the litigation brought to pursue these claims, Credit Suisse had challenged the Company’s assessment of the ineligibility of individual mortgage loans. In November of 2020, following a trial and post-trial briefing, the court overseeing the litigation issued a decision declaring that MBIA Corp. had succeeded in establishing that a majority of the loans in the transaction were ineligible. In January of 2021, the Court issued an order declaring that Credit Suisse was liable to MBIA for approximately million in damages. On February 9, 2021, the parties to the litigation entered into a settlement agreement pursuant to which Credit Suisse paid MBIA Corp. million, and on February 11, 2021, the court entered an order dismissing the case. Refer to “Note 13: Commitments and Contingencies” for further information about the Company’s litigation with Credit Suisse. As of December 31, 2020, the Company consolidated the RMBS securitization originated by Credit Suisse as a VIE and, therefore, eliminates its estimate of recoveries from its insurance accounting and reflects such recoveries in its accounting for the loan repurchase commitments asset of the VIE using a fair value measurement. CDO Reserves and Recoveries The Company also has loss and LAE reserves on certain transactions within its CDO portfolio, primarily its multi-sector CDO asset class that was insured in the form of financial guarantee policies. MBIA’s insured multi-sector CDOs are transactions that include a variety of collateral ranging from corporate bonds to structured finance assets (which includes, but are not limited to, RMBS, commercial mortgage-backed securities (“CMBS”), ABS and CDO collateral). The Company’s process for estimating reserves and credit impairments on these policies is determined as the present value of the probability-weighted potential future losses, net of estimated recoveries, across multiple scenarios. The Company considers several factors when developing the range of potential outcomes and their impact on MBIA. A range of loss scenarios is considered under different default and severity rates for each transaction’s collateral. Additionally, each transaction is evaluated for its commutation potential. Zohar Recoveries MBIA Corp. is seeking to recover the payments it made (plus interest and expenses) with respect to Zohar I and Zohar II. In March of 2018, the then-director of Zohar I and Zohar II placed those funds into voluntary bankruptcy proceedings in federal bankruptcy court in the District of Delaware (the “Zohar Funds Bankruptcy Cases”). Salvage and subrogation recoveries related to Zohar I and Zohar II are reported within “Insurance loss recoverable” on the Company’s consolidated balance sheet. The Company’s estimate of the insurance loss recoverable for Zohar I and Zohar II includes probability-weighted scenarios of the ultimate monetized recovery from the Zohar Assets. Notwithstanding the monetization procedures agreed to in the Zohar Funds Bankruptcy Cases and confirmed by the court, there can be no assurance that the monetization of the Zohar Assets will yield amounts sufficient to permit MBIA Corp. to recover a substantial portion of the payments it made on Zohar I and Zohar II. In particular, as the monetization process unfolds and new information concerning the financial condition of the portfolio companies is disclosed, the Company may revise its expectations for recoveries. For example, at a June 3, 2020 hearing, counsel for one of the portfolio companies announced that the monetization process for that company would be delayed as a consequence of having to investigate issues relating to the integrity of the company’s financial statements. Failure to recover a substantial portion of the payments made on Zohar I and Zohar II could impede MBIA Corp.’s ability to make payments when due on other policies. MBIA Corp. believes that if the NYSDFS concludes at any time that MBIA Insurance Corporation will not be able to pay its policyholder claims, the NYSDFS would likely put MBIA Insurance Corporation into a rehabilitation or liquidation proceeding under Article 74 of the NYIL and/or take such other actions as the NYSDFS may deem necessary to protect the interests of MBIA Insurance Corporation’s policyholders. The determination to commence such a proceeding or take other such actions is within the exclusive control of the NYSDFS. Summary of Loss and LAE Reserves and Recoveries The Company’s loss and LAE reserves and recoveries before consolidated VIE eliminations, along with amounts that were eliminated as a result of consolidating VIEs for the international and structured finance insurance segment, which are included in the Company’s consolidated balance sheets as of March 31, 2021 and December 31, 2020 are presented in the following table: As of March 31, 2021 As of December 31, 2020 In millions Balance Sheet Line Item Balance Sheet Line Item Insurance Loss and (2) Insurance Loss and (2) U.S. Public Finance Insurance $ 1,216 $ 524 $ 1,220 $ 469 International and Structured Finance Insurance: Before VIE eliminations (1) 426 705 1,082 780 VIE eliminations (1) (20 ) (239 ) (625 ) (259 ) Total international and structured finance insurance 406 466 457 521 Total $ 1,622 $ 990 $ 1,677 $ 990 (1) - Includes loan repurchase commitments of $604 million as of December 31, 2020. (2) - Amounts are net of expected recoveries. Changes in Loss and LAE Reserves The following table presents changes in the Company’s loss and LAE reserves for the three months ended March 31, 2021. Changes in loss and LAE reserves, with the exception of loss and LAE payments are recorded in “Losses and loss adjustment” expenses in the Company’s consolidated statements of operations. As of March 31, 2021, the weighted average risk-free rate used to discount the Company’s loss reserves (claim liability) was 1.56%. LAE reserves are generally expected to be settled within a one-year In millions Changes in Loss and LAE Reserves for the Three Months Ended March 31, 2021 Gross Loss and Reserves as of December 31, (1) Loss Accretion of Changes in Changes in Changes in Other Gross Loss and Reserves as of (1) $990 $(55) $3 $(11) $57 $- $6 $990 (1) - Includes changes in amount and timing of estimated payments and recoveries. The Company’s loss and LAE reserves remained flat for the three months ended March 31, 2021, however, there was an increase in expected payments as well as unfavorable changes in future recoveries of unpaid losses due to the increase in risk-free discount rates, on certain Puerto Rico exposures. This increase was partially offset by actual payments made and a decrease in expected payments related to certain insured first-lien RMBS transactions as a result of the increase in risk-free rates used to present value loss reserves during the quarter. Changes in Insurance Loss Recoverable Insurance loss recoverable represents the Company’s estimate of recoveries on paid claims and LAE. The Company recognizes potential recoveries on paid claims based on the probability-weighted net cash inflows present valued at applicable risk-free rates as of the measurement date. The following table presents changes in the Company’s insurance loss recoverable for the three months ended March 31, 2021. Changes in insurance loss recoverable with the exception of collections, are recorded in “Losses and loss adjustment” expenses in the Company’s consolidated statements of operations. Changes in Insurance Loss Recoverable for the Three Months Ended March 31, 2021 In millions Gross Collections Accretion Changes in Changes in (1) Other (2) Gross Insurance loss recoverable $ 1,677 $ (14 ) $ 3 $ (98 ) $ 53 $ 1 $ 1,622 (1) - Includes amounts related to paid claims. (2) - Primarily changes in amount and timing of collections and LAE. The decrease in the Company’s insurance loss recoverable reflected in the preceding table was primarily due to an increase in risk-free rates which caused future recoveries on paid claims to decline, and a decrease in expected recovery assumptions on CDOs. This decrease was partially offset by a change in expected recovery assumptions related to paid claims on certain Puerto Rico credits. Loss and LAE Activity For the three months ended March 31, 2021, loss and LAE incurred primarily related to a decrease in future recoveries on unpaid and paid losses due to an increase in risk-free discount rates and an increase in expected payments on certain Puerto Rico credits as well as a decrease in expected salvage collections related to CDOs. This was partially offset by a decrease in the present value of loss reserves, primarily related to first-lien RMBS transactions, as a result of the increase in risk-free discount rates. For the three months ended March 31, 2020, loss and LAE incurred primarily related to a decrease in expected salvage collections related to CDOs, as well as declines in risk-free rates during the quarter which increased the present value of the loss reserves, primarily related to first-lien RMBS transactions. Costs associated with remediating insured obligations assigned to the Company’s surveillance categories are recorded as LAE and are included in “Losses and loss adjustment” expenses on the Company’s consolidated statements of operations. For the three months ended March 31, 2021 and 2020, gross LAE related to remediating insured obligations were $12 million and $9 million, respectively. Surveillance Categories The following table provides information about the financial guarantees and related claim liability included in each of MBIA’s surveillance categories as of March 31, 2021: Surveillance Categories $ in millions Caution Caution Caution High Classified List Total Number of policies 46 16 - 217 279 Number of issues (1) 16 3 - 98 117 Remaining weighted average contract period (in years) 6.3 6.1 - 7.8 7.3 Gross insured contractual payments outstanding: (2) Principal $ 1,390 $ 123 $ - $ 3,251 $ 4,764 Interest 1,933 53 - 1,370 3,356 Total $ 3,323 $ 176 $ - $ 4,621 $ 8,120 Gross Claim Liability (3) $ - $ - $ - $ 1,010 $ 1,010 Less: Gross Potential Recoveries (4) - - - 2,115 2,115 Discount, net (5) - - - (464 ) (464 ) Net claim liability (recoverable) $ - $ - $ - $ (641 ) $ (641 ) Unearned premium revenue $ 9 $ - $ - $ 34 $ 43 Reinsurance recoverable on paid and unpaid losses (6) $ 11 (1) - An “issue” represents the aggregate of financial guarantee policies that share the same revenue source for purposes of making debt service payments on the insured debt. (2) - Represents contractual principal and interest payments due by the issuer of the obligations insured by MBIA. (3) - The gross claim liability with respect to Puerto Rico exposures are net of expected recoveries for policies in a net payable position. (4) - Gross potential recoveries with respect to certain Puerto Rico exposures are net of the claim liability for policies in a net recoverable position. (5) - Represents discount related to Gross Claim Liability and Gross Potential Recoveries. (6) - Included in “Other assets” on the Company’s consolidated balance sheets. The following table provides information about the financial guarantees and related claim liability included in each of MBIA’s surveillance categories as of December 31, 2020: Surveillance Categories $ in millions Caution Caution Caution Classified List Total Number of policies 46 16 - 219 281 Number of issues (1) 16 3 - 100 119 Remaining weighted average contract period (in years) 6.4 6.4 - 7.9 7.4 Gross insured contractual payments outstanding: (2) Principal $ 1,422 $ 123 $ - $ 3,302 $ 4,847 Interest 1,974 54 - 1,441 3,469 Total $ 3,396 $ 177 $ - $ 4,743 $ 8,316 Gross Claim Liability (3) $ - $ - $ - $ 1,088 $ 1,088 Less: Gross Potential Recoveries (4) - - - 1,947 1,947 Discount, net (5) - - - (173 ) (173 ) Net claim liability (recoverable) $ - $ - $ - $ (686 ) $ (686 ) Unearned premium revenue $ 10 $ - $ - $ 35 $ 45 Reinsurance recoverable on paid and unpaid losses (6) $ 11 (1) - An “issue” represents the aggregate of financial guarantee policies that share the same revenue source for purposes of making debt service payments on the insured debt. (2) - Represents contractual principal and interest payments due by the issuer of the obligations insured by MBIA. (3) - The gross claim liability with respect to Puerto Rico exposures are net of expected recoveries for policies in a net payable position. (4) - Gross potential recoveries with respect to certain Puerto Rico exposures are net of the claim liability for policies in a net recoverable position. (5) - Represents discount related to Gross Claim Liability and Gross Potential Recoveries. (6) - Included in “Other assets” on the Company’s consolidated balance sheets.

Fair Value Of Financial Instrum

Fair Value Of Financial Instruments	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Fair Value Measurement	Note 6: Fair Value of Financial Instruments Fair Value Measurement Financial Assets and Liabilities Financial assets held by the Company primarily consist of investments in debt securities, loans receivables at fair value and loan repurchase commitments held by consolidated VIEs. The Company’s remaining loan repurchase commitments were settled in the first quarter of 2021. Financial liabilities, excluding derivative liabilities, issued by the Company primarily consist of debt issued for general corporate purposes within its corporate segment, medium-term notes (“MTNs”), investment agreements and debt issued by consolidated VIEs. The Company’s derivative liabilities are primarily interest rate swaps and insured credit derivatives. Valuation Techniques Valuation techniques for financial instruments measured at fair value are described below. Fixed-Maturity Securities Held as Available-For-Sale, Investments Carried at Fair Value, Investments Pledged as Collateral and Short-term Investments These investments include investments in U.S. Treasury and government agencies, state and municipal bonds, foreign governments, corporate obligations, MBS, ABS, money market securities, and perpetual debt and equity securities. Substantially all of these investments are valued based on recently executed transaction prices or quoted market prices by independent third parties, including pricing services and brokers. When quoted market prices are not available, fair value is generally determined using quoted prices of similar investments or a valuation model based on observable and unobservable inputs. Inputs vary depending on the type of investment. Observable inputs include contractual cash flows, interest rate yield curves, CDS spreads, prepayment and volatility scores, diversity scores, cross-currency basis index spreads, and credit spreads for structures similar to the financial instrument in terms of issuer, maturity and seniority. Unobservable inputs include cash flow projections and the value of any credit enhancement. Investments based on quoted market prices of identical investments in active markets are classified as Level 1 of the fair value hierarchy. Level 1 investments generally consist of U.S. Treasury and government agency, money market securities and perpetual debt and equity securities. Quoted market prices of investments in less active markets, as well as investments which are valued based on other than quoted prices for which the inputs are observable, such as interest rate yield curves, are categorized in Level 2 of the fair value hierarchy. Investments that contain significant inputs that are not observable are categorized as Level 3. Cash and Cash Equivalents The carrying amounts of cash and cash equivalents approximate fair value due to the short-term nature and credit worthiness of these instruments and are categorized in Level 1 of the fair value hierarchy. Loans Receivable at Fair Value Loans receivable at fair value are comprised of loans and other instruments held by consolidated VIEs, consisting of residential mortgage loans and are categorized in Level 3 of the fair value hierarchy. Fair values of residential mortgage loans are determined using quoted prices for MBS issued by the respective VIE and adjusted for the fair values of the financial guarantees provided by MBIA Corp. on the related MBS. The fair values of the financial guarantees consider expected claim payments, net of recoveries, under MBIA Corp.’s policies. Loan Repurchase Commitments Loan repurchase commitments are obligations owed by the sellers/servicers of mortgage loans to MBIA as reimbursement of paid claims. Loan repurchase commitments were assets of the consolidated VIEs. These assets represented the rights of MBIA against the sellers/servicers for breaches of representations and warranties that the securitized residential mortgage loans sold to the trust to comply with stated underwriting guidelines and for the sellers/servicers to cure, replace, or repurchase mortgage loans. Fair value measurements of loan repurchase commitments represented the amounts owed by the sellers/servicers to MBIA as reimbursement of paid claims and contractual interest. Loan repurchase commitments were not securities and no quoted prices or comparable market transaction information were observable or available. Fair values of loan repurchase commitments were determined using discounted cash flow techniques and were categorized in Level 3 of the fair value hierarchy. The Company’s loan repurchase commitments were settled in the first quarter of 2021. Other Assets A VIE consolidated by the Company has entered into a derivative instrument consisting of a cross currency swap. The cross currency swap is entered into to manage the variability in cash flows resulting from fluctuations in foreign currency rates. The fair value of the VIE derivative is determined based on inputs from unobservable cash flows projection of the derivative, discounted using observable discount rates. As the significant inputs are unobservable, the derivative contract is categorized in Level 3 of the fair value hierarchy. Other assets also include receivables representing the right to receive reimbursement payments on claim payments expected to be made on certain insured VIE liabilities due to risk mitigating transactions with third parties executed to effectively defease, or, in-substance commute the Company’s exposure on its financial guarantee policies. The right to receive reimbursement payments is based on the value of the Company’s financial guarantee determined using the cash flow model. The fair value of the financial guarantee primarily contains unobservable inputs and is categorized in Level 3 of the fair value hierarchy. Medium-term Notes at Fair Value The Company has elected to measure certain MTNs at fair value on a recurring basis. The fair values of certain MTNs are based on quoted market prices provided by third-party sources, where available. When quoted market prices are not available, the Company applies a matrix pricing grid to determine fair value based on the quoted market prices received for similar instruments and considering the MTNs’ stated maturity and interest rate. Nonperformance risk is included in the quoted market prices and the matrix pricing grid. MTNs are categorized in Level 3 of the fair value hierarchy and do not include accrued interest. Variable Interest Entity Notes The fair values of VIE notes are determined based on recently executed transaction prices or quoted prices where observable. When position-specific quoted prices are not observable, fair values are based on quoted prices of similar securities. Fair values based on quoted prices of similar securities may be adjusted for factors unique to the securities, including any credit enhancement. Observable inputs include interest rate yield curves and bond spreads of similar securities. Unobservable inputs include the value of any credit enhancement. VIE notes are categorized in Level 2 or Level 3 of the fair value hierarchy based on the lowest level input that is significant to the fair value measurement in its entirety. Derivatives The corporate segment has entered into derivative transactions primarily consisting of interest rate swaps. Fair values of over-the-counter derivatives are determined using valuation models based on observable inputs, nonperformance risk of the Company and nonperformance risk of the counterparties. Observable and market-based inputs include interest rate yields, credit spreads and volatilities. These derivatives are categorized in Level 2 or Level 3 of the fair value hierarchy based on the lowest level input that is significant to the fair value measurement in its entirety. Derivatives—Insurance The derivative contracts insured by the Company cannot be legally traded and generally do not have observable market prices. The Company determines the fair values of certain insured credit derivatives using valuation models based on observable inputs and considering nonperformance risk of the Company. These insured credit derivatives are categorized in Level 2 of the fair value hierarchy. Derivatives—Other The Company also had other derivative liabilities as a result of a commutation that occurred in 2014. The fair value of these derivative liabilities were determined using a discounted cash flow model. Key inputs included unobservable cash flows projected over the expected term of the derivative. As the significant inputs were unobservable, the derivative contract was categorized in Level 3 of the fair value hierarchy. These derivative liabilities were settled in the first quarter of 2021. Significant Unobservable Inputs The following tables provide quantitative information regarding the significant unobservable inputs used by the Company for assets and liabilities measured at fair value on a recurring basis as of March 31, 2021 and December 31, 2020: In millions Fair Value as of 2021 Valuation Techniques Unobservable Input Range (Weighted Average) Assets of consolidated VIEs: Loans receivable at fair value $ 124 Market prices adjusted for financial guarantees provided to VIE obligations Impact of financial guarantee (2) -26% - 84% (20%) (1) Liabilities of consolidated VIEs: Variable interest entity notes 280 Market prices of VIE assets adjusted for financial guarantees provided Impact of financial guarantee 30% - 73% (59%) (1) (1) - Weighted average represents the total MBIA guarantees as a percentage of total instrument fair value. (2) - Negative percentage represents financial guarantee policies in a receivable position. In millions Fair Value as of Valuation Techniques Unobservable Input Range (Weighted Average) Assets of consolidated VIEs: Loans receivable at fair value $ 120 Market prices adjusted for financial guarantees provided to VIE obligations Impact of financial guarantee (2) -28% - 109% (22%) (1) Loan repurchase commitments 604 Discounted cash flow Recovery value (3) Liabilities of consolidated VIEs: Variable interest entity notes 303 Market prices of VIE assets adjusted for financial guarantees provided Impact of financial guarantee 30% - (1) Other derivative liabilities 49 Discounted cash flow Cash flows $49 - (1) - Weighted average represents the total MBIA guarantees as a percentage of total instrument fair value. (2) - Negative percentage represents financial guarantee policies in a receivable position. (3) - Recovery value reflects an estimate of the amount to be awarded to the Company as part of litigation seeking to enforce its contractual rights. Sensitivity of Significant Unobservable Inputs The significant unobservable input used in the fair value measurement of the Company’s residential loans receivable at fair value of consolidated VIEs is the impact of the financial guarantee. The fair value of residential loans receivable is calculated by subtracting the value of the financial guarantee from the market value of VIE liabilities. The value of a financial guarantee is estimated by the Company as the present value of expected cash payments, net of recoveries, under the policy. If there had been a lower expected cash flow on the underlying loans receivable of the VIE, the value of the financial guarantee provided by the Company under the insurance policy would have been higher. This would have resulted in a lower fair value of the residential loans receivable in relation to the obligations of the VIE. As of December 31, 2020, the significant unobservable input used in the fair value measurement of the Company’s loan repurchase commitments of consolidated VIEs was a recovery value, which reflected an estimate of the amount to be awarded to the Company as part of litigation seeking to enforce its contractual rights. The Company’s remaining loan repurchase commitments were settled in the first quarter of 2021 for $600 million. The significant unobservable input used in the fair value measurement of the Company’s VIE notes of consolidated VIEs is the impact of the financial guarantee. The fair value of VIE notes is calculated by adding the value of the financial guarantee to the market value of VIE assets. The value of a financial guarantee is estimated by the Company as the present value of expected cash payments under the policy. If the value of the guarantee provided by the Company to the obligations issued by the VIE had increased, the credit support would have added value to the liabilities of the VIE. This would have resulted in an increased fair value of the liabilities of the VIE. As of December 31, 2020, the significant unobservable input used in the fair value measurement of MBIA Corp.’s other derivatives, which were valued using a discounted cash flow model, was the estimates of future cash flows discounted using market rates and CDS spreads. This derivative contract was settled in the first quarter of 2021 for an amount consistent with the reported amount as of December 31, 2020. The following tables present the fair value of the Company’s assets (including short-term investments) and liabilities measured and reported at fair value on a recurring basis as of March 31, 2021 and December 31, 2020: Fair Value Measurements at Reporting Date Using In millions Quoted Prices in Significant Significant (Level 3) Balance as of Assets: Fixed-maturity investments: U.S. Treasury and government agency $ 955 $ 99 $ - $ 1,054 State and municipal bonds - 185 - 185 Foreign governments - 17 - 17 Corporate obligations - 984 - 984 Mortgage-backed securities: Residential mortgage-backed agency - 296 - 296 Residential mortgage-backed non-agency - 90 - 90 Commercial mortgage-backed - 14 - 14 Asset-backed securities: Collateralized debt obligations - 125 - 125 Other asset-backed - 193 - 193 Total fixed-maturity investments 955 2,003 - 2,958 Money market securities 30 - - 30 Perpetual debt and equity securities 40 24 - 64 Cash and cash equivalents 116 - - 116 Derivative assets: Non-insured Interest rate derivatives - 1 - 1 Fair Value Measurements at Reporting Date Using In millions Quoted Prices in (Level 1) Significant Significant (Level 3) Balance as of Assets of consolidated VIEs: Corporate obligations - 6 - 6 Mortgage-backed securities: Residential mortgage-backed non-agency - 38 - 38 Commercial mortgage-backed - 16 - 16 Asset-backed securities: Collateralized debt obligations - 8 - 8 Other asset-backed - 8 - 8 Cash 5 - - 5 Loans receivable at fair value: Residential loans receivable - - 124 124 Other assets: Currency derivatives - - 9 9 Other - - 14 14 Total assets $ 1,146 $ 2,104 $ 147 $ 3,397 Liabilities: Medium-term notes $ - $ - $ 105 $ 105 Derivative liabilities: Insured derivatives: Credit derivatives - 1 - 1 Non-insured Interest rate derivatives - 125 - 125 Liabilities of consolidated VIEs: Variable interest entity notes - 45 280 325 Total liabilities $ - $ 171 $ 385 $ 556 Fair Value Measurements at Reporting Date Using In millions Quoted Prices in Significant Significant (Level 3) Balance as of Assets: Fixed-maturity investments: U.S. Treasury and government agency $ 750 $ 105 $ - $ 855 State and municipal bonds - 195 - 195 Foreign governments - 15 - 15 Corporate obligations - 975 - 975 Mortgage-backed securities: Residential mortgage-backed agency - 319 - 319 Residential mortgage-backed non-agency - 32 - 32 Commercial mortgage-backed - 20 - 20 Asset-backed securities: Collateralized debt obligations - 121 - 121 Other asset-backed - 141 - 141 Total fixed-maturity investments 750 1,923 - 2,673 Money market securities 1 - - 1 Perpetual debt and equity securities 37 25 - 62 Cash and cash equivalents 158 - - 158 Derivative assets: Non-insured Interest rate derivatives - 1 - 1 Fair Value Measurements at Reporting Date Using In millions Quoted Prices in (Level 1) Significant Significant (Level 3) Balance as of Assets of consolidated VIEs: Corporate obligations - 6 - 6 Mortgage-backed securities: Residential mortgage-backed non-agency - 40 - 40 Commercial mortgage-backed - 16 - 16 Asset-backed securities: Collateralized debt obligations - 8 - 8 Other asset-backed - 7 - 7 Cash 9 - - 9 Loans receivable at fair value: Residential loans receivable - - 120 120 Loan repurchase commitments - - 604 604 Other assets: Currency derivatives - - 6 6 Other - - 14 14 Total assets $ 955 $ 2,026 $ 744 $ 3,725 Liabilities: Medium-term notes $ - $ - $ 110 $ 110 Derivative liabilities: Insured derivatives: Credit derivatives - 2 - 2 Non-insured Interest rate derivatives - 164 - 164 Other - - 49 49 Liabilities of consolidated VIEs: Variable interest entity notes - 47 303 350 Total liabilities $ - $ 213 $ 462 $ 675 Level 3 assets at fair value as of March 31, 2021 and December 31, 2020 represented approximately 4% and 20%, respectively, of total assets measured at fair value. Level 3 liabilities at fair value as of March 31, 2021 and December 31, 2020 represented approximately 69% and 68%, respectively, of total liabilities measured at fair value. The following tables present the fair values and carrying values of the Company’s assets and liabilities that are disclosed at fair value but not reported at fair value on the Company’s consolidated balance sheets as of March 31, 2021 and December 31, 2020. The majority of the financial assets and liabilities that the Company requires fair value reporting or disclosures are valued based on the estimated value of the underlying collateral, the Company’s or a third-party’s estimate of discounted cash flow model estimates, or quoted market values for similar products. Fair Value Measurements at Reporting Date Using In millions Quoted Prices in (Level 1) Significant Significant Fair Value Carry Value Liabilities: Long-term debt $ - $ 736 $ - $ 736 $ 2,258 Medium-term notes - - 395 395 590 Investment agreements - - 353 353 268 Liabilities of consolidated VIEs: Variable interest entity notes - 129 - 129 126 Total liabilities $ - $ 865 $ 748 $ 1,613 $ 3,242 Financial Guarantees: Gross liability (recoverable) $ - $ - $ 874 $ 874 $ (246 ) Ceded recoverable (liability) - - 45 45 (19 ) Fair Value Measurements at Reporting Date Using In millions Quoted Prices in (Level 1) Significant Other Significant Fair Value Carry Value Liabilities: Long-term debt $ - $ 631 $ - $ 631 $ 2,229 Medium-term notes - - 396 396 598 Investment agreements - - 376 376 269 Liabilities of consolidated VIEs: Variable interest entity notes - 276 - 276 273 Total liabilities $ - $ 907 $ 772 $ 1,679 $ 3,369 Financial Guarantees: Gross liability (recoverable) $ - $ - $ 811 $ 811 $ (282 ) Ceded recoverable (liability) - - 45 45 (17 ) The following tables present information about changes in Level 3 assets (including short-term investments) and liabilities measured at fair value on a recurring basis for the three months ended March 31, 2021 and 2020: Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis for the Three Months Ended March 31, 2021 In millions Balance, Total Unrealized (1) Purchases Issuances Settlements Sales Transfers Transfers Ending Change in still held as Change in still held as of (1) Assets: Assets of consolidated VIEs: Loans receivable- residential $ 120 $ 9 $ - $ - $ - $ (5 ) $ - $ - $ - $ 124 $ 8 $ - Loan repurchase commitments 604 (4 ) - - - (600 ) - - - - - - Currency derivatives 6 3 - - - - - - - 9 3 - Other 14 - - - - - - - - 14 - - Total assets $ 744 $ 8 $ - $ - $ - $ (605 ) $ - $ - $ - $ 147 $ 11 $ - In millions Balance, Total Unrealized (2) Purchases Issuances Settlements Sales Transfers Transfers Ending Change in March 31, Change in the Period (2) Liabilities: Medium-term notes $ 110 $ (7 ) $ 2 $ - $ - $ - $ - $ - $ - $ 105 $ (7 ) $ 2 Other derivatives 49 - - - - (49 ) - - - - - - Liabilities of consolidated VIEs: VIE notes 303 22 (16 ) - - (29 ) - - - 280 4 3 Total liabilities $ 462 $ 15 $ (14 ) $ - $ - $ (78 ) $ - $ - $ - $ 385 $ (3 ) $ 5 (1) - Reported within the “Unrealized gains (losses) on available-for-sale securities” on MBIA’s Consolidated Statement of Comprehensive Income/Loss. (2) - Reported within the “Instrument-specific credit risk of liabilities measured at fair value” on MBIA’s Consolidated Statement of Comprehensive Income/Loss. Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis for the Three Months Ended March 31, 2020 In millions Balance, Total Unrealized (1) Purchases Issuances Settlements Sales Transfers Transfers Ending Change in Change in (1) Assets: Other asset-backed $ 1 $ - $ - $ - $ - $ - $ - $ - $ - $ 1 $ - $ - Assets of consolidated VIEs: Loans receivable- 136 (35 ) - - - (3 ) - - - 98 (35 ) - Loan repurchase commitments 486 20 - - - - - - - 506 20 - Currency derivatives 8 10 - - - - - - - 18 10 - Other 18 (3 ) - - - - - - - 15 (3 ) - Total assets $ 649 $ (8 ) $ - $ - $ - $ (3 ) $ - $ - $ - $ 638 $ (8 ) $ - In millions Balance, Total Unrealized (2) Purchases Issuances Settlements Sales Transfers Transfers Ending Change in March 31, Change in (2) Liabilities: Medium-term notes $ 108 $ 2 $ (12 ) $ - $ - $ - $ - $ - $ - $ 98 $ 2 $ (12 ) Credit derivatives 7 1 - - - - - - - 8 1 - Other derivatives 34 3 - - - - - - - 37 3 - Other payable 4 - - - - (4 ) - - - - - - Liabilities of consolidated VIEs: VIE notes 347 (25 ) (36 ) - - (5 ) - - - 281 (28 ) (34 ) Total liabilities $ 500 $ (19 ) $ (48 ) $ - $ - $ (9 ) $ - $ - $ - $ 424 $ (22 ) $ (46 ) (1) - Reported within the “Unrealized gains (losses) on available-for-sale securities” on MBIA’s Consolidated Statement of Comprehensive Income/Loss. (2) - Reported within the “Instrument-specific credit risk of liabilities measured at fair value” on MBIA’s Consolidated Statement of Comprehensive Income/Loss. For the three months ended March 31, 2021 and 2020, there were no transfers into or out of Level 3. Gains and losses (realized and unrealized) included in earnings related to Level 3 assets and liabilities for the three months ended March 31, 2021 and 2020 are reported on the Company’s consolidated statements of operations as follows: Three Months Ended March 31, 2021 Three Months Ended March 31, 2020 In millions Total Change in Unrealized 2021 Total Change in Unrealized 2020 Revenues: Unrealized gains (losses) on insured derivatives $ - $ - $ (1 ) $ (1 ) Net gains (losses) on financial instruments at fair value and foreign exchange 7 7 (5 ) (5 ) Revenues of consolidated VIEs: Net gains (losses) on financial instruments at fair value and foreign exchange (14 ) 7 17 20 Total $ (7 ) $ 14 $ 11 $ 14 Fair Value Option The Company elected to record at fair value certain financial instruments that are consolidated in connection with the adoption of the accounting guidance for consolidation of VIEs, among others . The following table presents the gains and (losses) included in the Company’s consolidated statements of operations for the three months ended March 31, 2021 and 2020 for financial instruments for which the fair value option was elected: Three Months Ended March 31, In millions 2021 2020 Investments carried at fair value (1) $ 3 $ (20) Fixed-maturity securities held at fair value-VIE (2) 1 (6) Loans receivable at fair value: Residential mortgage loans (2) 9 (35) Loan repurchase commitments (2) (4) 20 Other assets-VIE (2) - (3) Medium-term notes (1) 7 (2) Variable interest entity notes (2) (23) 27 (1) - Reported within “Net gains (losses) of financial instruments at fair value and foreign exchange” on MBIA’s consolidated statements of operations. (2) - Reported within “Net gains (losses) of financial instruments at fair value and foreign exchange-VIE” on MBIA’s consolidated statements of operations. The following table reflects the difference between the aggregate fair value and the aggregate remaining contractual principal balance outstanding as of March 31, 2021 and December 31, 2020 for loans and notes for which the fair value option was elected: As of March 31, 2021 As of December 31, 2020 Contractual Contractual Outstanding Fair Outstanding Fair In millions Principal Value Difference Principal Value Difference Loans receivable at fair value: Residential mortgage loans - current $ 85 $ 85 $ - $ 89 $ 89 $ - Residential mortgage loans (90 days or more past due) 144 39 105 147 31 116 Total loans receivable and other instruments at fair value $ 229 $ 124 $ 105 $ 236 $ 120 $ 116 Variable interest entity notes $ 1,080 $ 325 $ 755 $ 1,117 $ 350 $ 767 Medium-term notes $ 118 $ 105 $ 13 $ 122 $ 110 $ 12 The differences between the contractual outstanding principal and the fair values on loans receivable, VIE notes and MTNs, in the preceding table, are primarily attributable to credit risk. This is due to the high rate of defaults on loans (90 days or more past due), the collateral supporting the VIE notes and the nonperformance risk of the Company on its MTNs, which resulted in depressed pricing of the financial instruments. Instrument-Specific Credit Risk of Liabilities Elected Under the Fair Value Option As of March 31, 2021 and December 31, 2020, the cumulative changes in instrument-specific credit risk of liabilities elected under the fair value option were losses of $36 million and $51 million, respectively, reported in “Accumulated other comprehensive income” on the Company’s consolidated balance sheets. Changes in value attributable to instrument-specific credit risk were derived principally from changes in the Company’s credit spread. For liabilities of VIEs, additional adjustments to instrument-specific credit risk are required, which is determined by an analysis of deal specific performance of collateral that support these liabilities. During the three months ended March 31, 2021 and 2020, the portions of instrument-specific credit risk included in AOCI that were recognized in earnings due to settlement of liabilities were losses of $20 million and $2 million, respectively.

Investments

Investments	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Investments	Note 7: Investments Investments, excluding those elected under the fair value option, include debt and equity securities classified as AFS. The following tables presents the amortized cost, allowance for credit losses, corresponding gross unrealized gains and losses and fair value for AFS investments in the Company’s consolidated investment portfolio as of March 31, 2021 and December 31, 2020: March 31, 2021 In millions Amortized Allowance Gross Gross Fair AFS Investments Fixed-maturity investments: U.S. Treasury and government agency $ 1,006 $ - $ 47 $ (5 ) $ 1,048 State and municipal bonds 160 - 25 - 185 Foreign governments 13 - - - 13 Corporate obligations 883 - 31 (16 ) 898 Mortgage-backed securities: Residential mortgage-backed agency 285 - 7 (3 ) 289 Residential mortgage-backed non-agency 83 - 4 (3 ) 84 Commercial mortgage-backed 11 - 1 - 12 Asset-backed securities: Collateralized debt obligations 114 - - (1 ) 113 Other asset-backed 173 - - - 173 Total AFS investments $ 2,728 $ - $ 115 $ (28 ) $ 2,815 December 31, 2020 In millions Amortized Allowance Gross Gross Fair AFS Investments Fixed-maturity investments: U.S. Treasury and government agency $ 775 $ - $ 75 $ (1 ) $ 849 State and municipal bonds 162 - 32 - 194 Foreign governments 11 - 1 - 12 Corporate obligations 827 - 64 (1 ) 890 Mortgage-backed securities: Residential mortgage-backed agency 305 - 8 (1 ) 312 Residential mortgage-backed non-agency 22 - 3 - 25 Commercial mortgage-backed 17 - 1 - 18 Asset-backed securities: - Collateralized debt obligations 120 - - (2 ) 118 Other asset-backed 121 - - - 121 Total AFS investments $ 2,360 $ - $ 184 $ (5 ) $ 2,539 Total AFS investments increased as of March 31, 2021 compared to December 31, 2020 primarily due to the investment of proceeds received from the Credit Suisse settlement. The following table presents the distribution by contractual maturity of AFS fixed-maturity securities at amortized cost, net of allowance for credit losses, and fair value as of March 31, 2021. Contractual maturity may differ from expected maturity as borrowers may have the right to call or prepay obligations. AFS Securities In millions Net Fair Due in one year or less $ 827 $ 829 Due after one year through five years 374 387 Due after five years through ten years 231 248 Due after ten years 630 680 Mortgage-backed and asset-backed 666 671 Total fixed-maturity investments $ 2,728 $ 2,815 Deposited and Pledged Securities The fair value of securities on deposit with various regulatory authorities as of March 31, 2021 and December 31, 2020 was $11 million. These deposits are required to comply with state insurance laws. Investment agreement obligations require the Company to pledge securities as collateral. Securities pledged in connection with investment agreements may not be repledged by the investment agreement counterparty. As of March 31, 2021 and December 31, 2020, the fair value of securities pledged as collateral for these investment agreements approximated $278 million and $282 million, respectively. The Company’s collateral as of March 31, 2021 consisted principally of U.S. Treasury and government agency and corporate obligations, and was primarily held with major U.S. banks. Refer to “Note 8: Derivative Instruments” for information about securities posted to derivative counterparties. Impaired Investments The following tables present the non-credit March 31, 2021 Less than 12 Months 12 Months or Longer Total In millions Fair Unrealized Fair Unrealized Fair Unrealized AFS Investments Fixed-maturity investments: U.S. Treasury and government agency $ 125 $ (5 ) $ - $ - $ 125 $ (5 ) State and municipal bonds 4 - - - 4 - Foreign governments 6 - - - 6 - Corporate obligations 278 (15 ) 15 (1 ) 293 (16 ) Mortgage-backed securities: Residential mortgage-backed agency 100 (3 ) - - 100 (3 ) Residential mortgage-backed non-agency 35 (3 ) 1 - 36 (3 ) Commercial mortgage-backed 2 - - - 2 - Asset-backed securities: Collateralized debt obligations 19 - 71 (1 ) 90 (1 ) Other asset-backed 77 - 1 - 78 - Total AFS investments $ 646 $ (26 ) $ 88 $ (2 ) $ 734 $ (28 ) December 31, 2020 Less than 12 Months 12 Months or Longer Total In millions Fair Unrealized Fair Unrealized Fair Unrealized AFS Investments Fixed-maturity investments: U.S. Treasury and government agency $ 99 $ (1 ) $ - $ - $ 99 $ (1 ) Foreign governments 2 - - - 2 - Corporate obligations 103 (1 ) 7 - 110 (1 ) Mortgage-backed securities: Residential mortgage-backed agency 53 (1 ) - - 53 (1 ) Residential mortgage-backed non-agency 2 - 1 - 3 - Commercial mortgage-backed - - 5 - 5 - Asset-backed securities: Collateralized debt obligations 37 - 78 (2 ) 115 (2 ) Other asset-backed 29 - - - 29 - Total AFS investments $ 325 $ (3 ) $ 91 $ (2 ) $ 416 $ (5 ) Gross unrealized losses on AFS investments increased as of March 31, 2021 compared with December 31, 2020 primarily due to higher interest rates, partially offset by tightening credit spreads. With the weighting applied on the fair value of each security relative to the total fair value, the weighted average contractual maturity of securities in an unrealized loss position as of March 31, 2021 and December 31, 2020 was 14 and 9 years, respectively. As of March 31, 2021 and December 31, 2020, there were 45 and 42 securities, respectively, that were in an unrealized loss position for a continuous twelve-month period or longer, of which, fair values of 7 and 9 securities, respectively, were below book value by more than 5%. The following table presents the distribution of securities in an unrealized loss position for a continuous twelve-month period or longer where fair value was below book value by more than 5% as of March 31, 2021: AFS Securities Percentage of Fair Value Below Book Value Number of Book Value Fair Value > 5% to 15% 2 $ 1 $ 1 > 15% to 25% 3 1 1 > 50% 2 - - Total 7 $ 2 $ 2 Impaired securities that the Company intends to sell before the expected recovery of such securities’ fair values have been written down to fair value. As of March 31, 2021, the Company concluded that it does not have the intent to sell securities in an unrealized loss position and it is more likely than not, that it would not have to sell these securities before recovery of their cost basis. In making this conclusion, the Company examined the cash flow projections for its investment portfolios, the potential sources and uses of cash in its businesses, and the cash resources available to its business other than sales of securities. It also considered the existence of any risk management or other plans as of March 31, 2021 that would require the sale of impaired securities. Credit Losses on Investments The Company’s fixed-maturity securities for which fair value is less than amortized cost are reviewed quarterly in order to determine whether a credit loss exists. If the Company determines that the declines in the fair value are related to credit loss, the Company will establish an allowance for credit losses and recognize the credit component through earnings. Refer to “Note 8: Investments” in the Notes to Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 for a discussion of the Company’s policy for its determination of credit losses. The Company does not recognize credit losses on securities insured by MBIA Corp. and National since those securities, whether or not owned by the Company, are evaluated for impairments in accordance with its loss reserving policy. The following table provides information about securities held by the Company as of March 31, 2021 that were in an unrealized loss position and insured by a financial guarantor, along with the amount of insurance loss reserves corresponding to the par amount owned by the Company. The Company did not hold any securities in an unrealized loss position that were insured by a third-party financial guarantor as of March 31, 2021. In millions Fair Unrealized Insurance (1) Mortgage-backed $ 36 $ (3) $ 44 Corporate obligations 85 (10) - Total $ 121 $ (13) $ 44 (1) - Insurance loss reserve estimates are based on the proportion of par value owned to the total amount of par value insured and are discounted using a discount rate equal to the risk-free rate applicable to the currency and weighted average remaining life of the insurance contract and may differ from the fair value. Allowance for Credit Losses Rollforward The Company did not establish an allowance for credit losses for AFS securities as of March 31, 2021 or purchase any credit-deteriorated assets for the three months ended March 31, 2021. The following table presents the rollforward of the allowance for credit losses on HTM investments for the three months ended March 31, 2020. Three Months Ended March 31, 2020 In millions Balance (1) Current Initial Write-Offs Recoveries Balance HTM Investments Assets of consolidated VIEs: Corporate obligations $ 37 $ 9 $ - $ - $ - $ 46 Total Allowance on HTM investments $ 37 $ 9 $ - $ - $ - $ 46 (1) - Represents transition adjustment upon adoption of ASU 2016-13. Sales of Available-for-Sale Investments Gross realized gains and losses are recorded within “Net gains (losses) on financial instruments at fair value and foreign exchange” on the Company’s consolidated statements of operations. The proceeds and the gross realized gains and losses from sales of fixed-maturity securities held as AFS for the three months ended March 31, 2021 and 2020 are as follows: Three Months Ended In millions 2021 2020 Proceeds from sales $ 178 $ 279 Gross realized gains $ 4 $ 11 Gross realized losses $ (5 ) $ (8 ) Equity Investments Unrealized gains and losses recognized on equity investments held as of the end of each period for the three months ended March 31, 2021 and 2020 are as follows: Three In millions 2021 2020 Net gains and (losses) recognized during the period on equity securities $ 2 $ (13 ) Less: Net gains and (losses) recognized during the period on equity securities sold during the period - - Unrealized gains and (losses) recognized during the period on equity securities still held at the reporting date $ 2 $ (13 )

Derivative Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Derivative Instruments	Note 8: Derivative Instruments U.S. Public Finance Insurance The Company’s derivative exposure within its U.S. public finance insurance operations primarily consists of insured interest rate swaps related to insured U.S. public finance debt issues. These derivatives do not qualify for the financial guarantee scope exception and are accounted for as derivative instruments. Changes in the fair values of the Company’s insured derivatives within its U.S. Public Finance segment are included in “Net change in fair value of insured derivatives” on the Company’s consolidated statements of operations. Corporate The Company has entered into derivative instruments primarily consisting of interest rate swaps to manage the risks associated with fluctuations in interest rates affecting the value of certain assets. Changes in the fair values of the Company’s derivatives within its Corporate segment are included in “Net gains (losses) on financial instruments at fair value and foreign exchange” on the Company’s consolidated statements of operations. International and Structured Finance Insurance The Company’s derivative exposure within its international and structured finance insurance segment includes insured interest rate and inflation-linked swaps related to insured debt issues. Changes in the fair values of the Company’s insured derivatives within its International and Structured Finance segment are included in “Net change in fair value of insured derivatives” on the Company’s consolidated statements of operations. The Company had also entered into a derivative contract in connection with the commutation of certain insurance exposure, which occurred in 2014. Changes in the fair value of this non-insured Variable Interest Entities A VIE consolidated by the Company is party to a cross currency swap, which was entered into to manage the variability in cash flows resulting from fluctuations in foreign currency rates. Changes in the fair value of the VIE derivative are included in “Net gains (losses) on financial instruments at fair value and foreign exchange-VIE” Credit Derivatives Sold The following tables present information about credit derivatives sold by the Company’s insurance operations that were outstanding as of March 31, 2021 and December 31, 2020. Credit ratings represent the lower of underlying ratings assigned to the collateral by Moody’s Investor Services (“Moody’s”), Standard & Poor’s Financial Services, LLC (“S&P”) or MBIA. $ in millions As of March 31, 2021 Notional Value Credit Derivatives Sold Weighted AAA AA A BBB Below Total Fair Insured swaps 13.8 Years $ - $ 56 $ 1,311 $ 358 $ - $ 1,725 $ (1 ) Total notional $ - $ 56 $ 1,311 $ 358 $ - $ 1,725 Total fair value $ - $ - $ - $ (1 ) $ - $ (1 ) $ in millions As of December 31, 2020 Notional Value Credit Derivatives Sold Weighted AAA AA A BBB Below Total Fair Insured swaps 13.9 Years $ - $ 58 $ 1,327 $ 358 $ - $ 1,743 $ (2 ) Total notional $ - $ 58 $ 1,327 $ 358 $ - $ 1,743 Total fair value $ - $ - $ (1 ) $ (1 ) $ - $ (2 ) Internal credit ratings assigned by MBIA on the underlying credit exposures are assigned by the Company’s surveillance group. In assigning an internal rating, current status reports from issuers and trustees, as well as publicly available transaction-specific information, are reviewed. The maximum potential amount of future payments (undiscounted) on insured swaps that are primarily insured interest rate swaps is estimated as the net interest settlements plus principal payments where applicable, on amortizing swaps. MBIA may hold recourse provisions through subrogation rights of the swap counterparty, whereby if MBIA makes a claim payment, it may be entitled to receive net swap settlements from the issuer under the swap agreement. Counterparty Credit Risk The Company manages counterparty credit risk on an individual counterparty basis through master netting agreements covering derivative instruments in the corporate segment. These agreements allow the Company to contractually net amounts due from a counterparty with those amounts due to such counterparty when certain triggering events occur. The Company only executes swaps under master netting agreements, which typically contain mutual credit downgrade provisions that generally provide the ability to require assignment or termination in the event either MBIA or the counterparty is downgraded below a specified credit rating. Under these agreements, the Company may receive or provide cash, U.S. Treasury or other highly rated securities to secure counterparties’ exposure to the Company or its exposure to counterparties, respectively. Such collateral is available to the holder to pay for replacing the counterparty in the event that the counterparty defaults. As of March 31, 2021 and December 31, 2020, the Company did not hold or post cash collateral to derivative counterparties. As of March 31, 2021 and December 31, 2020, the Company had securities with a fair value of $154 million and $214 million, respectively, posted to derivative counterparties and these amounts are included within “Fixed-maturity securities held as available-for-sale, As of March 31, 2021 and December 31, 2020, the fair value on one Credit Support Annex (“CSA”) was $1 million. This CSA governs collateral posting requirements between MBIA and its derivative counterparties. The Company did not receive collateral due to the Company’s credit rating, which was below the CSA minimum credit ratings level for holding counterparty collateral. As of March 31, 2021 and December 31, 2020, the counterparty was rated Aa3 by Moody’s and A+ by S&P. Financial Statement Presentation The fair value of amounts recognized for eligible derivative contracts executed with the same counterparty under a master netting agreement, including any cash collateral that may have been received or posted by the Company, is presented on a net basis in accordance with accounting guidance for the offsetting of fair value amounts related to derivative instruments. Insured CDS and insured swaps are not subject to master netting agreements. VIE derivative assets and liabilities are not presented net of any master netting agreements. Counterparty netting of derivative assets and liabilities offsets balances in “Interest rate swaps”, when applicable. The following table presents the total fair value of the Company’s derivative assets and liabilities by instrument and balance sheet location, before counterparty netting, as of March 31, 2021: In millions Derivative Assets (1) Derivative Liabilities (1) Derivative Instruments Notional Balance Sheet Fair Balance Sheet Fair Not designated as hedging instruments: Insured swaps $ 1,725 Other assets $ - Derivative liabilities $ (1 ) Interest rate swaps 429 Other assets 1 Derivative liabilities (125 ) Interest rate swaps-embedded 241 Medium-term notes - Medium-term notes (10 ) Currency swaps-VIE 52 Other assets-VIE 9 Derivative liabilities-VIE - Total non-designated $ 2,447 $ 10 $ (136 ) ( In accordance with the accounting guidance for derivative instruments and hedging activities, the balance sheet location of the Company’s embedded derivative instruments is determined by the location of the related host contract. The following table presents the total fair value of the Company’s derivative assets and liabilities by instrument and balance sheet location, before counterparty netting, as of December 31, 2020: In millions Derivative Assets (1) Derivative Liabilities (1) Derivative Instruments Notional Balance Sheet Fair Balance Sheet Fair Not designated as hedging instruments: Insured swaps $ 1,743 Other assets $ - Derivative liabilities $ (2 ) Interest rate swaps 437 Other assets 1 Derivative liabilities (164 ) Interest rate swaps-embedded 252 Medium-term notes - Medium-term notes (10 ) Currency swaps-VIE 53 Other assets-VIE 6 Derivative liabilities-VIE - All other 49 Other assets - Derivative liabilities (49 ) Total non-designated $ 2,534 $ 7 $ (225 ) (1) - In accordance with the accounting guidance for derivative instruments and hedging activities, the balance sheet location of the Company’s embedded derivative instruments is determined by the location of the related host contract. The following table presents the effect of derivative instruments on the consolidated statements of operations for the three months ended March 31, 2021 and 2020: In millions Derivatives Not Designated as Three Months Ended March 31, Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivative 2021 2020 Insured credit default swaps Unrealized gains (losses) on insured derivatives $ - $ (1 ) Interest rate swaps Net gains (losses) on financial instruments at fair value and foreign exchange 35 (56 ) Currency swaps-VIE Net gains (losses) on financial instruments at fair value and foreign exchange-VIE 2 10 All other Net gains (losses) on financial instruments at fair value and foreign exchange - (3 ) Total $ 37 $ (50 )

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Note 9: Income Taxes The Company’s income taxes and the related effective tax rates for the three months ended March 31, 2021 and 2020 are as follows: Three Months Ended March 31, In millions 2021 2020 Income (loss) before income taxes $ (106 ) $ (333 ) Provision (benefit) for income taxes $ - $ - Effective tax rate 0.0% 0.0% For the three months ended March 31, 2021 and 2020, the Company’s effective tax rate applied to its loss before income taxes was lower than the U.S. statutory tax rate due to the full valuation allowance on the changes in its net deferred tax asset. Deferred Tax Asset, Net of Valuation Allowance The Company assesses the available positive and negative evidence to estimate whether sufficient future taxable income will be generated to permit use of its existing deferred tax assets. A significant piece of objective negative evidence evaluated was the Company having a three-year cumulative loss. Such objective evidence limits the ability to consider other subjective evidence, such as the Company’s projections of pre-tax NOLs of property and casualty insurance companies are permitted to be carried back two years and carried forward 20 years, except where modified by the CARES Act as outlined below. NOLs of property and casualty insurance companies are not subject to the 80 percent taxable income limitation and indefinite lived carryforward period required by the Tax Cuts and Jobs Act applicable to general corporate NOLs . Accounting for Uncertainty in Income Taxes The Company’s policy is to record and disclose any change in unrecognized tax benefit (“UTB”) and related interest and/or penalties to income tax in the consolidated statements of operations. The Company includes interest as a component of income tax expense. As of March 31, 2021 and December 31, 2020, the Company had no UTB. Federal income tax returns through 2011 have been examined or surveyed. As of March 31, 2021, the Company’s NOL is approximately $3.2 billion. NOLs generated prior to tax reform and property and casualty NOLs generated after tax reform will expire between tax years 2031 through 2041. As of March 31, 2021, the Company has a foreign tax credit carryforward of $61 million, which will expire between tax years 2021 through 2030. Section 382 of the Internal Revenue Code On May 2, 2018, MBIA Inc.’s shareholders ratified an amendment to the Company’s By-Laws, 5 COVID-19 Tax Impact On March 27, 2020, as part of the business stimulus package in response to COVID-19, the U.S. government enacted the CARES Act. The CARES Act established new tax provisions including, but not limited to: (1) five-year carryback of NOLs generated in 2018, 2019 and 2020; (2) accelerated refund of alternative minimum tax (“AMT”) credit carryforwards; and (3) retroactive changes to allow accelerated depreciation for certain depreciable property. The legislation did not have a material impact on the Company’s tax positions due to the lack of taxable income in the carryback periods. On December 21, 2020, The Consolidated Appropriations Act (“Act”) passed by Congress to respond to the health and economic impacts of COVID-19. The Act includes a number of tax law changes, including the expansion of Employee Retention Credit, important changes to Paycheck Protection Program, and extension of a variety of expiring tax provisions. On March 6, 2021, The American Rescue Plan Act was passed by Congress to further respond to the health and economic impacts of COVID-19. Among other changes, the legislation provides for an extension of the Employee Retention Credit through 2021. These two legislations do not have a material impact on the Company’s tax positions.

Business Segments

Business Segments	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Business Segments	Note 10: Business Segments As defined by segment reporting, an operating segment is a component of a company (i) that engages in business activities from which it earns revenue and incurs expenses, (ii) whose operating results are regularly reviewed by the Chief Operating Decision Maker to assess the performance of the segment and to make decisions about the allocation of resources to the segment and, (iii) for which discrete financial information is available. The Company manages its businesses across three operating segments: 1) U.S. public finance insurance; 2) corporate; and 3) international and structured finance insurance. The Company’s U.S. public finance insurance business is operated through National and its international and structured finance insurance business is operated through MBIA Corp. The following sections provide a description of each of the Company’s reportable operating segments. U.S. Public Finance Insurance The Company’s U.S. public finance insurance portfolio is managed through National. The financial guarantees issued by National provide unconditional and irrevocable guarantees of the payment of the principal of, and interest or other amounts owing on, U.S. public finance insured obligations when due. The obligations are not subject to acceleration, except that National may have the right, at its discretion, to accelerate insured obligations upon default or otherwise. National’s guarantees insure municipal bonds, including tax-exempt and taxable indebtedness of U.S. political subdivisions, as well as utilities, airports, health care institutions, higher educational facilities, housing authorities and other similar agencies and obligations issued by private entities that finance projects that serve a substantial public purpose. Municipal bonds and privately issued bonds used for the financing of public purpose projects are generally supported by taxes, assessments, fees or tariffs related to the use of these projects, lease payments or other similar types of revenue streams. Corporate The Company’s corporate segment consists of general corporate activities, including providing support services to MBIA Inc.’s subsidiaries as well as asset and capital management. Support services are provided by the Company’s service company, MBIA Services, and include, among others, management, legal, accounting, treasury, information technology, and insurance portfolio surveillance, on a fee-for-service basis. Capital management includes activities related to servicing obligations issued by MBIA Inc. and its subsidiaries, MBIA Global Funding, LLC (“GFL”) and MBIA Investment Management Corp. (“IMC”). MBIA Inc. issued debt to finance the operations of the MBIA group. GFL raised funds through the issuance of MTNs with varying maturities, which were in turn guaranteed by MBIA Corp. GFL lent the proceeds of these MTN issuances to MBIA Inc. IMC, along with MBIA Inc., provided customized investment agreements, guaranteed by MBIA Corp., for bond proceeds and other public funds for such purposes as construction, loan origination, escrow and debt service or other reserve fund requirements. The Company has ceased issuing new MTNs and investment agreements and the outstanding liability balances and corresponding asset balances have declined over time as liabilities matured, terminated or were called or repurchased. During 2020, the remaining investment agreements issued by IMC matured, and as of December 31, 2020, there were no outstanding investment agreements issued by IMC. All of the debt within the corporate segment is managed collectively and is serviced by available liquidity. International and Structured Finance Insurance The Company’s international and structured finance insurance segment is principally conducted through MBIA Corp. The financial guarantees issued by MBIA Corp. generally provide unconditional and irrevocable guarantees of the payment of principal of, and interest or other amounts owing on, non-U.S. public finance and global structured finance insured obligations when due, or in the event MBIA Corp. has the right, at its discretion, to accelerate insured obligations upon default or otherwise. MBIA Corp. insures the investment contracts written by MBIA Inc., and if MBIA Inc. were to have insufficient assets to pay amounts due upon maturity or termination, MBIA Corp. would make such payments. MBIA Corp. insures debt obligations of the following affiliates: • MBIA Inc.; • GFL; • IMC; • MZ Funding LLC; and • LaCrosse Financial Products, LLC, a wholly-owned affiliate, to which MBIA Insurance Corporation had written insurance policies guaranteeing the obligations under CDS. Certain policies covered payments potentially due under CDS, including termination payments that may become due in certain circumstances, including the occurrence of certain insolvency or payment defaults under the CDS or derivative contracts by the insured counterparty or by the guarantor. The Company no longer insures new CDS contracts except for potential transactions related to the restructuring of existing exposures. MBIA Corp. insures non-U.S. public finance and global structured finance obligations, including asset-backed obligations. MBIA Corp. has insured sovereign-related and sub-sovereign bonds, utilities, privately issued bonds used for the financing of projects that include toll roads, bridges, airports, public transportation facilities, and other types of infrastructure projects serving a substantial public purpose. Global structured finance and asset-backed obligations typically are securities repayable from expected cash flows generated by a specified pool of assets, such as residential and commercial mortgages, insurance policies, consumer loans, corporate loans and bonds, and aircraft leases. MBIA Corp. has also written policies guaranteeing obligations under certain other derivative contracts, including termination payments that may become due upon certain insolvency or payment defaults of the financial guarantor or the issuer. MBIA Corp. has not written any meaningful amount of business since 2008. Segments Results The following tables provide the Company’s segment results for the three months ended March 31, 2021 and 2020: Three Months Ended March 31, 2021 U.S. International Public and Structured Finance Finance In millions Insurance Corporate Insurance Eliminations Consolidated Revenues (1) $ 23 $ 5 $ 7 $ - $ 35 Net gains (losses) on financial instruments at fair value and foreign exchange (3 ) 55 (1 ) - 51 Revenues of consolidated VIEs - - (14 ) - (14 ) Inter-segment revenues (2) 8 18 4 (30 ) - Total revenues 28 78 (4 ) (30 ) 72 Losses and loss adjustment 109 - (11 ) - 98 Operating 4 21 3 - 28 Interest - 14 27 - 41 Expenses of consolidated VIEs - - 11 - 11 Inter-segment expenses (2) 14 6 10 (30 ) - Total expenses 127 41 40 (30 ) 178 Income (loss) before income taxes $ (99 ) $ 37 $ (44 ) $ - $ (106 ) Identifiable assets $ 3,562 $ 899 $ 3,477 $ (2,563 ) (3) $ 5,375 (1) - Represents the sum of third-party financial guarantee net premiums earned, net investment income, insurance-related fees and reimbursements and other fees. (2) - Represents intercompany premium income and expense and intercompany interest income and expense pertaining to intercompany receivables and payables. (3) - Consists principally of intercompany reinsurance balances. Three Months Ended March 31, 2020 U.S. International Public and Structured Finance Finance In millions Insurance Corporate Insurance Eliminations Consolidated Revenues (1) $ 30 $ 6 $ 7 $ - $ 43 Net gains (losses) on financial instruments at fair value and foreign exchange (18 ) (56 ) 11 - (63 ) Revenues of consolidated VIEs - - 14 - 14 Inter-segment revenues (2) 7 18 4 (29 ) - Total revenues 19 (32 ) 36 (29 ) (6 ) Losses and loss adjustment 48 - 195 - 243 Operating 2 14 4 - 20 Interest - 16 31 - 47 Expenses of consolidated VIEs - - 17 - 17 Inter-segment expenses (2) 14 6 9 (29 ) - Total expenses 64 36 256 (29 ) 327 Income (loss) before income taxes $ (45 ) $ (68 ) $ (220 ) $ - $ (333 ) (1) - Represents the sum of third-party financial guarantee net premiums earned, net investment income, insurance-related fees and reimbursements and other fees. (2) - Represents intercompany premium income and expense and intercompany interest income and expense pertaining to intercompany receivables and payables.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Earnings Per Share	Note 11: Earnings Per Share Earnings per share is calculated using the two-class non-employee Basic earnings per share excludes dilution and is computed by dividing net income (loss) available to common shareholders by the weighted average number of common shares outstanding during the period. Diluted earnings per share reflects the dilutive effect of all unvested restricted stock outstanding during the period that could potentially result in the issuance of common stock. The dilution from unvested restricted stock is calculated by applying the two-class method and using the treasury stock method. The treasury stock method assumes the proceeds from the unrecognized compensation expense from unvested restricted stock will be used to purchase shares of the Company’s common stock at the average market price during the period. If the potentially dilutive securities disclosed in the table below become vested, the transaction would be net share settled resulting in a significantly lower impact to the outstanding share balance in comparison to the total amount of the potentially dilutive securities. During periods of net loss, unvested restricted stock is excluded from the calculation because they would have an antidilutive affect. Therefore, in periods of net loss, the calculation of basic and diluted earnings per share would result in the same value. The following table presents the computation of basic and diluted earnings per share for the three months ended March 31, 2021 and 2020: Three Months In millions except per share amounts 2021 2020 Basic earnings per share: Net income (loss) available to common shareholders $ (106 ) $ (333 ) Basic weighted average shares (1) 49.3 72.1 Net income (loss) per basic common share $ (2.16 ) $ (4.62 ) Diluted earnings per share: Net income (loss) available to common shareholders $ (106 ) $ (333 ) Diluted weighted average shares (1) 49.3 72.1 Net income (loss) per diluted common share $ (2.16 ) $ (4.62 ) Potentially dilutive securities excluded from the calculation of diluted EPS because of antidilutive affect 5.0 4.9 (1) - Includes 0.9 million of participating securities that met the service condition and were eligible to receive nonforfeitable dividends or dividend equivalents for each of the three months ended March 31, 2021 and 2020, respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Accumulated Other Comprehensive Income	Note 12: Accumulated Other Comprehensive Income The following table presents the changes in the components of AOCI for the three months ended March 31, 2021: In millions Unrealized Gains (Losses) on AFS Securities, Net Foreign Currency Translation, Net Instrument-Specific Credit Risk of Liabilities Measured at Fair Value, Net Total Balance, December 31, 2020 $ 176 $ (10 ) $ (51 ) $ 115 Other comprehensive income (loss) before reclassifications (87 ) 1 (5 ) (91 ) Amounts reclassified from AOCI (5 ) - 20 15 Net period other comprehensive income (loss) (92 ) 1 15 (76 ) Balance, March 31, 2021 $ 84 $ (9 ) $ (36 ) $ 39 The following table prese n In millions Amounts Reclassified from AOCI Three Months Ended March 31, Details about AOCI Components 2021 2020 Affected Line Item on the Consolidated Statements of Operations Unrealized gains (losses) on AFS securities: Realized gains (losses) on sale of securities $ 5 $ 3 Net gains (losses) on financial instruments at fair Total unrealized gains (losses) on AFS securities 5 3 Instrument-specific credit risk of liabilities: Settlement of liabilities (20 ) (2 ) Net gains (losses) on financial instruments at fair value and foreign exchange Total reclassifications for the period $ (15 ) $ 1 Net income (loss)

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Commitments and Contingencies	Note 13: Commitments and Contingencies The following commitments and contingencies provide an update of those discussed in “Note 19: Commitments and Contingencies” in the Notes to Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020, and should be read in conjunction with the complete descriptions provided in the aforementioned Form 10-K. Litigation MBIA Insurance Corp. v. Credit Suisse Securities (USA) LLC, et al. On December 14, 2009, MBIA Corp. commenced an action in New York State Supreme Court, New York County, against Credit Suisse. The complaint sought damages for claims in connection with the procurement of financial guarantee insurance on the Home Equity Mortgage Trust Series 2007-2 securitization. On January 30, 2013, MBIA Corp. filed an amended complaint. In November of 2020, following a trial and post-trial briefing, the court overseeing the litigation issued a decision declaring that MBIA Corp. had succeeded in establishing that a majority of the loans in the transaction were ineligible. In January of 2021, the Court issued an order declaring that Credit Suisse was liable to MBIA for approximately $604 million in damages. On February 9, 2021, the parties to the litigation entered into a settlement agreement pursuant to which Credit Suisse paid MBIA Corp. $600 million, and on February 11, 2021, the court entered an order dismissing the case. Tilton v. MBIA Inc., On November 2, 2015, Lynn Tilton and Patriarch Partners XV, LLC filed a complaint in New York State Supreme Court, Westchester County, against MBIA Inc. and MBIA Corp., seeking damages based on allegations of fraudulent inducement and related claims arising from purported promises made in connection with insurance policies issued by MBIA Corp. on certain collateralized loan obligations managed by Ms. Tilton and affiliated Patriarch entities. Plaintiffs filed an amended complaint on January 15, 2016. The parties completed discovery in 2017. In February of 2021, the parties submitted respective cross-motions for summary judgment. Tilton et al. v. MBIA Inc., et al.; Adversary Case No. 19-50390 (KBO) (Bankr. Del.) On October 1, 2019, Lynn Tilton and certain affiliated entities commenced an adversary proceeding in the Zohar Funds Bankruptcy Cases against MBIA Inc., MBIA Corp. and other Zohar Funds creditors seeking the equitable subordination of those creditors’ claims with respect to the Zohar Funds. Plaintiffs claim they are entitled to relief due to inequitable and unfair conduct by defendants. The Company and the other defendants filed their respective motions to dismiss on October 30, 2020 . Zohar CDO 2003-1, Ltd., et al. v. Patriarch Partners, LLC et al., On November 27, 2017, Lynn Tilton and certain affiliated entities commenced a third-party complaint against MBIA Inc., MBIA Insurance Corp. and other Zohar Fund stakeholders seeking damages for alleged breaches of the contracts governing the Zohar Funds and additional alleged legal duties and obligations relating to the Funds. On December 22, 2020, the Company and the other third-party defendants moved to dismiss the third-party complaint. Briefing on those motions to dismiss is complete and the motions are under submission. MBIA Insurance Corp. v. Tilton et al., Adversary Case No. 20-50776 (KBO) (Bankr. Del.) On July 30, 2020, MBIA Corp. commenced an adversary proceeding in the Zohar Funds Bankruptcy Cases against Lynn Tilton and certain affiliated entities seeking damages incurred by MBIA Corp. in connection with insurance policies it issued on senior notes issued by Zohar I and Zohar II. Tilton and her affiliated defendants moved to dismiss the complaint on October 23, 2020. Briefing on the motion is complete and the motion is under submission. Motion of Assured Guaranty Corp., Assured Guaranty Municipal Corp., and National Public Finance Guarantee Corporation for Adequate Protection or, in the Alternative, for Relief from the Automatic Stay On January 16, 2020, National, Ambac and Assured (“Movants”) filed a renewed motion in the PRHTA Title III case for relief from the automatic stay or, in the alternative, adequate protection. The motion seeks leave to file a complaint in Puerto Rico, and argues that the revenues securing the bonds insured by Movants are being improperly diverted away from PRHTA, despite such revenues being the exclusive property of PRHTA and its bondholders. Following a preliminary lift stay hearing held on June 4, 2020, on July 2, 2020, Judge Swain ruled that the Movants had failed to satisfy its burden of presenting a colorable claim that they had a statutory, contractual or equitable lien on HTA. On September 9, 2020, the Court entered a final order denying the HTA lift stay motion, finding that a balancing of factors does not support stay relief. The Movants appealed, and the case was argued before the First Circuit Court of Appeals on February 4, 2021. On March 3, 2021 the First Circuit affirmed Judge Swain’s decision holding that The Financial Oversight and Management Board for Puerto Rico, as representative of The Puerto Rico Electric Power Authority, et al. On July 18, 2017, National, together with other PREPA bondholders, asked the court overseeing PREPA’s Title III bankruptcy proceeding to lift the automatic bankruptcy stay, and permit bondholders to seek appointment of a receiver to oversee PREPA. On September 14, 2017, the court held that PROMESA barred relief from the stay. The bondholders appealed the decision to the First Circuit. On August 8, 2018, the First Circuit issued an order reversing Judge Swain’s decision on jurisdictional grounds and remanding the motion. On October 3, 2018, National, together with other monolines filed an updated motion for relief from the automatic stay to allow Movants to exercise their statutory right to have a receiver appointed at PREPA. The Oversight Board filed a motion to dismiss the receiver motion. These motions have been stayed until five business days following the ruling on the PREPA 9019 Settlement Motion. The PREPA 9019 Settlement Motion has been adjourned until further order of the Court. On May 3, 2019, PREPA, the Oversight Board, the Puerto Rico Fiscal Agency and Financial Advisory Authority (“AAFAF”), the Ad Hoc Group of PREPA bondholders (the “Ad Hoc Group”), and Assured Guaranty Corp. and Assured Guaranty Municipal Corp. (“Assured”) (together, the “RSA Parties”) entered into the RSA. On September 9, 2019 National, Syncora Guarantee Inc. (“Syncora”), and the RSA Parties agreed on an amendment to the RSA pursuant to which National and Syncora joined the RSA. The RSA includes the agreement for resolving PREPA’s restructuring plan issues and arrangements. Pursuant to the RSA, the Oversight Board filed a Rule 9019 motion with the Title III court in May of 2019 seeking approval of the RSA (the “Settlement Motion”). The RSA requires, upon entry of the order approving the Settlement Motion (the “9019 Order”), that Movants will withdraw the Receiver Motion, and the Ad Hoc Group will support such withdrawal. As contemplated by the RSA, on July 1, 2019, the Oversight Board and AAFAF also filed an adversary complaint against the Trustee for the PREPA Bonds, challenging the validity of the liens arising under the Trust Agreement that secure insured obligations of National. The adversary proceeding is stayed until the earlier of (a) 60 days after the Court denies the Settlement Motion, (b) consummation of a Plan, (c) 60 days after the filing by the Oversight Board and AAFAF of a Litigation Notice, or (d) further order of the Court. The hearing for the Settlement Motion has been adjourned until further order of the Court. Cortland Capital Market Services LLC, et al. v. The Financial Oversight and Management Board for Puerto Rico et al., On July 9, 2019, the “Fuel Line Lenders,” parties who extended approximately $700 million to PREPA beginning in 2012 to fund fuel purchases, filed an adversary complaint against the Oversight Board, PREPA, AAFAF, and the Trustee for the PREPA Bonds, alleging that they are entitled to be paid in full before National and other bondholders have any lien on or recourse to PREPA’s assets, including pursuant to the RSA. On September 30, 2019, the Fuel Line Lenders filed an amended complaint which added National, Assured, Syncora, and the Ad Hoc Group as defendants. Defendants moved to dismiss the Fuel Line Lenders’ adversary complaint on November 11, 2019. The Fuel Line Lenders filed their opposition to the motion to dismiss on December 5, 2019. Defendants’ reply in support of the motion to dismiss was filed February 3, 2020. The hearing on the motion to dismiss was adjourned until the Court determines when the 9019 Settlement Motion and related litigation will recommence. The Financial Oversight and Management Board for Puerto Rico, as Representative of the Commonwealth of Puerto Rico, et al. v. the Puerto Rico Public Buildings Authority On December 21, 2018, the Oversight Board and the Official Committee of Unsecured Creditors of all Debtors other than COFINA filed an adversary complaint against the PBA, seeking a declaration that leases purportedly entered into by PBA are in fact disguised financing transactions and that PBA therefore has no right under PROMESA or the Bankruptcy Code to receive post-petition payments from the Title III debtors or administrative claims against the debtors. On January 28, 2019, National filed a motion to intervene in the proceeding. On March 12, 2019, the Court granted National’s intervention motion. On March 19, 2019, National filed an answer to the complaint. On September 27, 2019, the Oversight Board filed a voluntary petition for relief for PBA pursuant to PROMESA, commencing a case under Title III. The complaint has been stayed indefinitely by order of the Court. As part of the GO PSA, National has agreed to stay its participation in this litigation subject to the effective date of the Commonwealth plan of adjustment. The Financial Oversight and Management Board for Puerto Rico, as Representative of the Commonwealth of Puerto Rico, et al. v. National Public Finance Guarantee Corporation, et al On May 2, 2019, the Oversight Board and the Official Committee of Unsecured Creditors of all Title III Debtors (other than COFINA) (the “Committee”) filed lien avoidance adversary complaints against several hundred defendants, including National, challenging the existence, extent, and enforceability of GO bondholders’ liens. After an approximately five-month stay of litigation entered by the Court on July 24, 2019, these adversary proceedings resumed pursuant to an interim schedule entered by the Court in December 2019. On February 5, 2020, National and Assured Guaranty Municipal Corp. filed a motion to dismiss the adversary proceeding. The motion has been stayed indefinitely by order of the Court. As part of the GO PSA, National has agreed to stay its participation in this litigation subject to the effective date of the Commonwealth plan of adjustment. The Financial Oversight and Management Board for Puerto Rico, as Representative of the Commonwealth of Puerto Rico, et al., Case No. 17-03567 LTS (D.P.R. July 17, 2020) (Swain, J.) On July 17, 2020, National, Ambac Assurance Corporation, Assured Guaranty Corp., Assured Guaranty Municipal Corp. and Financial Guaranty Insurance Company sought appointment as trustees under Section 926 of Title 11 of the United States Code to pursue certain claims on behalf of HTA against the Commonwealth of Puerto Rico. On August 11, 2020, Judge Swain denied the motion. The movants appealed to the First Circuit Court of Appeals, and briefing is underway. As part of the GO PSA and HTA PSA, National’s participation in this litigation will be stayed subject to the effective date of the Commonwealth plan of adjustment. National Public Finance Guarantee Corporation et al. v. UBS Financial Services, Inc. et al., On August 8, 2019, National and MBIA Corp. filed suit in the Court of First Instance in San Juan, Puerto Rico against UBS Financial Services, Inc., UBS Securities LLC, Citigroup Global Markets Inc., Goldman Sachs & Co. LLC, J.P. Morgan Securities LLC, Morgan Stanley & Co. LLC, Merrill Lynch, Fenner & Smith Inc., RBC Capital Markets LLC, and Santander Securities LLC, bringing two claims under Puerto Rico law: doctrina de actos propios (the doctrine of one’s own acts) and unilateral declaration of will. These claims concern the insurance by National of bonds issued by the Commonwealth of Puerto Rico and its instrumentalities that were underwritten by these defendants. National alleges that, when the defendants solicited bond insurance, they represented through their acts that they would investigate certain information they provided to National and that they had a reasonable basis to believe that information was true and complete. National further alleges that the defendants did not perform such investigations and that key information was untrue or incomplete. National seeks damages to be proven at trial. On September 9, 2019, Defendants removed National’s claims to federal court in the District of Puerto Rico. National filed its motion to remand the case on October 9, 2019. The Court held a hearing on the remand motion on July 29, 2020, at the end of which it granted National’s motion and remanded the case to the Commonwealth Court of First Instance. On July 31, 2020, National filed an informative motion with the Commonwealth of Puerto Rico Court of First Instance, Superior Court of San Juan, advising that the case has been remanded and requesting the reopening of the case in the Superior Court for further proceedings. On August 2, 2020, the Superior Court recognized the order of Judge Swain remanding the case and acknowledged that proceedings would continue in Commonwealth Court. On September 16, 2020, Defendants filed a motion to dismiss the complaint. National filed its objection to that motion on October 7, 2020, and briefing concluded on November 30, 2020. A decision is pending. Complaint Objecting to Defendants’ Claims and Seeking Related Relief, On January 16, 2020, the Oversight Board filed an adversary complaint against National, Ambac, Assured Guaranty, Assured Guaranty Municipal Corp., Financial Guaranty Insurance Company, Peaje Investments LLC and the Bank of New York Mellon as fiscal agent. The Oversight Board challenges the claims and validity of the liens asserted against the Commonwealth by holders of HTA bonds. The complaint contains 201 counts against the bondholder parties objecting to proofs of claim and security interests asserted regarding the Commonwealth’s retention of certain revenues previously assigned to HTA. This matter is currently stayed but the Court permitted the Oversight Board to file certain limited cross motions on April 28, 2020. The cross motions for summary judgment were filed on July 16, 2020. On September 23, 2020, Judge Swain heard argument on the limited cross motions for summary judgment, which remain pending. On January 20, 2021, Judge Swain issued an order deferring the adjudication of the summary judgment motions so that defendant monolines can seek limited discovery from the Oversight Board on all documents related to the collection and flow of Excise Taxes and pledged revenue into and out of its accounts, among other things. On April 6, 2021, the Oversight Board filed a motion to lift the litigation stay for the limited purpose of filing further summary judgment motions that would dispose of substantially all of the remaining claims challenged in this complaint. The hearing on this motion was held April 28, 2021, and the motion was denied. As part of the GO PSA and HTA PSA, National has agreed to stay its participation in this litigation subject to the effective date of the HTA plan of adjustment. Complaint Objecting to Defendants’ Claims and Seeking Related Relief, On January 16, 2020, the Oversight Board and the Creditors Committee filed an adversary complaint against National and other defendants challenging the claims and validity of the liens asserted against HTA by holders and insurers of HTA bonds. The complaint contains 302 counts challenging the claims and liens asserted against HTA. This matter has been stayed indefinitely by order of the Court. As part of the GO PSA and HTA PSA, National has agreed to stay its participation in this litigation subject to the effective date of the Commonwealth plan of adjustment. For those aforementioned actions in which it is a defendant, the Company is defending against those actions and expects ultimately to prevail on the merits. There is no assurance, however, that the Company will prevail in these actions. Adverse rulings in these actions could have a material adverse effect on the Company’s ability to implement its strategy and on its business, results of operations, cash flows and financial condition. At this stage of the litigation, there has not been a determination as to the amount, if any, of damages. Accordingly, the Company is not able to estimate any amount of loss or range of loss. The Company similarly can provide no assurance that it will be successful in those actions in which it is a plaintiff. There are no other material lawsuits pending or, to the knowledge of the Company, threatened, to which the Company or any of its subsidiaries is a party. Lease Commitments The Company has a lease agreement for its headquarters in Purchase, New York as well an immaterial lease for an office in San Francisco, California, as well as office equipment. The Purchase, New York initial lease term expires in 2030 with the option to terminate the lease in 2025 upon the payment of a termination amount. This lease agreement included an incentive amount to fund certain leasehold improvements, renewal options, escalation clauses and a free rent period. This lease agreement has been classified as an operating lease, and operating rent expense is recognized on a straight-line basis. The following table provides information about the Company’s leases as of March 31, 2021: $ in millions As of Balance Sheet Location Right-of-use $ 19 Other assets Lease liability $ 19 Other liabilitie Weighted average remaining lease term (years) 8.4 Discount rate used for operating leases 7.5% Total future minimum lease payments $ 28

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q S-X 10-K The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at 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. As additional information becomes available or actual amounts become determinable, the recorded estimates are revised and reflected in operating results. The results of operations for the three months ended March 31, 2021 may not be indicative of the results that may be expected for the year ending December 31, 2021. The December 31, 2020 consolidated balance sheet was derived from audited financial statements, but does not include all disclosures required by GAAP for annual periods.
Recently Adopted Accounting Standards	Recently Adopted Accounting Standards The Company has not adopted any new accounting pronouncements that had a material impact on its consolidated financial statements.
New Accounting Pronouncements Not Yet Adopted	Recent Accounting Developments Reference Rate Reform (Topic 848): Scope (ASU 2021-01) and Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting (ASU 2020-04) In January of 2021, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2021-01, “Reference Rate Reform – Scope,” which clarified the scope and application of the original guidance, ASU 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting,” issued in March of 2020. ASU 2020-04 provides optional expedients and exceptions for applying GAAP to contract modifications and hedging relationships that reference London Interbank Offered Rate (“LIBOR”) or other rates that are expected to be discontinued, subject to meeting certain criteria. Both ASU 2020-04 and ASU 2021-01 were effective upon issuance, and the Company may elect to apply the amendments prospectively through December 31, 2022. The Company is evaluating the impact of adopting ASU 2021-01 and 2020-04.

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Summary Of Nonconsolidated VIEs Assets And Liabilities	March 31, 2021 Carrying Value of Assets Carrying Value of Liabilities In millions Maximum Investments Premiums Insurance Loss Unearned Loss and Loss Insurance: Global structured finance: Mortgage-backed residential $ 1,757 $ 80 $ 16 $ 69 $ 13 $ 428 Consumer asset-backed 277 - 1 1 1 13 Corporate asset-backed 628 - 4 333 5 3 Total global structured finance 2,662 80 21 403 19 444 Global public finance 1,415 - 7 - 7 2 Total insurance $ 4,077 $ 80 $ 28 $ 403 $ 26 $ 446 December 31, 2020 Carrying Value of Assets Carrying Value of Liabilities In millions Maximum Investments Premiums Insurance Loss Unearned Loss and Loss Insurance: Global structured finance: Mortgage-backed residential $ 1,835 $ 21 $ 16 $ 90 $ 14 $ 482 Consumer asset-backed 293 - 1 1 1 15 Corporate asset-backed 735 - 5 364 5 - Total global structured finance 2,863 21 22 455 20 497 Global public finance 1,434 - 7 - 7 2 Total insurance $ 4,297 $ 21 $ 29 $ 455 $ 27 $ 499

Loss and Loss Adjustment Expe_2

Loss and Loss Adjustment Expense Reserves (Tables)	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Present Value Of The Probability-Weighted Future Claim Payments And Recoveries	As of March 31, 2021 As of December 31, 2020 In millions Balance Sheet Line Item Balance Sheet Line Item Insurance Loss and (2) Insurance Loss and (2) U.S. Public Finance Insurance $ 1,216 $ 524 $ 1,220 $ 469 International and Structured Finance Insurance: Before VIE eliminations (1) 426 705 1,082 780 VIE eliminations (1) (20 ) (239 ) (625 ) (259 ) Total international and structured finance insurance 406 466 457 521 Total $ 1,622 $ 990 $ 1,677 $ 990 (1) - Includes loan repurchase commitments of $604 million as of December 31, 2020. (2) - Amounts are net of expected recoveries.
Schedule Of Loss And Loss Adjustment Expenses Reserves	In millions Changes in Loss and LAE Reserves for the Three Months Ended March 31, 2021 Gross Loss and Reserves as of December 31, (1) Loss Accretion of Changes in Changes in Changes in Other Gross Loss and Reserves as of (1) $990 $(55) $3 $(11) $57 $- $6 $990 (1) - Includes changes in amount and timing of estimated payments and recoveries.
Schedule Of Insurance Loss Recoverable	Changes in Insurance Loss Recoverable for the Three Months Ended March 31, 2021 In millions Gross Collections Accretion Changes in Changes in (1) Other (2) Gross Insurance loss recoverable $ 1,677 $ (14 ) $ 3 $ (98 ) $ 53 $ 1 $ 1,622 (1) - Includes amounts related to paid claims. (2) - Primarily changes in amount and timing of collections and LAE.
Schedule Of Financial Guarantees And Related Claim Liability	The following table provides information about the financial guarantees and related claim liability included in each of MBIA’s surveillance categories as of March 31, 2021: Surveillance Categories $ in millions Caution Caution Caution High Classified List Total Number of policies 46 16 - 217 279 Number of issues (1) 16 3 - 98 117 Remaining weighted average contract period (in years) 6.3 6.1 - 7.8 7.3 Gross insured contractual payments outstanding: (2) Principal $ 1,390 $ 123 $ - $ 3,251 $ 4,764 Interest 1,933 53 - 1,370 3,356 Total $ 3,323 $ 176 $ - $ 4,621 $ 8,120 Gross Claim Liability (3) $ - $ - $ - $ 1,010 $ 1,010 Less: Gross Potential Recoveries (4) - - - 2,115 2,115 Discount, net (5) - - - (464 ) (464 ) Net claim liability (recoverable) $ - $ - $ - $ (641 ) $ (641 ) Unearned premium revenue $ 9 $ - $ - $ 34 $ 43 Reinsurance recoverable on paid and unpaid losses (6) $ 11 (1) - An “issue” represents the aggregate of financial guarantee policies that share the same revenue source for purposes of making debt service payments on the insured debt. (2) - Represents contractual principal and interest payments due by the issuer of the obligations insured by MBIA. (3) - The gross claim liability with respect to Puerto Rico exposures are net of expected recoveries for policies in a net payable position. (4) - Gross potential recoveries with respect to certain Puerto Rico exposures are net of the claim liability for policies in a net recoverable position. (5) - Represents discount related to Gross Claim Liability and Gross Potential Recoveries. (6) - Included in “Other assets” on the Company’s consolidated balance sheets. The following table provides information about the financial guarantees and related claim liability included in each of MBIA’s surveillance categories as of December 31, 2020: Surveillance Categories $ in millions Caution Caution Caution Classified List Total Number of policies 46 16 - 219 281 Number of issues (1) 16 3 - 100 119 Remaining weighted average contract period (in years) 6.4 6.4 - 7.9 7.4 Gross insured contractual payments outstanding: (2) Principal $ 1,422 $ 123 $ - $ 3,302 $ 4,847 Interest 1,974 54 - 1,441 3,469 Total $ 3,396 $ 177 $ - $ 4,743 $ 8,316 Gross Claim Liability (3) $ - $ - $ - $ 1,088 $ 1,088 Less: Gross Potential Recoveries (4) - - - 1,947 1,947 Discount, net (5) - - - (173 ) (173 ) Net claim liability (recoverable) $ - $ - $ - $ (686 ) $ (686 ) Unearned premium revenue $ 10 $ - $ - $ 35 $ 45 Reinsurance recoverable on paid and unpaid losses (6) $ 11 (1) - An “issue” represents the aggregate of financial guarantee policies that share the same revenue source for purposes of making debt service payments on the insured debt. (2) - Represents contractual principal and interest payments due by the issuer of the obligations insured by MBIA. (3) - The gross claim liability with respect to Puerto Rico exposures are net of expected recoveries for policies in a net payable position. (4) - Gross potential recoveries with respect to certain Puerto Rico exposures are net of the claim liability for policies in a net recoverable position. (5) - Represents discount related to Gross Claim Liability and Gross Potential Recoveries. (6) - Included in “Other assets” on the Company’s consolidated balance sheets.

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Quantitative Information Regarding The Significant Unobservable Inputs For Certain Assets And Liabilities Measured At Fair Value On A Recurring Basis	The following tables provide quantitative information regarding the significant unobservable inputs used by the Company for assets and liabilities measured at fair value on a recurring basis as of March 31, 2021 and December 31, 2020: In millions Fair Value as of 2021 Valuation Techniques Unobservable Input Range (Weighted Average) Assets of consolidated VIEs: Loans receivable at fair value $ 124 Market prices adjusted for financial guarantees provided to VIE obligations Impact of financial guarantee (2) -26% - 84% (20%) (1) Liabilities of consolidated VIEs: Variable interest entity notes 280 Market prices of VIE assets adjusted for financial guarantees provided Impact of financial guarantee 30% - 73% (59%) (1) (1) - Weighted average represents the total MBIA guarantees as a percentage of total instrument fair value. (2) - Negative percentage represents financial guarantee policies in a receivable position. In millions Fair Value as of Valuation Techniques Unobservable Input Range (Weighted Average) Assets of consolidated VIEs: Loans receivable at fair value $ 120 Market prices adjusted for financial guarantees provided to VIE obligations Impact of financial guarantee (2) -28% - 109% (22%) (1) Loan repurchase commitments 604 Discounted cash flow Recovery value (3) Liabilities of consolidated VIEs: Variable interest entity notes 303 Market prices of VIE assets adjusted for financial guarantees provided Impact of financial guarantee 30% - (1) Other derivative liabilities 49 Discounted cash flow Cash flows $49 - (1) - Weighted average represents the total MBIA guarantees as a percentage of total instrument fair value. (2) - Negative percentage represents financial guarantee policies in a receivable position. (3) - Recovery value reflects an estimate of the amount to be awarded to the Company as part of litigation seeking to enforce its contractual rights.
Company's Assets And Liabilities Measured At Fair Value On Recurring Basis	The following tables present the fair value of the Company’s assets (including short-term investments) and liabilities measured and reported at fair value on a recurring basis as of March 31, 2021 and December 31, 2020: Fair Value Measurements at Reporting Date Using In millions Quoted Prices in Significant Significant (Level 3) Balance as of Assets: Fixed-maturity investments: U.S. Treasury and government agency $ 955 $ 99 $ - $ 1,054 State and municipal bonds - 185 - 185 Foreign governments - 17 - 17 Corporate obligations - 984 - 984 Mortgage-backed securities: Residential mortgage-backed agency - 296 - 296 Residential mortgage-backed non-agency - 90 - 90 Commercial mortgage-backed - 14 - 14 Asset-backed securities: Collateralized debt obligations - 125 - 125 Other asset-backed - 193 - 193 Total fixed-maturity investments 955 2,003 - 2,958 Money market securities 30 - - 30 Perpetual debt and equity securities 40 24 - 64 Cash and cash equivalents 116 - - 116 Derivative assets: Non-insured Interest rate derivatives - 1 - 1 Fair Value Measurements at Reporting Date Using In millions Quoted Prices in (Level 1) Significant Significant (Level 3) Balance as of Assets of consolidated VIEs: Corporate obligations - 6 - 6 Mortgage-backed securities: Residential mortgage-backed non-agency - 38 - 38 Commercial mortgage-backed - 16 - 16 Asset-backed securities: Collateralized debt obligations - 8 - 8 Other asset-backed - 8 - 8 Cash 5 - - 5 Loans receivable at fair value: Residential loans receivable - - 124 124 Other assets: Currency derivatives - - 9 9 Other - - 14 14 Total assets $ 1,146 $ 2,104 $ 147 $ 3,397 Liabilities: Medium-term notes $ - $ - $ 105 $ 105 Derivative liabilities: Insured derivatives: Credit derivatives - 1 - 1 Non-insured Interest rate derivatives - 125 - 125 Liabilities of consolidated VIEs: Variable interest entity notes - 45 280 325 Total liabilities $ - $ 171 $ 385 $ 556 Fair Value Measurements at Reporting Date Using In millions Quoted Prices in Significant Significant (Level 3) Balance as of Assets: Fixed-maturity investments: U.S. Treasury and government agency $ 750 $ 105 $ - $ 855 State and municipal bonds - 195 - 195 Foreign governments - 15 - 15 Corporate obligations - 975 - 975 Mortgage-backed securities: Residential mortgage-backed agency - 319 - 319 Residential mortgage-backed non-agency - 32 - 32 Commercial mortgage-backed - 20 - 20 Asset-backed securities: Collateralized debt obligations - 121 - 121 Other asset-backed - 141 - 141 Total fixed-maturity investments 750 1,923 - 2,673 Money market securities 1 - - 1 Perpetual debt and equity securities 37 25 - 62 Cash and cash equivalents 158 - - 158 Derivative assets: Non-insured Interest rate derivatives - 1 - 1 Fair Value Measurements at Reporting Date Using In millions Quoted Prices in (Level 1) Significant Significant (Level 3) Balance as of Assets of consolidated VIEs: Corporate obligations - 6 - 6 Mortgage-backed securities: Residential mortgage-backed non-agency - 40 - 40 Commercial mortgage-backed - 16 - 16 Asset-backed securities: Collateralized debt obligations - 8 - 8 Other asset-backed - 7 - 7 Cash 9 - - 9 Loans receivable at fair value: Residential loans receivable - - 120 120 Loan repurchase commitments - - 604 604 Other assets: Currency derivatives - - 6 6 Other - - 14 14 Total assets $ 955 $ 2,026 $ 744 $ 3,725 Liabilities: Medium-term notes $ - $ - $ 110 $ 110 Derivative liabilities: Insured derivatives: Credit derivatives - 2 - 2 Non-insured Interest rate derivatives - 164 - 164 Other - - 49 49 Liabilities of consolidated VIEs: Variable interest entity notes - 47 303 350 Total liabilities $ - $ 213 $ 462 $ 675
Fair Value Hierarchy Table Presents The Company's Assets And Liabilities Not Recorded At Fair Value On The Company's Consolidated Balance Sheet	Fair Value Measurements at Reporting Date Using In millions Quoted Prices in (Level 1) Significant Significant Fair Value Carry Value Liabilities: Long-term debt $ - $ 736 $ - $ 736 $ 2,258 Medium-term notes - - 395 395 590 Investment agreements - - 353 353 268 Liabilities of consolidated VIEs: Variable interest entity notes - 129 - 129 126 Total liabilities $ - $ 865 $ 748 $ 1,613 $ 3,242 Financial Guarantees: Gross liability (recoverable) $ - $ - $ 874 $ 874 $ (246 ) Ceded recoverable (liability) - - 45 45 (19 ) Fair Value Measurements at Reporting Date Using In millions Quoted Prices in (Level 1) Significant Other Significant Fair Value Carry Value Liabilities: Long-term debt $ - $ 631 $ - $ 631 $ 2,229 Medium-term notes - - 396 396 598 Investment agreements - - 376 376 269 Liabilities of consolidated VIEs: Variable interest entity notes - 276 - 276 273 Total liabilities $ - $ 907 $ 772 $ 1,679 $ 3,369 Financial Guarantees: Gross liability (recoverable) $ - $ - $ 811 $ 811 $ (282 ) Ceded recoverable (liability) - - 45 45 (17 )
Changes In Level 3 Assets Measured At Fair Value On A Recurring Basis	In millions Balance, Total Unrealized (1) Purchases Issuances Settlements Sales Transfers Transfers Ending Change in still held as Change in still held as of (1) Assets: Assets of consolidated VIEs: Loans receivable- residential $ 120 $ 9 $ - $ - $ - $ (5 ) $ - $ - $ - $ 124 $ 8 $ - Loan repurchase commitments 604 (4 ) - - - (600 ) - - - - - - Currency derivatives 6 3 - - - - - - - 9 3 - Other 14 - - - - - - - - 14 - - Total assets $ 744 $ 8 $ - $ - $ - $ (605 ) $ - $ - $ - $ 147 $ 11 $ - In millions Balance, Total Unrealized (1) Purchases Issuances Settlements Sales Transfers Transfers Ending Change in Change in (1) Assets: Other asset-backed $ 1 $ - $ - $ - $ - $ - $ - $ - $ - $ 1 $ - $ - Assets of consolidated VIEs: Loans receivable- 136 (35 ) - - - (3 ) - - - 98 (35 ) - Loan repurchase commitments 486 20 - - - - - - - 506 20 - Currency derivatives 8 10 - - - - - - - 18 10 - Other 18 (3 ) - - - - - - - 15 (3 ) - Total assets $ 649 $ (8 ) $ - $ - $ - $ (3 ) $ - $ - $ - $ 638 $ (8 ) $ - (1) - Reported within the “Unrealized gains (losses) on available-for-sale securities” on MBIA’s Consolidated Statement of Comprehensive Income/Loss.
Changes In Level 3 Liabilities Measured At Fair Value On A Recurring Basis	In millions Balance, Total Unrealized (2) Purchases Issuances Settlements Sales Transfers Transfers Ending Change in March 31, Change in the Period (2) Liabilities: Medium-term notes $ 110 $ (7 ) $ 2 $ - $ - $ - $ - $ - $ - $ 105 $ (7 ) $ 2 Other derivatives 49 - - - - (49 ) - - - - - - Liabilities of consolidated VIEs: VIE notes 303 22 (16 ) - - (29 ) - - - 280 4 3 Total liabilities $ 462 $ 15 $ (14 ) $ - $ - $ (78 ) $ - $ - $ - $ 385 $ (3 ) $ 5 In millions Balance, Total Unrealized (2) Purchases Issuances Settlements Sales Transfers Transfers Ending Change in March 31, Change in (2) Liabilities: Medium-term notes $ 108 $ 2 $ (12 ) $ - $ - $ - $ - $ - $ - $ 98 $ 2 $ (12 ) Credit derivatives 7 1 - - - - - - - 8 1 - Other derivatives 34 3 - - - - - - - 37 3 - Other payable 4 - - - - (4 ) - - - - - - Liabilities of consolidated VIEs: VIE notes 347 (25 ) (36 ) - - (5 ) - - - 281 (28 ) (34 ) Total liabilities $ 500 $ (19 ) $ (48 ) $ - $ - $ (9 ) $ - $ - $ - $ 424 $ (22 ) $ (46 ) (2) - Reported within the “Instrument-specific credit risk of liabilities measured at fair value” on MBIA’s Consolidated Statement of Comprehensive Income/Loss.
Gains And Losses (Realized And Unrealized) Included In Earnings Pertaining To Level 3 Assets And Liabilities	Three Months Ended March 31, 2021 Three Months Ended March 31, 2020 In millions Total Change in Unrealized 2021 Total Change in Unrealized 2020 Revenues: Unrealized gains (losses) on insured derivatives $ - $ - $ (1 ) $ (1 ) Net gains (losses) on financial instruments at fair value and foreign exchange 7 7 (5 ) (5 ) Revenues of consolidated VIEs: Net gains (losses) on financial instruments at fair value and foreign exchange (14 ) 7 17 20 Total $ (7 ) $ 14 $ 11 $ 14
Changes In Fair Value Included In The Company's Consolidated Statements Of Operations	Three Months Ended March 31, In millions 2021 2020 Investments carried at fair value (1) $ 3 $ (20) Fixed-maturity securities held at fair value-VIE (2) 1 (6) Loans receivable at fair value: Residential mortgage loans (2) 9 (35) Loan repurchase commitments (2) (4) 20 Other assets-VIE (2) - (3) Medium-term notes (1) 7 (2) Variable interest entity notes (2) (23) 27 (1) - Reported within “Net gains (losses) of financial instruments at fair value and foreign exchange” on MBIA’s consolidated statements of operations. (2) - Reported within “Net gains (losses) of financial instruments at fair value and foreign exchange-VIE” on MBIA’s consolidated statements of operations.
Difference Between Aggregate Fair Value And The Aggregate Remaining Contractual Principal Balance Outstanding	As of March 31, 2021 As of December 31, 2020 Contractual Contractual Outstanding Fair Outstanding Fair In millions Principal Value Difference Principal Value Difference Loans receivable at fair value: Residential mortgage loans - current $ 85 $ 85 $ - $ 89 $ 89 $ - Residential mortgage loans (90 days or more past due) 144 39 105 147 31 116 Total loans receivable and other instruments at fair value $ 229 $ 124 $ 105 $ 236 $ 120 $ 116 Variable interest entity notes $ 1,080 $ 325 $ 755 $ 1,117 $ 350 $ 767 Medium-term notes $ 118 $ 105 $ 13 $ 122 $ 110 $ 12

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Amortized Cost And Fair Value Of Available-For-Sale And Held-To-Maturity Investment Portfolios	The following tables presents the amortized cost, allowance for credit losses, corresponding gross unrealized gains and losses and fair value for AFS investments in the Company’s consolidated investment portfolio as of March 31, 2021 and December 31, 2020: March 31, 2021 In millions Amortized Allowance Gross Gross Fair AFS Investments Fixed-maturity investments: U.S. Treasury and government agency $ 1,006 $ - $ 47 $ (5 ) $ 1,048 State and municipal bonds 160 - 25 - 185 Foreign governments 13 - - - 13 Corporate obligations 883 - 31 (16 ) 898 Mortgage-backed securities: Residential mortgage-backed agency 285 - 7 (3 ) 289 Residential mortgage-backed non-agency 83 - 4 (3 ) 84 Commercial mortgage-backed 11 - 1 - 12 Asset-backed securities: Collateralized debt obligations 114 - - (1 ) 113 Other asset-backed 173 - - - 173 Total AFS investments $ 2,728 $ - $ 115 $ (28 ) $ 2,815 December 31, 2020 In millions Amortized Allowance Gross Gross Fair AFS Investments Fixed-maturity investments: U.S. Treasury and government agency $ 775 $ - $ 75 $ (1 ) $ 849 State and municipal bonds 162 - 32 - 194 Foreign governments 11 - 1 - 12 Corporate obligations 827 - 64 (1 ) 890 Mortgage-backed securities: Residential mortgage-backed agency 305 - 8 (1 ) 312 Residential mortgage-backed non-agency 22 - 3 - 25 Commercial mortgage-backed 17 - 1 - 18 Asset-backed securities: - Collateralized debt obligations 120 - - (2 ) 118 Other asset-backed 121 - - - 121 Total AFS investments $ 2,360 $ - $ 184 $ (5 ) $ 2,539
Distribution By Contractual Maturity Of Available-For-Sale and Held-To-Maturity Investments	AFS Securities In millions Net Fair Due in one year or less $ 827 $ 829 Due after one year through five years 374 387 Due after five years through ten years 231 248 Due after ten years 630 680 Mortgage-backed and asset-backed 666 671 Total fixed-maturity investments $ 2,728 $ 2,815
Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments	March 31, 2021 Less than 12 Months 12 Months or Longer Total In millions Fair Unrealized Fair Unrealized Fair Unrealized AFS Investments Fixed-maturity investments: U.S. Treasury and government agency $ 125 $ (5 ) $ - $ - $ 125 $ (5 ) State and municipal bonds 4 - - - 4 - Foreign governments 6 - - - 6 - Corporate obligations 278 (15 ) 15 (1 ) 293 (16 ) Mortgage-backed securities: Residential mortgage-backed agency 100 (3 ) - - 100 (3 ) Residential mortgage-backed non-agency 35 (3 ) 1 - 36 (3 ) Commercial mortgage-backed 2 - - - 2 - Asset-backed securities: Collateralized debt obligations 19 - 71 (1 ) 90 (1 ) Other asset-backed 77 - 1 - 78 - Total AFS investments $ 646 $ (26 ) $ 88 $ (2 ) $ 734 $ (28 ) December 31, 2020 Less than 12 Months 12 Months or Longer Total In millions Fair Unrealized Fair Unrealized Fair Unrealized AFS Investments Fixed-maturity investments: U.S. Treasury and government agency $ 99 $ (1 ) $ - $ - $ 99 $ (1 ) Foreign governments 2 - - - 2 - Corporate obligations 103 (1 ) 7 - 110 (1 ) Mortgage-backed securities: Residential mortgage-backed agency 53 (1 ) - - 53 (1 ) Residential mortgage-backed non-agency 2 - 1 - 3 - Commercial mortgage-backed - - 5 - 5 - Asset-backed securities: Collateralized debt obligations 37 - 78 (2 ) 115 (2 ) Other asset-backed 29 - - - 29 - Total AFS investments $ 325 $ (3 ) $ 91 $ (2 ) $ 416 $ (5 )
Distribution Of Securities By Percentage Of Fair Value Below Book Value By More Than 5%	AFS Securities Percentage of Fair Value Below Book Value Number of Book Value Fair Value > 5% to 15% 2 $ 1 $ 1 > 15% to 25% 3 1 1 > 50% 2 - - Total 7 $ 2 $ 2
Securities Held In Unrealized Loss Position And Insured By Financial Guarantor and The Related Insurance Loss Reserve On Company Insured Investments	In millions Fair Unrealized Insurance (1) Mortgage-backed $ 36 $ (3) $ 44 Corporate obligations 85 (10) - Total $ 121 $ (13) $ 44 (1) - Insurance loss reserve estimates are based on the proportion of par value owned to the total amount of par value insured and are discounted using a discount rate equal to the risk-free rate applicable to the currency and weighted average remaining life of the insurance contract and may differ from the fair value.
Summary of Allowance for Credit Losses on HTM Investments	Three Months Ended March 31, 2020 In millions Balance (1) Current Initial Write-Offs Recoveries Balance HTM Investments Assets of consolidated VIEs: Corporate obligations $ 37 $ 9 $ - $ - $ - $ 46 Total Allowance on HTM investments $ 37 $ 9 $ - $ - $ - $ 46 (1) - Represents transition adjustment upon adoption of ASU 2016-13.
Gross Realized Gains and Losses From Sales Of Available-For-Sale Securities	Three Months Ended In millions 2021 2020 Proceeds from sales $ 178 $ 279 Gross realized gains $ 4 $ 11 Gross realized losses $ (5 ) $ (8 )
Portion Of Unrealized Gains Losses Recognized On Equity Investments	Three In millions 2021 2020 Net gains and (losses) recognized during the period on equity securities $ 2 $ (13 ) Less: Net gains and (losses) recognized during the period on equity securities sold during the period - - Unrealized gains and (losses) recognized during the period on equity securities still held at the reporting date $ 2 $ (13 )

Derivative Instruments (Tables)

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Credit Derivatives Sold	$ in millions As of March 31, 2021 Notional Value Credit Derivatives Sold Weighted AAA AA A BBB Below Total Fair Insured swaps 13.8 Years $ - $ 56 $ 1,311 $ 358 $ - $ 1,725 $ (1 ) Total notional $ - $ 56 $ 1,311 $ 358 $ - $ 1,725 Total fair value $ - $ - $ - $ (1 ) $ - $ (1 ) $ in millions As of December 31, 2020 Notional Value Credit Derivatives Sold Weighted AAA AA A BBB Below Total Fair Insured swaps 13.9 Years $ - $ 58 $ 1,327 $ 358 $ - $ 1,743 $ (2 ) Total notional $ - $ 58 $ 1,327 $ 358 $ - $ 1,743 Total fair value $ - $ - $ (1 ) $ (1 ) $ - $ (2 )
Total Fair Value Of Company's Derivative Assets And Liabilities By Instrument And Balance Sheet Location, Before Counterparty Netting	The following table presents the total fair value of the Company’s derivative assets and liabilities by instrument and balance sheet location, before counterparty netting, as of March 31, 2021: In millions Derivative Assets (1) Derivative Liabilities (1) Derivative Instruments Notional Balance Sheet Fair Balance Sheet Fair Not designated as hedging instruments: Insured swaps $ 1,725 Other assets $ - Derivative liabilities $ (1 ) Interest rate swaps 429 Other assets 1 Derivative liabilities (125 ) Interest rate swaps-embedded 241 Medium-term notes - Medium-term notes (10 ) Currency swaps-VIE 52 Other assets-VIE 9 Derivative liabilities-VIE - Total non-designated $ 2,447 $ 10 $ (136 ) ( In accordance with the accounting guidance for derivative instruments and hedging activities, the balance sheet location of the Company’s embedded derivative instruments is determined by the location of the related host contract. The following table presents the total fair value of the Company’s derivative assets and liabilities by instrument and balance sheet location, before counterparty netting, as of December 31, 2020: In millions Derivative Assets (1) Derivative Liabilities (1) Derivative Instruments Notional Balance Sheet Fair Balance Sheet Fair Not designated as hedging instruments: Insured swaps $ 1,743 Other assets $ - Derivative liabilities $ (2 ) Interest rate swaps 437 Other assets 1 Derivative liabilities (164 ) Interest rate swaps-embedded 252 Medium-term notes - Medium-term notes (10 ) Currency swaps-VIE 53 Other assets-VIE 6 Derivative liabilities-VIE - All other 49 Other assets - Derivative liabilities (49 ) Total non-designated $ 2,534 $ 7 $ (225 ) (1) - In accordance with the accounting guidance for derivative instruments and hedging activities, the balance sheet location of the Company’s embedded derivative instruments is determined by the location of the related host contract.
Effect Of Derivative Instruments On Consolidated Statements Of Operations	The following table presents the effect of derivative instruments on the consolidated statements of operations for the three months ended March 31, 2021 and 2020: In millions Derivatives Not Designated as Three Months Ended March 31, Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivative 2021 2020 Insured credit default swaps Unrealized gains (losses) on insured derivatives $ - $ (1 ) Interest rate swaps Net gains (losses) on financial instruments at fair value and foreign exchange 35 (56 ) Currency swaps-VIE Net gains (losses) on financial instruments at fair value and foreign exchange-VIE 2 10 All other Net gains (losses) on financial instruments at fair value and foreign exchange - (3 ) Total $ 37 $ (50 )

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income (loss) from operations before provision (benefit) for income taxes	The Company’s income taxes and the related effective tax rates for the three months ended March 31, 2021 and 2020 are as follows: Three Months Ended March 31, In millions 2021 2020 Income (loss) before income taxes $ (106 ) $ (333 ) Provision (benefit) for income taxes $ - $ - Effective tax rate 0.0% 0.0%

Business Segments (Tables)

Business Segments (Tables)	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Summary of company's segment results	The following tables provide the Company’s segment results for the three months ended March 31, 2021 and 2020: Three Months Ended March 31, 2021 U.S. International Public and Structured Finance Finance In millions Insurance Corporate Insurance Eliminations Consolidated Revenues (1) $ 23 $ 5 $ 7 $ - $ 35 Net gains (losses) on financial instruments at fair value and foreign exchange (3 ) 55 (1 ) - 51 Revenues of consolidated VIEs - - (14 ) - (14 ) Inter-segment revenues (2) 8 18 4 (30 ) - Total revenues 28 78 (4 ) (30 ) 72 Losses and loss adjustment 109 - (11 ) - 98 Operating 4 21 3 - 28 Interest - 14 27 - 41 Expenses of consolidated VIEs - - 11 - 11 Inter-segment expenses (2) 14 6 10 (30 ) - Total expenses 127 41 40 (30 ) 178 Income (loss) before income taxes $ (99 ) $ 37 $ (44 ) $ - $ (106 ) Identifiable assets $ 3,562 $ 899 $ 3,477 $ (2,563 ) (3) $ 5,375 (1) - Represents the sum of third-party financial guarantee net premiums earned, net investment income, insurance-related fees and reimbursements and other fees. (2) - Represents intercompany premium income and expense and intercompany interest income and expense pertaining to intercompany receivables and payables. (3) - Consists principally of intercompany reinsurance balances. Three Months Ended March 31, 2020 U.S. International Public and Structured Finance Finance In millions Insurance Corporate Insurance Eliminations Consolidated Revenues (1) $ 30 $ 6 $ 7 $ - $ 43 Net gains (losses) on financial instruments at fair value and foreign exchange (18 ) (56 ) 11 - (63 ) Revenues of consolidated VIEs - - 14 - 14 Inter-segment revenues (2) 7 18 4 (29 ) - Total revenues 19 (32 ) 36 (29 ) (6 ) Losses and loss adjustment 48 - 195 - 243 Operating 2 14 4 - 20 Interest - 16 31 - 47 Expenses of consolidated VIEs - - 17 - 17 Inter-segment expenses (2) 14 6 9 (29 ) - Total expenses 64 36 256 (29 ) 327 Income (loss) before income taxes $ (45 ) $ (68 ) $ (220 ) $ - $ (333 ) (1) - Represents the sum of third-party financial guarantee net premiums earned, net investment income, insurance-related fees and reimbursements and other fees. (2) - Represents intercompany premium income and expense and intercompany interest income and expense pertaining to intercompany receivables and payables.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Schedule Of Basic And Diluted Earnings Per Share	The following table presents the computation of basic and diluted earnings per share for the three months ended March 31, 2021 and 2020: Three Months In millions except per share amounts 2021 2020 Basic earnings per share: Net income (loss) available to common shareholders $ (106 ) $ (333 ) Basic weighted average shares (1) 49.3 72.1 Net income (loss) per basic common share $ (2.16 ) $ (4.62 ) Diluted earnings per share: Net income (loss) available to common shareholders $ (106 ) $ (333 ) Diluted weighted average shares (1) 49.3 72.1 Net income (loss) per diluted common share $ (2.16 ) $ (4.62 ) Potentially dilutive securities excluded from the calculation of diluted EPS because of antidilutive affect 5.0 4.9 (1) - Includes 0.9 million of participating securities that met the service condition and were eligible to receive nonforfeitable dividends or dividend equivalents for each of the three months ended March 31, 2021 and 2020, respectively.

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Changes In The Components Of AOCI	The following table presents the changes in the components of AOCI for the three months ended March 31, 2021: In millions Unrealized Gains (Losses) on AFS Securities, Net Foreign Currency Translation, Net Instrument-Specific Credit Risk of Liabilities Measured at Fair Value, Net Total Balance, December 31, 2020 $ 176 $ (10 ) $ (51 ) $ 115 Other comprehensive income (loss) before reclassifications (87 ) 1 (5 ) (91 ) Amounts reclassified from AOCI (5 ) - 20 15 Net period other comprehensive income (loss) (92 ) 1 15 (76 ) Balance, March 31, 2021 $ 84 $ (9 ) $ (36 ) $ 39
Reclassifications From AOCI	The following table prese n In millions Amounts Reclassified from AOCI Three Months Ended March 31, Details about AOCI Components 2021 2020 Affected Line Item on the Consolidated Statements of Operations Unrealized gains (losses) on AFS securities: Realized gains (losses) on sale of securities $ 5 $ 3 Net gains (losses) on financial instruments at fair Total unrealized gains (losses) on AFS securities 5 3 Instrument-specific credit risk of liabilities: Settlement of liabilities (20 ) (2 ) Net gains (losses) on financial instruments at fair value and foreign exchange Total reclassifications for the period $ (15 ) $ 1 Net income (loss)

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2021
Text Block [Abstract]
Operating Leases Of Lessee Disclosure	$ in millions As of Balance Sheet Location Right-of-use $ 19 Other assets Lease liability $ 19 Other liabilitie Weighted average remaining lease term (years) 8.4 Discount rate used for operating leases 7.5% Total future minimum lease payments $ 28

Business Developments And Ris_2

Business Developments And Risks And Uncertainties (Narrative) (Detail) $ in Millions	Feb. 10, 2021USD ($)	Jan. 01, 2021USD ($)	Mar. 31, 2021USD ($)segments
Business Acquisition [Line Items]
Number of operating segments | segments			3
Federal legislation passed to combat the economic impact			$ 2,700,000
New relief plan proposed to stabilize the financial system			1,900,000
Aid allocated to state and local governments			350,000
Credit Suisse [Member]
Business Acquisition [Line Items]
Damages Paid Value	$ 600
Damages Sought Value			604
Puerto Rico [Member]
Business Acquisition [Line Items]
Claims payments		$ 51
Outstanding bonds			2,900
MBIA Corp Financing Facility [Member]
Business Acquisition [Line Items]
Payment for Debt Extinguishment or Debt Prepayment Cost			$ 150
Debt Instrument, Interest Rate, Stated Percentage			12.00%
Debt Instrument, Maturity Date			Jan. 20, 2022
Long-term Debt			$ 127

Variable Interest Entities (Nar

Variable Interest Entities (Narrative) (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)	Mar. 31, 2020	Dec. 31, 2020USD ($)
Variable Interest Entity [Line Items]
Carrying amounts of assets	$ 5,375		$ 5,751
Carrying amounts of liabilities	5,403		5,602
Variable Interest Entity Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Carrying amounts of assets	228		830
Carrying amounts of liabilities	$ 474		$ 623
Variable Interest Entity Primary Beneficiary [Member] | US Public Finance [Member]
Variable Interest Entity [Line Items]
Number of variable interest entities deconsolidated		7
Number of variable interest entities consolidated		0
Variable Interest Entity Primary Beneficiary [Member] | Structured Finance And International Insurance [Member]
Variable Interest Entity [Line Items]
Number of variable interest entities deconsolidated	0	1

Variable Interest Entities (Sum

Variable Interest Entities (Summary Of Nonconsolidated VIEs Assets And Liabilities) (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	$ 4,077	$ 4,297
Carrying Value of VIE Assets	5,375	5,751
Carrying Value of VIE Liabilities	5,403	5,602
Investments [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	80	21
Premiums Receivable [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	28	29
Insurance Loss Recoverable [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	403	455
Unearned Premium Revenue [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Liabilities	26	27
Loss And Loss Adjustment Expense Reserves Member [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Liabilities	446	499
Global Structured Finance [Member]
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	2,662	2,863
Global Structured Finance [Member] | Investments [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	80	21
Global Structured Finance [Member] | Premiums Receivable [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	21	22
Global Structured Finance [Member] | Insurance Loss Recoverable [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	403	455
Global Structured Finance [Member] | Unearned Premium Revenue [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Liabilities	19	20
Global Structured Finance [Member] | Loss And Loss Adjustment Expense Reserves Member [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Liabilities	444	497
Global Structured Finance [Member] | Residential Mortgage Backed Securities [Member]
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	1,757	1,835
Global Structured Finance [Member] | Residential Mortgage Backed Securities [Member] | Investments [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	80	21
Global Structured Finance [Member] | Residential Mortgage Backed Securities [Member] | Premiums Receivable [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	16	16
Global Structured Finance [Member] | Residential Mortgage Backed Securities [Member] | Insurance Loss Recoverable [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	69	90
Global Structured Finance [Member] | Residential Mortgage Backed Securities [Member] | Unearned Premium Revenue [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Liabilities	13	14
Global Structured Finance [Member] | Residential Mortgage Backed Securities [Member] | Loss And Loss Adjustment Expense Reserves Member [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Liabilities	428	482
Global Structured Finance [Member] | Consumer Asset Backed [Member]
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	277	293
Global Structured Finance [Member] | Consumer Asset Backed [Member] | Investments [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	0	0
Global Structured Finance [Member] | Consumer Asset Backed [Member] | Premiums Receivable [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	1	1
Global Structured Finance [Member] | Consumer Asset Backed [Member] | Insurance Loss Recoverable [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	1	1
Global Structured Finance [Member] | Consumer Asset Backed [Member] | Unearned Premium Revenue [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Liabilities	1	1
Global Structured Finance [Member] | Consumer Asset Backed [Member] | Loss And Loss Adjustment Expense Reserves Member [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Liabilities	13	15
Global Structured Finance [Member] | Corporate Asset Backed [Member]
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	628	735
Global Structured Finance [Member] | Corporate Asset Backed [Member] | Investments [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	0	0
Global Structured Finance [Member] | Corporate Asset Backed [Member] | Premiums Receivable [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	4	5
Global Structured Finance [Member] | Corporate Asset Backed [Member] | Insurance Loss Recoverable [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	333	364
Global Structured Finance [Member] | Corporate Asset Backed [Member] | Unearned Premium Revenue [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Liabilities	5	5
Global Structured Finance [Member] | Corporate Asset Backed [Member] | Loss And Loss Adjustment Expense Reserves Member [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Liabilities	3	0
Global Public Finance [Member]
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	1,415	1,434
Global Public Finance [Member] | Investments [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	0	0
Global Public Finance [Member] | Premiums Receivable [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	7	7
Global Public Finance [Member] | Insurance Loss Recoverable [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Assets	0	0
Global Public Finance [Member] | Unearned Premium Revenue [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Liabilities	7	7
Global Public Finance [Member] | Loss And Loss Adjustment Expense Reserves Member [Member]
Variable Interest Entity [Line Items]
Carrying Value of VIE Liabilities	$ 2	$ 2

Loss And Loss Adjustment Expe_3

Loss And Loss Adjustment Expense Reserves (Loss And LAE Activity) (Narrative) (Detail) - USD ($) $ in Millions	Feb. 10, 2021	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Loss And Loss Adjustment Expense Reserves [Line Items]
Weighted average risk-free rate used to discount claim liability		1.56%
Credit Suisse [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Damages Sought Value		$ 604
Damages Paid Value	$ 600
Lae [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Losses and loss adjustment		12	$ 9
Loss and loss adjustment expense reserves		$ 39		$ 30
Changes in Loss and LAE Reserves		one-year

Loss And Loss Adjustment Expe_4

Loss And Loss Adjustment Expense Reserves (Schedule Of Losses And Loss Adjustment Expenses Reserves and Recoveries) (Detail) - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Loss And Lae Reserves [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Loss and loss adjustment expense reserves	[1],[2]	$ 990	$ 990
Insurance Loss Recoverable [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance Loss Recoverable		1,622	1,677
Non Variable Interest Entity [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance Loss Recoverable		1,622	1,677
Loss and loss adjustment expense reserves		990	990
US Public Finance [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance Loss Recoverable		1,216	1,220
Loss and loss adjustment expense reserves	[1]	524	469
International And Structured Finance Insurance [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance Loss Recoverable	[3]	426	1,082
Loss and loss adjustment expense reserves	[1],[3]	705	780
International And Structured Finance Insurance [Member] | Non Variable Interest Entity [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance Loss Recoverable		406	457
Loss and loss adjustment expense reserves	[1]	466	521
Consolidation Elimination [Member] | International And Structured Finance Insurance [Member] | Variable Interest Entity Primary Beneficiary [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Insurance Loss Recoverable	[3]	(20)	(625)
Loss and loss adjustment expense reserves	[1],[3]	$ (239)	$ (259)
[1]	Amounts are net of expected recoveries.
[2]	Includes changes in amount and timing of estimated payments and recoveries.
[3]	Includes loan repurchase commitments of $604 million as of December 31, 2020.

Loss And Loss Adjustment Expe_5

Loss And Loss Adjustment Expense Reserves (Schedule Of Loss And Loss Adjustment Expenses Reserves) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Loss And Loss Adjustment Expense Reserves [Line Items]
Changes in unearned premium revenue		$ 19	$ 19
Loss And Lae Reserves [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Gross loss and LAE reserve, beginning balance	[1],[2]	990
Loss payments for cases		(55)
Accretion of claim liability discount		3
Changes in discount rates		(11)
Changes in assumptions		57
Changes in unearned premium revenue		0
Other		6
Gross loss and LAE reserve, ending balance	[1],[2]	$ 990
[1]	Amounts are net of expected recoveries.
[2]	Includes changes in amount and timing of estimated payments and recoveries.

Loss And Loss Adjustment Expe_6

Loss And Loss Adjustment Expense Reserves (Schedule Of Insurance Loss Recoverable) (Detail) - Insurance Loss Recoverable [Member] $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)
Roll forward of Insurance Loss Recoverable [Line Items]
Gross Reserve beginning balance, Insurance loss recoverable	$ 1,677
Collections for Cases	(14)
Accretion of Recoveries	3
Changes in Discount Rates	(98)
Changes in Assumptions	53	[1]
Other	1	[2]
Gross Reserve ending balance, Insurance loss recoverable	$ 1,622
[1]	Includes amounts related to paid claims and LAE.
[2]	Primarily changes in amount and timing of collections.

Loss And Loss Adjustment Expe_7

Loss And Loss Adjustment Expense Reserves (Schedule Of Financial Guarantees And Related Claim Liability) (Detail) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2021USD ($)issuepolicy	Dec. 31, 2020USD ($)issuepolicy
Loss And Loss Adjustment Expense Reserves [Line Items]
Number of policies | policy		279	281
Number of issues | issue	[1]	117	119
Remaining weighted average contract period (in years)		7 years 3 months 18 days	7 years 4 months 24 days
Principal	[2]	$ 4,764	$ 4,847
Interest	[2]	3,356	3,469
Total	[2]	8,120	8,316
Gross claim liability	[3]	1,010	1,088
Less: Gross potential recoveries	[4]	2,115	1,947
Discount, net	[5]	(464)	(173)
Net claim liability (recoverable)		(641)	(686)
Unearned premium revenue		43	45
Reinsurance recoverables on paid and unpaid losses	[6]	$ 11	$ 11
Caution List Low [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Number of policies | policy		46	46
Number of issues | issue	[1]	16	16
Remaining weighted average contract period (in years)		6 years 3 months 18 days	6 years 4 months 24 days
Principal	[2]	$ 1,390	$ 1,422
Interest	[2]	1,933	1,974
Total	[2]	3,323	3,396
Gross claim liability	[3]	0	0
Less: Gross potential recoveries	[4]	0	0
Discount, net	[5]	0	0
Net claim liability (recoverable)		0	0
Unearned premium revenue		$ 9	$ 10
Caution List Medium [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Number of policies | policy		16	16
Number of issues | issue	[1]	3	3
Remaining weighted average contract period (in years)		6 years 1 month 6 days	6 years 4 months 24 days
Principal	[2]	$ 123	$ 123
Interest	[2]	53	54
Total	[2]	176	177
Gross claim liability	[3]	0	0
Less: Gross potential recoveries	[4]	0	0
Discount, net	[5]	0	0
Net claim liability (recoverable)		0	0
Unearned premium revenue		$ 0	$ 0
Caution List High [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Number of policies | policy		0	0
Number of issues | issue	[1]	0	0
Principal	[2]	$ 0	$ 0
Interest	[2]	0	0
Total	[2]	0	0
Gross claim liability	[3]	0	0
Less: Gross potential recoveries	[4]	0	0
Discount, net	[5]	0	0
Net claim liability (recoverable)		0	0
Unearned premium revenue		$ 0	$ 0
Classified List [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Number of policies | policy		217	219
Number of issues | issue	[1]	98	100
Remaining weighted average contract period (in years)		7 years 9 months 18 days	7 years 10 months 24 days
Principal	[2]	$ 3,251	$ 3,302
Interest	[2]	1,370	1,441
Total	[2]	4,621	4,743
Gross claim liability	[3]	1,010	1,088
Less: Gross potential recoveries	[4]	2,115	1,947
Discount, net	[5]	(464)	(173)
Net claim liability (recoverable)		(641)	(686)
Unearned premium revenue		$ 34	$ 35
[1]	An “issue” represents the aggregate of financial guarantee policies that share the same revenue source for purposes of making debt service payments on the insured debt.
[2]	Represents contractual principal and interest payments due by the issuer of the obligations insured by MBIA.
[3]	The gross claim liability with respect to Puerto Rico exposures are net of expected recoveries for policies in a net payable position.
[4]	Gross potential recoveries with respect to certain Puerto Rico exposures are net of the claim liability for policies in a net recoverable position.
[5]	Represents discount related to Gross Claim Liability and Gross Potential Recoveries.
[6]	Included in “Other assets” on the Company’s consolidated balance sheets.

Fair Value Of Financial Instr_3

Fair Value Of Financial Instruments (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Percentage of level 3 assets at fair value in total assets measured at fair value value	4.00%		20.00%
Percentage of level 3 liabilities at fair value in total liabilities measured at fair value	69.00%		68.00%
Cumulative changes in instrument-specific credit risk of liabilities elected under the fair value option	$ (39)		$ (115)
Loan Repurchase Commitments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Payments for Litigation Settlements	600
Instrument-specific credit risk of liabilities measured at fair value, net [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cumulative changes in instrument-specific credit risk of liabilities elected under the fair value option	36		$ 51
Loss on instrument-specific credit risk recognized in earnings	$ 20	$ 2

Fair Value Of Financial Instr_4

Fair Value Of Financial Instruments (Quantitative Information Regarding The Significant Unobservable Inputs For Certain Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Detail) - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Cash Flows [Member] | Discounted cash flow [Member] | Other Derivatives Liabilities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value, liabilities			$ 49
Minimum [Member] | Cash Flows [Member] | Discounted cash flow [Member] | Other Derivatives Liabilities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Range dollars			49
Maximum [Member] | Cash Flows [Member] | Discounted cash flow [Member] | Other Derivatives Liabilities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Range dollars			49
Weighted Average [Member] | Cash Flows [Member] | Discounted cash flow [Member] | Other Derivatives Liabilities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Range dollars			49
Variable Interest Entity Primary Beneficiary [Member] | Variable Interest Entity Notes [Member] | Impact Of Financial Guarantee [Member] | Quoted market prices of VIE assets adjusted for financial guarantees provided [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value, liabilities		$ 280	303
Variable Interest Entity Primary Beneficiary [Member] | Loans Receivable and Other Instruments at Fair Value [Member] | Impact Of Financial Guarantee [Member] | Market Prices Adjusted For Financial Guarantees Provided To VIE Obligations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, assets	[1]	$ 124	120
Variable Interest Entity Primary Beneficiary [Member] | Loan Repurchase Commitments [Member] | Recovery Rates And Breach Rates [Member] | Discounted cash flow [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, assets	[2]		$ 604
Variable Interest Entity Primary Beneficiary [Member] | Minimum [Member] | Variable Interest Entity Notes [Member] | Impact Of Financial Guarantee [Member] | Market Prices Adjusted For Financial Guarantees Provided To VIE Obligations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Range percentage	[3]	30.00%	30.00%
Variable Interest Entity Primary Beneficiary [Member] | Minimum [Member] | Loans Receivable and Other Instruments at Fair Value [Member] | Impact Of Financial Guarantee [Member] | Market Prices Adjusted For Financial Guarantees Provided To VIE Obligations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Range percentage	[3]	(26.00%)	(28.00%)
Variable Interest Entity Primary Beneficiary [Member] | Maximum [Member] | Variable Interest Entity Notes [Member] | Impact Of Financial Guarantee [Member] | Market Prices Adjusted For Financial Guarantees Provided To VIE Obligations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Range percentage	[3]	73.00%	73.00%
Variable Interest Entity Primary Beneficiary [Member] | Maximum [Member] | Loans Receivable and Other Instruments at Fair Value [Member] | Impact Of Financial Guarantee [Member] | Market Prices Adjusted For Financial Guarantees Provided To VIE Obligations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Range percentage	[3]	84.00%	109.00%
Variable Interest Entity Primary Beneficiary [Member] | Weighted Average [Member] | Variable Interest Entity Notes [Member] | Impact Of Financial Guarantee [Member] | Market Prices Adjusted For Financial Guarantees Provided To VIE Obligations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Range percentage	[3]	59.00%	57.00%
Variable Interest Entity Primary Beneficiary [Member] | Weighted Average [Member] | Loans Receivable and Other Instruments at Fair Value [Member] | Impact Of Financial Guarantee [Member] | Market Prices Adjusted For Financial Guarantees Provided To VIE Obligations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Range percentage	[3]	20.00%	22.00%
[1]	Negative percentage represents financial guarantee policies in a receivable position.Negative percentage represents financial guarantee policies in a receivable position.
[2]	Recovery value reflects an estimate of the amount to be awarded to the Company as part of litigation seeking to enforce its contractual rights.
[3]	Weighted average represents the total MBIA guarantees as a percentage of total instrument fair value.

Fair Value Of Financial Instr_5

Fair Value Of Financial Instruments (Company's Assets And Liabilities Measured At Fair Value On Recurring Basis) (Detail) - Fair Value Measurements Recurring [Member] - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	$ 3,397	$ 3,725
Fair value financial liabilities measured on recurring basis	556	675
Money Market Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	30	1
Medium-term Notes [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	105	110
Perpetual Debt And Equity Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	64	62
Cash and Cash Equivalents [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	116	158
Fixed Maturities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	2,958	2,673
Fixed Maturities [Member] | U S Treasury And Government [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,054	855
Fixed Maturities [Member] | State and municipal bonds [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	185	195
Fixed Maturities [Member] | Foreign Government Debt [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	17	15
Fixed Maturities [Member] | Corporate Obligations [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	984	975
Fixed Maturities [Member] | Residential Mortgage Backed Agency [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	296	319
Fixed Maturities [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	90	32
Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	14	20
Fixed Maturities [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	125	121
Fixed Maturities [Member] | Other Asset Backed [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	193	141
Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1	1
Assets Of Consolidated V I Es [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Loan Repurchase Commitments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis		604
Assets Of Consolidated V I Es [Member] | Corporate Obligations [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	6	6
Assets Of Consolidated V I Es [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	38	40
Assets Of Consolidated V I Es [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	16	16
Assets Of Consolidated V I Es [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	8	8
Assets Of Consolidated V I Es [Member] | Other Asset Backed [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	8	7
Assets Of Consolidated V I Es [Member] | Loans Receivable and Other Instruments At Fair Value [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Residential Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	124	120
Assets Of Consolidated V I Es [Member] | Currency Derivatives [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	9	6
Assets Of Consolidated V I Es [Member] | Cash and Cash Equivalents [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	5	9
Assets Of Consolidated V I Es [Member] | Other [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	14	14
Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	1	2
Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	125	164
Derivative Liabilities [Member] | Other Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis		49
Liabilities Of Consolidated Vies [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	325	350
Fair Value Inputs Level 1 [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,146	955
Fair value financial liabilities measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Money Market Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	30	1
Fair Value Inputs Level 1 [Member] | Medium-term Notes [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Perpetual Debt And Equity Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	40	37
Fair Value Inputs Level 1 [Member] | Cash and Cash Equivalents [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	116	158
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	955	750
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | U S Treasury And Government [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	955	750
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | State and municipal bonds [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Foreign Government Debt [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Corporate Obligations [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Residential Mortgage Backed Agency [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Other Asset Backed [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Loan Repurchase Commitments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis		0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Corporate Obligations [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Other Asset Backed [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Loans Receivable and Other Instruments At Fair Value [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Residential Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Currency Derivatives [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Cash and Cash Equivalents [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	5	9
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Other [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	0	0
Fair Value Inputs Level 1 [Member] | Derivative Liabilities [Member] | Other Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis		0
Fair Value Inputs Level 1 [Member] | Liabilities Of Consolidated Vies [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	0	0
Fair Value Inputs Level 2 [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	2,104	2,026
Fair value financial liabilities measured on recurring basis	171	213
Fair Value Inputs Level 2 [Member] | Money Market Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 2 [Member] | Medium-term Notes [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	0	0
Fair Value Inputs Level 2 [Member] | Perpetual Debt And Equity Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	24	25
Fair Value Inputs Level 2 [Member] | Cash and Cash Equivalents [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	2,003	1,923
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | U S Treasury And Government [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	99	105
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | State and municipal bonds [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	185	195
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Foreign Government Debt [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	17	15
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Corporate Obligations [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	984	975
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Residential Mortgage Backed Agency [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	296	319
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	90	32
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	14	20
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	125	121
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Other Asset Backed [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	193	141
Fair Value Inputs Level 2 [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1	1
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Loan Repurchase Commitments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis		0
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Corporate Obligations [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	6	6
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	38	40
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	16	16
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	8	8
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Other Asset Backed [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	8	7
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Loans Receivable and Other Instruments At Fair Value [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Residential Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Currency Derivatives [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Cash and Cash Equivalents [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 2 [Member] | Assets Of Consolidated V I Es [Member] | Other [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 2 [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	1	2
Fair Value Inputs Level 2 [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	125	164
Fair Value Inputs Level 2 [Member] | Derivative Liabilities [Member] | Other Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis		0
Fair Value Inputs Level 2 [Member] | Liabilities Of Consolidated Vies [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	45	47
Fair Value Inputs Level 3 [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	147	744
Fair value financial liabilities measured on recurring basis	385	462
Fair Value Inputs Level 3 [Member] | Money Market Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Medium-term Notes [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	105	110
Fair Value Inputs Level 3 [Member] | Perpetual Debt And Equity Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Cash and Cash Equivalents [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | U S Treasury And Government [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | State and municipal bonds [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Foreign Government Debt [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Corporate Obligations [Member] | Other Fixed Maturity Investments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Residential Mortgage Backed Agency [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Other Asset Backed [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Loan Repurchase Commitments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis		604
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Corporate Obligations [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Other Asset Backed [Member] | Asset-backed [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Loans Receivable and Other Instruments At Fair Value [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Residential Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	124	120
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Currency Derivatives [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	9	6
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Cash and Cash Equivalents [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Assets Of Consolidated V I Es [Member] | Other [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	14	14
Fair Value Inputs Level 3 [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	0	0
Fair Value Inputs Level 3 [Member] | Derivative Liabilities [Member] | Other Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis		49
Fair Value Inputs Level 3 [Member] | Liabilities Of Consolidated Vies [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	$ 280	$ 303

Fair Value Of Financial Instr_6

Fair Value Of Financial Instruments (Fair Value Hierarchy Table Presents The Company's Assets And Liabilities At Fair Value Not Recorded On The Company's Consolidated Balance Sheet) (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Variable Interest Entity Primary Beneficiary [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Variable interest entity notes	$ 451	$ 623
Carrying Reported Amount Fair Value Disclosure [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Measurements Nonrecurring [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Long-term debt	2,258	2,229
Medium-term notes	590	598
Investment agreements	268	269
Total liabilities	3,242	3,369
Gross	(246)	(282)
Ceded recoverable (liability)	(19)	(17)
Carrying Reported Amount Fair Value Disclosure [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Variable Interest Entity Primary Beneficiary [Member] | Fair Value Measurements Nonrecurring [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Variable interest entity notes	126	273
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Measurements Nonrecurring [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Long-term debt	736	631
Medium-term notes	395	396
Investment agreements	353	376
Total liabilities	1,613	1,679
Gross	874	811
Ceded recoverable (liability)	45	45
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Variable Interest Entity Primary Beneficiary [Member] | Fair Value Measurements Nonrecurring [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Variable interest entity notes	129	276
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 1 [Member] | Fair Value Measurements Nonrecurring [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Long-term debt	0	0
Medium-term notes	0	0
Investment agreements	0	0
Total liabilities	0	0
Gross	0	0
Ceded recoverable (liability)	0	0
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 1 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Fair Value Measurements Nonrecurring [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Variable interest entity notes	0	0
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 2 [Member] | Fair Value Measurements Nonrecurring [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Long-term debt	736	631
Medium-term notes	0	0
Investment agreements	0	0
Total liabilities	865	907
Gross	0	0
Ceded recoverable (liability)	0	0
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 2 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Fair Value Measurements Nonrecurring [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Variable interest entity notes	129	276
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 3 [Member] | Fair Value Measurements Nonrecurring [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Long-term debt	0	0
Medium-term notes	395	396
Investment agreements	353	376
Total liabilities	748	772
Gross	874	811
Ceded recoverable (liability)	45	45
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 3 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Fair Value Measurements Nonrecurring [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Variable interest entity notes	$ 0	$ 0

Fair Value Of Financial Instr_7

Fair Value Of Financial Instruments (Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Detail) - Fair Value Inputs Level 3 [Member] - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Accounts Notes And Loans Receivable [Line Items]
Beginning balance, fair value assets		$ 744	$ 649
Total gains/(losses) included in earnings, assets		8	(8)
Unrealized gains/(losses) included in OCI, assets	[1]	0	0
Purchases, assets		0	0
Issuances, assets		0	0
Settlements, assets		(605)	(3)
Sales, assets		0	0
Transfers into level 3, assets		0	0
Transfers out of level 3, assets		0	0
Ending balance, fair value assets		147	638
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets		11	(8)
Change in unrealized gains/(losses) for the period included in OCI for Assets still held	[1]	0	0
Beginning balance, fair value liabilities		462	500
Total (gains)/losses included in earnings, liabilities		15	(19)
Unrealized (gains)/losses included in OCI, liabilities	[2]	(14)	(48)
Purchases, liabilities		0	0
Issuances, liabilities		0	0
Settlements, liabilities		(78)	(9)
Sales, liabilities		0	0
Transfers into Level 3, liabilities		0	0
Transfers out of Level 3, liabilities		0	0
Ending balance, fair value liabilities		385	424
Change in unrealized (gains)/losses for the period included in earnings for liabilities still held, liabilities		(3)	(22)
Change in Unrealized (Gains)/ Losses for the Period Included in OCI for Liabilities still held	[2]	5	(46)
Residential Prime Financing Receivable [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance, fair value assets		120	136
Total gains/(losses) included in earnings, assets		9	(35)
Unrealized gains/(losses) included in OCI, assets	[1]	0	0
Purchases, assets		0	0
Issuances, assets		0	0
Settlements, assets		(5)	(3)
Sales, assets		0	0
Transfers into level 3, assets		0	0
Transfers out of level 3, assets		0	0
Ending balance, fair value assets		124	98
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets		8	(35)
Change in unrealized gains/(losses) for the period included in OCI for Assets still held	[1]	0	0
Loan Repurchase Commitments [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance, fair value assets		604	486
Total gains/(losses) included in earnings, assets		(4)	20
Unrealized gains/(losses) included in OCI, assets	[1]	0	0
Purchases, assets		0	0
Issuances, assets		0	0
Settlements, assets		(600)	0
Sales, assets		0	0
Transfers into level 3, assets		0	0
Transfers out of level 3, assets		0	0
Ending balance, fair value assets		0	506
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets		0	20
Change in unrealized gains/(losses) for the period included in OCI for Assets still held	[1]	0	0
Other Asset Backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance, fair value assets			1
Total gains/(losses) included in earnings, assets			0
Unrealized gains/(losses) included in OCI, assets	[1]		0
Purchases, assets			0
Issuances, assets			0
Settlements, assets			0
Sales, assets			0
Transfers into level 3, assets			0
Transfers out of level 3, assets			0
Ending balance, fair value assets			1
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets			0
Change in unrealized gains/(losses) for the period included in OCI for Assets still held	[1]		0
Medium Term Notes [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance, fair value liabilities		110	108
Total (gains)/losses included in earnings, liabilities		(7)	2
Unrealized (gains)/losses included in OCI, liabilities	[2]	2	(12)
Purchases, liabilities		0	0
Issuances, liabilities		0	0
Settlements, liabilities		0	0
Sales, liabilities		0	0
Transfers into Level 3, liabilities		0	0
Transfers out of Level 3, liabilities		0	0
Ending balance, fair value liabilities		105	98
Change in unrealized (gains)/losses for the period included in earnings for liabilities still held, liabilities		(7)	2
Change in Unrealized (Gains)/ Losses for the Period Included in OCI for Liabilities still held	[2]	2	(12)
Credit Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance, fair value liabilities			7
Total (gains)/losses included in earnings, liabilities			1
Unrealized (gains)/losses included in OCI, liabilities	[2]		0
Purchases, liabilities			0
Issuances, liabilities			0
Settlements, liabilities			0
Sales, liabilities			0
Transfers into Level 3, liabilities			0
Transfers out of Level 3, liabilities			0
Ending balance, fair value liabilities			8
Change in unrealized (gains)/losses for the period included in earnings for liabilities still held, liabilities			1
Change in Unrealized (Gains)/ Losses for the Period Included in OCI for Liabilities still held	[2]		0
Other Derivatives Liabilities [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance, fair value liabilities		49	34
Total (gains)/losses included in earnings, liabilities		0	3
Unrealized (gains)/losses included in OCI, liabilities	[2]	0	0
Purchases, liabilities		0	0
Issuances, liabilities		0	0
Settlements, liabilities		(49)	0
Sales, liabilities		0	0
Transfers into Level 3, liabilities		0	0
Transfers out of Level 3, liabilities		0	0
Ending balance, fair value liabilities		0	37
Change in unrealized (gains)/losses for the period included in earnings for liabilities still held, liabilities		0	3
Change in Unrealized (Gains)/ Losses for the Period Included in OCI for Liabilities still held	[2]	0	0
Variable Interest Entity Notes [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance, fair value liabilities		303	347
Total (gains)/losses included in earnings, liabilities		22	(25)
Unrealized (gains)/losses included in OCI, liabilities	[2]	(16)	(36)
Purchases, liabilities		0	0
Issuances, liabilities		0	0
Settlements, liabilities		(29)	(5)
Sales, liabilities		0	0
Transfers into Level 3, liabilities		0	0
Transfers out of Level 3, liabilities		0	0
Ending balance, fair value liabilities		280	281
Change in unrealized (gains)/losses for the period included in earnings for liabilities still held, liabilities		4	(28)
Change in Unrealized (Gains)/ Losses for the Period Included in OCI for Liabilities still held	[2]	3	(34)
Currency Derivatives [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance, fair value assets		6	8
Total gains/(losses) included in earnings, assets		3	10
Unrealized gains/(losses) included in OCI, assets	[1]	0	0
Purchases, assets		0	0
Issuances, assets		0	0
Settlements, assets		0	0
Sales, assets		0	0
Transfers into level 3, assets		0	0
Transfers out of level 3, assets		0	0
Ending balance, fair value assets		9	18
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets		3	10
Change in unrealized gains/(losses) for the period included in OCI for Assets still held	[1]	0	0
Other Assets [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance, fair value assets		14	18
Total gains/(losses) included in earnings, assets		0	(3)
Unrealized gains/(losses) included in OCI, assets	[1]	0	0
Purchases, assets		0	0
Issuances, assets		0	0
Settlements, assets		0	0
Sales, assets		0	0
Transfers into level 3, assets		0	0
Transfers out of level 3, assets		0	0
Ending balance, fair value assets		14	15
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets		0	(3)
Change in unrealized gains/(losses) for the period included in OCI for Assets still held	[1]	$ 0	0
Other Payable [Member]
Accounts Notes And Loans Receivable [Line Items]
Beginning balance, fair value liabilities			4
Total (gains)/losses included in earnings, liabilities			0
Unrealized (gains)/losses included in OCI, liabilities	[2]		0
Purchases, liabilities			0
Issuances, liabilities			0
Settlements, liabilities			(4)
Sales, liabilities			0
Transfers into Level 3, liabilities			0
Transfers out of Level 3, liabilities			0
Ending balance, fair value liabilities			0
Change in unrealized (gains)/losses for the period included in earnings for liabilities still held, liabilities			0
Change in Unrealized (Gains)/ Losses for the Period Included in OCI for Liabilities still held	[2]		$ 0
[1]	Reported within the “Unrealized gains (losses) on available-for-sale securities” on MBIA’s Consolidated Statement of Comprehensive Income/Loss.
[2]	Reported within the “Instrument-specific credit risk of liabilities measured at fair value” on MBIA’s Consolidated Statement of Comprehensive Income/Loss.

Fair Value Of Financial Instr_8

Fair Value Of Financial Instruments (Realized And Unrealized Gains And Losses Included In Earnings Pertaining To Level 3 Assets And Liabilities) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	$ 51	$ (63)
Variable Interest Entity Primary Beneficiary [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	(14)	15
Fair Value Inputs Level 3 [Member] | Total Gains (Losses) Included in Earnings [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gains (losses) on insured derivatives	0	(1)
Net gains (losses) on financial instruments at fair value and foreign exchange	7	(5)
Total revenues	(7)	11
Fair Value Inputs Level 3 [Member] | Change in Unrealized Gains (Losses) for the Period Included in Earnings for Assets and Liabilities still held [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gains (losses) on insured derivatives	0	(1)
Net gains (losses) on financial instruments at fair value and foreign exchange	7	(5)
Total revenues	14	14
Fair Value Inputs Level 3 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Total Gains (Losses) Included in Earnings [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	(14)	17
Fair Value Inputs Level 3 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Change in Unrealized Gains (Losses) for the Period Included in Earnings for Assets and Liabilities still held [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	$ 7	$ 20

Fair Value Of Financial Instr_9

Fair Value Of Financial Instruments (Gains And Losses On Fair Value Option Included In The Company's Consolidated Statements Of Operations) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange		$ 51	$ (63)
Non Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange		51	(63)
Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange		(14)	15
Investments Carried At Fair Value [Member] | Non Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	[1]	3	(20)
Fixed Maturity Securities Held At Fair Value - VIE [Member] | Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	[2]	1	(6)
Loans Receivable and Other Instruments at Fair Value [Member] | Variable Interest Entity [Member] | Residential Mortgage Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	[2]	9	(35)
Loan Repurchase Commitments [Member] | Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	[2]	(4)	20
Other Assets [Member] | Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	[2]	0	(3)
Medium Term Notes [Member] | Non Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	[1]	7	(2)
Variable Interest Entity Notes [Member] | Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	[2]	$ (23)	$ 27
[1]	Reported within “Net gains (losses) of financial instruments at fair value and foreign exchange” on MBIA’s consolidated statements of operations.
[2]	Reported within “Net gains (losses) of financial instruments at fair value and foreign exchange-VIE” on MBIA’s consolidated statements of operations.

Fair Value Of Financial Inst_10

Fair Value Of Financial Instruments (Aggregate Fair Value And Remaining Contractual Principal Balance Outstanding On Fair Value Option) (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Residential Mortgage Loans [Member] | Loans Receivable [Member]
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items]
Loans receivable and other instruments, contractual outstanding principal	$ 85	$ 89
Loans receivable and other instruments, 90 days or more past due, contractual outstanding principal	144	147
Loans receivable and other instruments, fair value	85	89
Loans receivable and other instruments, 90 days or more past due, fair value	39	31
Loans receivable and other instruments, difference	0	0
Loans receivable and other instruments, 90 days or more past due, difference	105	116
Total Loans Receivable and Other Instruments [Member] | Loans Receivable [Member]
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items]
Loans receivable and other instruments, contractual outstanding principal	229	236
Loans receivable and other instruments, fair value	124	120
Loans receivable and other instruments, difference	105	116
Variable Interest Entity Notes [Member]
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items]
Long-term debt instruments, contractual outstanding principal	1,080	1,117
Long-term debt instruments, fair value	325	350
Long-term debt instruments, difference	755	767
Medium Term Notes [Member]
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items]
Long-term debt instruments, contractual outstanding principal	118	122
Long-term debt instruments, fair value	105	110
Long-term debt instruments, difference	$ 13	$ 12

Investments (Narrative) (Detail

Investments (Narrative) (Detail) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021USD ($)security	Dec. 31, 2020USD ($)security
Schedule Of Investments [Line Items]
Fair value of securities on deposit with various regulatory authorities | $	$ 11	$ 11
Fair value of securities pledged as collateral | $	$ 278	$ 282
Number of securities in unrealized loss position for a continuous 12 month period | security	45	42
Rate that a security's fair value is below book value	5.00%	5.00%
Securities In Unrealized Loss Position [Member]
Schedule Of Investments [Line Items]
Weighted average contractual maturity period in years for securities in an unrealized loss position	14 years	9 years
Fair Value Below Book Value Greater Than Five Percent [Member]
Schedule Of Investments [Line Items]
Number of securities in unrealized loss position for a continuous 12 month period | security	7	9

Investments (Amortized Cost And

Investments (Amortized Cost And Fair Value Of Available-For-Sale and Held-To-Maturity Investment Portfolios) (Detail) - Fixed Maturities [Member] - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	$ 2,728	$ 2,360
Allowance for Credit Losess	0	0
Gross unrealized gains	115	184
Gross unrealized losses	(28)	(5)
Total available-for-sale, fair value	2,815	2,539
U S Treasury And Government [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	1,006	775
Allowance for Credit Losess	0	0
Gross unrealized gains	47	75
Gross unrealized losses	(5)	(1)
Total available-for-sale, fair value	1,048	849
US States And Political Subdivisions [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	160	162
Allowance for Credit Losess	0	0
Gross unrealized gains	25	32
Gross unrealized losses	0	0
Total available-for-sale, fair value	185	194
Foreign Governments [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	13	11
Allowance for Credit Losess	0	0
Gross unrealized gains	0	1
Gross unrealized losses	0	0
Total available-for-sale, fair value	13	12
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	883	827
Allowance for Credit Losess	0	0
Gross unrealized gains	31	64
Gross unrealized losses	(16)	(1)
Total available-for-sale, fair value	898	890
Residential Mortgage-Backed Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	285	305
Allowance for Credit Losess	0	0
Gross unrealized gains	7	8
Gross unrealized losses	(3)	(1)
Total available-for-sale, fair value	289	312
Residential Mortgage-Backed Non-Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	83	22
Allowance for Credit Losess	0	0
Gross unrealized gains	4	3
Gross unrealized losses	(3)	0
Total available-for-sale, fair value	84	25
Commercial Mortgage-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	11	17
Allowance for Credit Losess	0	0
Gross unrealized gains	1	1
Gross unrealized losses	0	0
Total available-for-sale, fair value	12	18
Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	114	120
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(1)	(2)
Total available-for-sale, fair value	113	118
Other Asset-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	173	121
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Total available-for-sale, fair value	$ 173	$ 121

Investments (Distribution By Co

Investments (Distribution By Contractual Maturity Of Available-For-Sale and Held-To-Maturity Investments) (Detail) - Fixed Maturities [Member] $ in Millions	Mar. 31, 2021USD ($)
Available For Sale Securities [Abstract]
Due in one year or less	$ 827
Due after one year through five years	374
Due after five years through ten years	231
Due after ten years	630
Mortgage-Backed and Asset-Backed	666
Total Available-For-Sale, amortized cost	2,728
Due in one year or less	829
Due after one year through five years	387
Due after five years through ten years	248
Due after ten years	680
Mortgage-Backed and Asset-Backed	671
Total Available-For-Sale, fair value	$ 2,815

Investments (Gross Unrealized L

Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) - Fixed Maturities [Member] - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Available For Sale Securities [Abstract]
Less than 12 months, fair value	$ 646	$ 325
Less than 12 months, unrealized losses	(26)	(3)
12 months or longer, fair value	88	91
12 months or longer, unrealized losses	(2)	(2)
Total available-for-sale, fair value	734	416
Total available-for-sale, unrealized losses	(28)	(5)
U S Treasury And Government [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	125	99
Less than 12 months, unrealized losses	(5)	(1)
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	125	99
Total available-for-sale, unrealized losses	(5)	(1)
US States And Political Subdivisions [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	4
Less than 12 months, unrealized losses	0
12 months or longer, fair value	0
12 months or longer, unrealized losses	0
Total available-for-sale, fair value	4
Total available-for-sale, unrealized losses	0
Foreign Government Debt [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	6	2
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	6	2
Total available-for-sale, unrealized losses	0	0
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	278	103
Less than 12 months, unrealized losses	(15)	(1)
12 months or longer, fair value	15	7
12 months or longer, unrealized losses	(1)	0
Total available-for-sale, fair value	293	110
Total available-for-sale, unrealized losses	(16)	(1)
Residential Mortgage Backed Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	100	53
Less than 12 months, unrealized losses	(3)	(1)
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	100	53
Total available-for-sale, unrealized losses	(3)	(1)
Residential Mortgage Backed Non Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	35	2
Less than 12 months, unrealized losses	(3)	0
12 months or longer, fair value	1	1
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	36	3
Total available-for-sale, unrealized losses	(3)	0
Commercial Mortgage Backed Securities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	2	0
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	0	5
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	2	5
Total available-for-sale, unrealized losses	0	0
Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	19	37
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	71	78
12 months or longer, unrealized losses	(1)	(2)
Total available-for-sale, fair value	90	115
Total available-for-sale, unrealized losses	(1)	(2)
Other Asset Backed [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	77	29
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	1	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	78	29
Total available-for-sale, unrealized losses	$ 0	$ 0

Investments (Distribution Of Se

Investments (Distribution Of Securities By Percentage Of Fair Value Below Book Value By More Than 5% For A Continuous Twelve Month Period Or Longer) (Detail) - Unrealized loss position > 12 months $ in Millions	Mar. 31, 2021USD ($)security
> 5% To 15% [Member]
Available For Sale Securities [Abstract]
Number of available-for-sale securities in unrealized loss position | security	2
Fixed-maturity securities held as available-for-sale, amortized cost	$ 1
Available For Sale Securities	$ 1
Held To Maturity Securities [Abstract]
Percentage Of Fair Value Below Book Value Minimum	5.00%
Percentage Of Fair Value Below Book Value Maximum	15.00%
> 15% To 25% [Member]
Available For Sale Securities [Abstract]
Number of available-for-sale securities in unrealized loss position | security	3
Fixed-maturity securities held as available-for-sale, amortized cost	$ 1
Available For Sale Securities	$ 1
Held To Maturity Securities [Abstract]
Percentage Of Fair Value Below Book Value Minimum	15.00%
Percentage Of Fair Value Below Book Value Maximum	25.00%
> 50% [Member]
Available For Sale Securities [Abstract]
Number of available-for-sale securities in unrealized loss position | security	2
Fixed-maturity securities held as available-for-sale, amortized cost	$ 0
Available For Sale Securities	$ 0
Held To Maturity Securities [Abstract]
Percentage Of Fair Value Below Book Value Minimum	50.00%
Greater Than 5% [Member]
Available For Sale Securities [Abstract]
Number of available-for-sale securities in unrealized loss position | security	7
Fixed-maturity securities held as available-for-sale, amortized cost	$ 2
Available For Sale Securities	$ 2

Investments (Securities Held In

Investments (Securities Held In Unrealized Loss Position And Insured By Financial Guarantor) (Detail) - Financial Guarantee [Member] $ in Millions	Mar. 31, 2021USD ($)
Schedule Of Investments [Line Items]
Total Available-For-Sale, Fair Value	$ 121
Gross unrealized losses	(13)
Loss and loss adjustment expense reserves	44	[1]
Mortgage-backed [Member]
Schedule Of Investments [Line Items]
Total Available-For-Sale, Fair Value	36
Gross unrealized losses	(3)
Loss and loss adjustment expense reserves	44	[1]
Corporate Obligations [Member]
Schedule Of Investments [Line Items]
Total Available-For-Sale, Fair Value	85
Gross unrealized losses	(10)
Loss and loss adjustment expense reserves	$ 0	[1]
[1]	Insurance loss reserve estimates are based on the proportion of par value owned to the total amount of par value insured and are discounted using a discount rate equal to the risk-free rate applicable to the currency and weighted average remaining life of the insurance contract and may differ from the fair value.

Investments - (Summary of Allow

Investments - (Summary of Allowance for Credit Losses on HTM Investments) (Detail) - Variable Interest Entity Primary Beneficiary [Member] - Accounting Standards Update 2016-13 [Member] $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Beginning balance	$ 37	[1]
Current period provision for expected credit losses	9
Initial allowance recognized for PCD assets	0
Write- Offs	0
Recoveries	0
Ending balance	46
Corporate Obligations [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Beginning balance	37	[1]
Current period provision for expected credit losses	9
Initial allowance recognized for PCD assets	0
Write- Offs	0
Recoveries	0
Ending balance	$ 46
[1]	Represents transition adjustment upon adoption of ASU 2016-13.

Investments (Net Realized Gains

Investments (Net Realized Gains (Losses) From Sales Of Available-For-Sale Securities) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Investments [Abstract]
Proceeds from sales	$ 178	$ 279
Available For Sale Securities Realized Gain Loss [Abstract]
Gross realized gains	4	11
Gross realized losses	$ (5)	$ (8)

Investments (Portion Of Unreali

Investments (Portion Of Unrealized Gains And Losses On Equity Investments Held) (Detail) - Equity Securities [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Gains (losses) on equity investments [Member]
Gain (Loss) on Investments [Line Items]
Realized investment gains (losses)	$ 2	$ (13)
Gains (losses) on equity investments sold during the period [Member]
Gain (Loss) on Investments [Line Items]
Realized investment gains (losses)	0	0
Gains (losses) on equity investments still held at the end of the period [Member]
Gain (Loss) on Investments [Line Items]
Realized investment gains (losses)	$ 2	$ (13)

Derivative Instruments (Narrati

Derivative Instruments (Narrative) (Detail) $ in Millions	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)
Derivative [Line Items]
Cash collateral posted to derivative counterparties	$ 0	$ 0
Securities posted as collateral to derivative counterparties	$ 154	$ 214
Number of credit support annexes	1	1
Fair value of Credit Support Annex	$ 1	$ 1

Derivative Instruments (Credit

Derivative Instruments (Credit Derivatives Sold) (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Insured Swaps [Member]
Derivative [Line Items]
Weighted average remaining expected maturity	13 years 9 months 18 days	13 years 10 months 24 days
Insurance Operations [Member]
Derivative [Line Items]
Derivative notional amount	$ 1,725	$ 1,743
Total fair value of credit derivatives	(1)	(2)
Insurance Operations [Member] | Insured Swaps [Member]
Derivative [Line Items]
Derivative notional amount	1,725	1,743
Total fair value of credit derivatives	(1)	(2)
Credit Rating Aaa [Member] | Insurance Operations [Member]
Derivative [Line Items]
Derivative notional amount	0	0
Total fair value of credit derivatives	0	0
Credit Rating Aaa [Member] | Insurance Operations [Member] | Insured Swaps [Member]
Derivative [Line Items]
Derivative notional amount	0	0
Credit Rating Aa [Member] | Insurance Operations [Member]
Derivative [Line Items]
Derivative notional amount	56	58
Total fair value of credit derivatives	0	0
Credit Rating Aa [Member] | Insurance Operations [Member] | Insured Swaps [Member]
Derivative [Line Items]
Derivative notional amount	56	58
Credit Rating A [Member] | Insurance Operations [Member]
Derivative [Line Items]
Derivative notional amount	1,311	1,327
Total fair value of credit derivatives	0	(1)
Credit Rating A [Member] | Insurance Operations [Member] | Insured Swaps [Member]
Derivative [Line Items]
Derivative notional amount	1,311	1,327
Credit Rating Bbb [Member] | Insurance Operations [Member]
Derivative [Line Items]
Derivative notional amount	358	358
Total fair value of credit derivatives	(1)	(1)
Credit Rating Bbb [Member] | Insurance Operations [Member] | Insured Swaps [Member]
Derivative [Line Items]
Derivative notional amount	358	358
Credit Rating Below Investment Grade [Member] | Insurance Operations [Member]
Derivative [Line Items]
Derivative notional amount	0	0
Credit Rating Below Investment Grade [Member] | Insurance Operations [Member] | Insured Swaps [Member]
Derivative [Line Items]
Derivative notional amount	$ 0	$ 0

Derivative Instruments (Total F

Derivative Instruments (Total Fair Value Of Company's Derivative Assets And Liabilities By Instrument And Balance Sheet Location, Before Counterparty Netting) (Detail) - Not Designated as Hedging Instrument [Member] - Derivative Instrument [Member] - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative notional amount		$ 2,447	$ 2,534
Derivative Assets, Not designated, Fair Value	[1]	10	7
Derivative Liabilities, Not designated, Fair Value	[1]	(136)	(225)
Insured swaps [Member]
Derivative [Line Items]
Derivative notional amount		1,725	1,743
Insured swaps [Member] | Other assets [Member]
Derivative [Line Items]
Derivative Assets, Not designated, Fair Value	[1]	0	0
Insured swaps [Member] | Derivative liabilities [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	[1]	(1)	(2)
Interest rate swaps [Member]
Derivative [Line Items]
Derivative notional amount		429	437
Interest rate swaps [Member] | Other assets [Member]
Derivative [Line Items]
Derivative Assets, Not designated, Fair Value	[1]	1	1
Interest rate swaps [Member] | Derivative liabilities [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	[1]	(125)	(164)
Interest rate swaps-embedded [Member]
Derivative [Line Items]
Derivative notional amount		241	252
Interest rate swaps-embedded [Member] | Medium-term notes [Member]
Derivative [Line Items]
Derivative Assets, Not designated, Fair Value	[1]	0	0
Derivative Liabilities, Not designated, Fair Value	[1]	(10)	(10)
Currency swaps-VIE [Member]
Derivative [Line Items]
Derivative notional amount		52	53
Currency swaps-VIE [Member] | Other assets-VIE [Member]
Derivative [Line Items]
Derivative Assets, Not designated, Fair Value	[1]	9	6
Currency swaps-VIE [Member] | Derivative liabilities-VIE [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	[1]	$ 0	0
All other [Member]
Derivative [Line Items]
Derivative notional amount			49
All other [Member] | Other assets [Member]
Derivative [Line Items]
Derivative Assets, Not designated, Fair Value	[1]		0
All other [Member] | Derivative liabilities [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	[1]		$ (49)
[1]	In accordance with the accounting guidance for derivative instruments and hedging activities, the balance sheet location of the Company’s embedded derivative instruments is determined by the location of the related host contract.

Derivative Instruments (Effect

Derivative Instruments (Effect Of Derivative Instruments On Consolidated Statements Of Operations) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative [Line Items]
Net gain/(loss) recognized in income	$ 37	$ (50)
Unrealized Gains Losses On Insured Derivatives [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	0	(1)
Net gains (losses) on financial instruments at fair value and foreign exchange [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	35	(56)
Net gains (losses) on financial instruments at fair value and foreign exchange [Member] | Currency Swaps Vie [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	2	10
Net gains (losses) on financial instruments at fair value and foreign exchange [Member] | All Other [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	$ 0	$ (3)

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Non Variable Interest Entities [Line Items]
NOL carryforward	$ 3,200
Foreign tax credit	61
Unrecognized Tax Benefits	0	$ 0
Valuation allowance on net deferred tax asset	$ 1,000	$ 966

Income Taxes (Income Taxes And

Income Taxes (Income Taxes And Related Effective Tax Rates) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disclosure Income Taxes Income Taxes And Related Effective Tax Rates [Abstract]
Income (loss) before income taxes	$ (106)	$ (333)
Provision (benefit) for income taxes	$ 0	$ 0
Effective tax rate	0.00%	0.00%

Business Segments (Narrative) (

Business Segments (Narrative) (Detail)	3 Months Ended
	Mar. 31, 2021segments
Disclosure Business Segments Summary Of Companys Segment Results [Abstract]
Number of operating segments	3

Business Segments (Summary Of C

Business Segments (Summary Of Company's Segment Results) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues	[1]	$ 35	$ 43
Net gains (losses) on financial instruments at fair value and foreign exchange		51	(63)
Revenues of consolidated VIEs		(14)	14
Inter-segment revenues	[2]	0	0
Total revenues		72	(6)
Losses and loss adjustment		98	243
Operating		28	20
Interest		41	47
Expenses of consolidated VIEs		11	17
Inter-segment expenses	[2]	0	0
Total expenses		178	327
Income (loss) before income taxes		(106)	(333)
Identifiable assets		5,375		$ 5,751
Operating Segments [Member] | US Public Finance [Member]
Segment Reporting Information [Line Items]
Revenues	[1]	23	30
Net gains (losses) on financial instruments at fair value and foreign exchange		(3)	(18)
Revenues of consolidated VIEs		0	0
Inter-segment revenues	[2]	8	7
Total revenues		28	19
Losses and loss adjustment		109	48
Operating		4	2
Interest		0	0
Expenses of consolidated VIEs		0	0
Inter-segment expenses	[2]	14	14
Total expenses		127	64
Income (loss) before income taxes		(99)	(45)
Identifiable assets		3,562
Operating Segments [Member] | Corporate Operations [Member]
Segment Reporting Information [Line Items]
Revenues	[1]	5	6
Net gains (losses) on financial instruments at fair value and foreign exchange		55	(56)
Revenues of consolidated VIEs		0	0
Inter-segment revenues	[2]	18	18
Total revenues		78	(32)
Losses and loss adjustment		0	0
Operating		21	14
Interest		14	16
Expenses of consolidated VIEs		0	0
Inter-segment expenses	[2]	6	6
Total expenses		41	36
Income (loss) before income taxes		37	(68)
Identifiable assets		899
Operating Segments [Member] | International And Structured Finance Insurance [Member]
Segment Reporting Information [Line Items]
Revenues	[1]	7	7
Net gains (losses) on financial instruments at fair value and foreign exchange		(1)	11
Revenues of consolidated VIEs		(14)	14
Inter-segment revenues	[2]	4	4
Total revenues		(4)	36
Losses and loss adjustment		(11)	195
Operating		3	4
Interest		27	31
Expenses of consolidated VIEs		11	17
Inter-segment expenses	[2]	10	9
Total expenses		40	256
Income (loss) before income taxes		(44)	(220)
Identifiable assets		3,477
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Revenues	[1]	0	0
Net gains (losses) on financial instruments at fair value and foreign exchange		0	0
Revenues of consolidated VIEs		0	0
Inter-segment revenues	[2]	(30)	(29)
Total revenues		(30)	(29)
Losses and loss adjustment		0	0
Operating		0	0
Interest		0	0
Expenses of consolidated VIEs		0	0
Inter-segment expenses	[2]	(30)	(29)
Total expenses		(30)	(29)
Income (loss) before income taxes		0	$ 0
Identifiable assets	[3]	$ (2,563)
[1]	Represents the sum of third-party financial guarantee net premiums earned, net investment income, insurance-related fees and reimbursements and other fees.
[2]	Represents intercompany premium income and expense and intercompany interest income and expense pertaining to intercompany receivables and payables.
[3]	Consists principally of intercompany reinsurance balances.

Earnings Per Share (Narrative)

Earnings Per Share (Narrative) (Detail) - shares shares in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Shares [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.9	0.9

Earnings Per Share (Computation

Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Basic earnings per share:
Net income (loss) available to common shareholders		$ (106)	$ (333)
Basic weighted average shares	[1]	49,258,110	72,089,016
Net income (loss) per basic common share		$ (2.16)	$ (4.62)
Diluted earnings per share:
Net income (loss) available to common shareholders		$ (106)	$ (333)
Diluted weighted average shares	[1]	49,258,110	72,089,016
Net income (loss) per diluted common share		$ (2.16)	$ (4.62)
Potentially dilutive securities excluded from the calculation of diluted EPS because of antidilutive affect		5,000,000	4,900,000
[1]	Includes 0.9 million of participating securities that met the service condition and were eligible to receive nonforfeitable dividends or dividend equivalents for each of the three months ended March 31, 2021 and 2020, respectively.

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Changes In The Components Of AOCI) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Beginning balance	$ 115
Other comprehensive income (loss) before reclassifications	(91)
Amounts reclassified from AOCI	15
Total other comprehensive income (loss)	(76)	$ 93
Ending balance	39
Unrealized gains (losses) on AFS, net [Member]
Beginning balance	176
Other comprehensive income (loss) before reclassifications	(87)
Amounts reclassified from AOCI	(5)
Total other comprehensive income (loss)	(92)
Ending balance	84
Foreign currency translation, net [Member]
Beginning balance	(10)
Other comprehensive income (loss) before reclassifications	1
Amounts reclassified from AOCI	0
Total other comprehensive income (loss)	1
Ending balance	(9)
Instrument-specific credit risk of liabilities measured at fair value, net [Member]
Beginning balance	(51)
Other comprehensive income (loss) before reclassifications	(5)
Amounts reclassified from AOCI	20
Total other comprehensive income (loss)	15
Ending balance	$ (36)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Details Of The Reclassification From AOCI) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net gains (losses) on financial instruments at fair value and foreign exchange	$ 51	$ (63)
Income (loss) before income taxes	(106)	(333)
Net income (loss)	(106)	(333)
Amounts reclassified from AOCI [Member]
Net income (loss)	(15)	1
Unrealized gains (losses) on AFS, net [Member] | Amounts reclassified from AOCI [Member]
Net gains (losses) on financial instruments at fair value and foreign exchange	5	3
Income (loss) before income taxes	5	3
Instrument-specific credit risk of liabilities measured at fair value, net [Member] | Amounts reclassified from AOCI [Member]
Net gains (losses) on financial instruments at fair value and foreign exchange	$ (20)	$ (2)

Commitments and Contingencies_2

Commitments and Contingencies (Narrative) (Detail) $ in Millions	Feb. 10, 2021USD ($)	Mar. 31, 2021USD ($)Lawsuits
Commitments And Contingencies [Line Items]
Other material lawsuits pending | Lawsuits		0
Credit Suisse [Member]
Commitments And Contingencies [Line Items]
Damages Sought Value		$ 604
Damages Paid Value	$ 600
Fuel Line Lenders [Member]
Commitments And Contingencies [Line Items]
PREPA working capital		$ 700

Commitments and Contingencies_3

Commitments and Contingencies (Lease Disclosures) (Detail) $ in Millions	Mar. 31, 2021USD ($)
Operating lease liability	us-gaap:OperatingLeaseLiability
Operating lease weighted average remaining lease term	8 years 4 months 24 days
Operating lease weighted average discount rate percent	7.50%
Operating leases future minimum payments due	$ 28
Other Assets [Member]
Operating lease right of use asset	19
Other Liabilities [Member]
Operating lease liability	$ 19