Ally Financial (ALLY) 10-Q 4 May 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	3 Months Ended
	Mar. 31, 2017	May 02, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Entity Registrant Name	Ally Financial Inc.
Entity Central Index Key	40,729
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		459,193,676
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 8,257,669,855

Consolidated Statement of Incom

Consolidated Statement of Income Consolidated Statement of Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Financing Revenue and Other Income [Line Items]
Interest and Fee Income, Loans and Leases	$ 1,368	$ 1,235
Interest and Dividend Income, Securities, Operating, Available-for-sale	134	102
Interest Income, Deposits with Financial Institutions	5	3
Operating Leases, Income Statement, Lease Revenue	543	769
Total financing revenue and other interest income	2,050	2,109
Interest Expense [Abstract]
Interest Expense, Deposits	231	193
Interest Expense, Short-term Borrowings	27	13
Interest Expense, Long-term Debt	424	442
Interest Expense	682	648
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	389	510
Net Financing Revenue	979	951
Other revenue [Abstract]
Insurance Services Revenue	241	230
Gain (Loss) on Sales of Loans, Net	14	1
Gain (Loss) on Extinguishment of Debt	(1)	(4)
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	27	54
Noninterest Income, Other Operating Income	115	95
Nonoperating Income (Expense)	396	376
Revenues	1,375	1,327
Provision for Loan Losses Expensed	271	220
Noninterest Expense [Abstract]
Labor and Related Expense	285	252
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	88	73
Other Noninterest Expense	405	385
Noninterest Expense	778	710
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	326	397
Income Tax Expense (Benefit)	113	150
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	213	247
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	1	3
Net Income (Loss) Attributable to Parent	214	250
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	20	146
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 234	$ 396
Earnings Per Share, Basic [Abstract]
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.46	$ 0.48
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0	0.01
Earnings Per Share, Basic	0.46	0.49
Earnings Per Share, Diluted [Abstract]
Income (Loss) from Continuing Operations, Per Diluted Share	0.46	0.48
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0	0.01
Earnings Per Share, Diluted	0.46	0.49
Common Stock, Dividends, Per Share, Declared	$ 0.08	$ 0
Retained Earnings [Member]
Net Income (Loss) Attributable to Parent	$ 214	$ 250

Consolidated Balance Sheet & Mi

Consolidated Balance Sheet & Mini Balance Sheet - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Held-to-maturity Securities, Fair Value	$ 1,063	$ 789
Assets [Abstract]
Cash and Due from Banks	1,513	1,547
Interest-bearing Deposits in Banks and Other Financial Institutions	2,789	4,387
Cash and Cash Equivalents, at Carrying Value	4,302	5,934
Available-for-sale securities	20,308	18,926
Held-to-maturity securities	1,104	839
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	1	0
Finance receivables and loans, net [Abstract]
Loans and Leases Receivable, Gross	119,002	118,944
Loans and Leases Receivable, Allowance	(1,155)	(1,144)
Loans and Leases Receivable, Net Amount	117,847	117,800
Property Subject to or Available for Operating Lease, Net	10,461	11,470
Premiums receivable and other insurance assets	1,944	1,905
Other Assets	6,134	6,854
Assets	162,101	163,728
Liabilities and Equity [Abstract]
Noninterest-bearing deposit liabilities	102	84
Interest-bearing Deposit Liabilities	84,384	78,938
Deposits	84,486	79,022
Short-term Debt	8,371	12,673
Long-term Debt	51,061	54,128
Interest payable	382	351
Unearned Premiums	2,514	2,500
Accounts Payable and Accrued Liabilities	1,922	1,737
Liabilities	148,736	150,411
Equity [Abstract]
Common Stocks, Including Additional Paid in Capital, Net of Discount	21,187	21,166
Retained Earnings (Accumulated Deficit)	(6,975)	(7,151)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(321)	(341)
Treasury stock, Value	(526)	(357)
Stockholders' Equity Attributable to Parent, Total	13,365	13,317
Liabilities and Equity	162,101	163,728
Variable Interest Entity, Primary Beneficiary [Member]
Finance receivables and loans, net [Abstract]
Loans and Leases Receivable, Gross	22,550	24,630
Loans and Leases Receivable, Allowance	(154)	(173)
Loans and Leases Receivable, Net Amount	22,396	24,457
Property Subject to or Available for Operating Lease, Net	1,273	1,745
Other Assets	914	1,390
Assets	24,583	27,592
Liabilities and Equity [Abstract]
Long-term Debt	13,331	13,259
Accounts Payable and Accrued Liabilities	12	12
Liabilities	$ 13,343	$ 13,271

Consolidated Balance Sheet and

Consolidated Balance Sheet and Mini Balance Sheet (Paranthetical) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	1,100,000,000	1,100,000,000
Common Stock, Shares, Issued	488,997,931	485,707,644
Common Stock, Shares, Outstanding	462,193,424	467,000,306
Treasury Stock, Shares	26,804,507	18,707,338
Held-to-maturity Securities, Fair Value	$ 1,063	$ 789

Consolidated Statement of Chang

Consolidated Statement of Changes in Equity - USD ($) $ in Millions	Total	Common stock and paid-in capital [Member]	Preferred stock [Member]	Retained Earnings [Member]	Accumulated other comprehensive (loss) income [Member]	Treasury stock [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (231)				$ (231)
Stockholders' Equity Attributable to Parent at Dec. 31, 2015	13,439	$ 21,100	$ 696	$ (8,110)		$ (16)
Net Income (Loss) Attributable to Parent	250			250
Dividends, Preferred Stock, Cash	(15)			(15)
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	17	17
Other Comprehensive Income (Loss), Net of Tax					146
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	146
Treasury Stock, Value, Acquired, Cost Method	(14)					(14)
Stockholders' Equity Attributable to Parent at Mar. 31, 2016	$ 13,823	21,117	696	(7,875)		(30)
Common Stock, Dividends, Per Share, Declared	$ 0
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (85)				(85)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(341)				(341)
Stockholders' Equity Attributable to Parent at Dec. 31, 2016	13,317	21,166	0	(7,151)		(357)
Net Income (Loss) Attributable to Parent	214			214
Dividends, Preferred Stock, Cash	0
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	21	21
Other Comprehensive Income (Loss), Net of Tax					20
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	20
Treasury Stock, Value, Acquired, Cost Method	(169)					(169)
Dividends, Common Stock, Cash	(38)			(38)
Stockholders' Equity Attributable to Parent at Mar. 31, 2017	$ 13,365	$ 21,187	$ 0	$ (6,975)		$ (526)
Common Stock, Dividends, Per Share, Declared	$ 0.08
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (321)				$ (321)

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net Cash Provided by Operating Activities [Abstract]
Net Income (Loss) Attributable to Parent	$ 214	$ 250
Depreciation, Amortization and Accretion, Net	534	653
Provision for Loan Losses Expensed Including Discontinued Operations	271	220
Gain Loss on Sales of Loans Net Including Discontinued Operations	(14)	(1)
Availableforsale Securities Gross Realized Gain Loss Excluding Otti Including Disc Ops	(27)	(54)
Gain (Loss) on Extinguishment of Debt	1	4
Payments for Origination and Purchases of Loans Held-for-sale	(21)	(44)
Proceeds from Sale of Loans Held-for-sale	20	104
Increase (Decrease) in Deferred Income Taxes	91	147
Increase (Decrease) in Interest Payable, Net	31	24
Increase (Decrease) in Other Operating Assets	60	46
Increase (Decrease) in Other Operating Liabilities	(20)	(122)
Increase (Decrease) in Other Operating Assets and Liabilities, Net	35	(25)
Net cash provided by (used in) operating activities	1,175	1,202
Payments to Acquire Available-for-sale Securities	(2,833)	(4,870)
Proceeds from sales of available-for-sale securities	1,045	4,175
Proceeds from maturities and repayment of available-for-sale securities	589	409
Payments to Acquire Held-to-maturity Securities	(215)	(118)
Proceeds from Sale and Maturity of Held-to-maturity Securities	5	0
Payments for (Proceeds from) Loans and Leases	(405)	(1,402)
Proceeds from Sale of Loans Held-for-investment	1,164	2,594
Originations and repayments of loans held-for-investment and other	1,174	684
Purchases of operating lease assets	(893)	(701)
Disposals of operating lease assets	1,545	1,535
Increase (Decrease) in Restricted Cash	355	48
Increase (Decrease) in Non marketable equity securities	213	(315)
Payments for (Proceeds from) Other Investing Activities	(59)	(20)
Net cash provided by investing activities	(663)	651
Net Cash Used in Financing Activities [Abstract]
Proceeds from (Repayments of) Short-term Debt	(4,303)	(2,739)
Increase (Decrease) in Deposits	5,451	3,780
Proceeds from issuance of long-term debt	4,488	4,244
Repayments of long-term debt	(7,573)	(8,490)
Payments for Repurchase of Common Stock	(169)	(14)
Payments of Dividends	(38)	(15)
Net cash (used in) provided by financing activities	(2,144)	(3,234)
Effect of exchange-rate changes on cash and cash equivalents	0	2
Cash and Cash Equivalents, Period Increase (Decrease)	(1,632)	(1,379)
Cash and Cash Equivalents, at Carrying Value	5,934	6,380
Cash and Cash Equivalents, at Carrying Value	4,302	5,001
Supplemental Cash Flow Information [Abstract]
Interest Paid	648	626
Income Taxes Paid	2	0
Held-to-maturity securities received in consideration for loans sold	56	0
Transfer of Portfolio Loans and Leases to Held-for-sale	1,213	2,599
Proceeds from sales and repayments of mortgage loans held-for-investment originally designated as held-for-sale	$ 8	$ 9

Description of Business, Basis

Description of Business, Basis of Presentation, and Changes in Significant Accounting Policies	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block]	Description of Business, Basis of Presentation, and Changes in Significant Accounting Policies Ally Financial Inc. (together with its consolidated subsidiaries unless the context requires otherwise, Ally, the Company, or we, us, or our) is a leading digital financial services company offering diversified financial products for consumers, businesses, automotive dealers and corporate clients . Our legacy dates back to 1919, and Ally was redesigned in 2009 with a distinctive brand and relentless focus on our customers. We reconverted to a Delaware corporation in 2009 and are registered as a bank holding company (BHC) under the Bank Holding Company Act of 1956 as amended and a financial holding company (FHC) under the Gramm-Leach-Bliley Act of 1999 as amended . Our banking subsidiary, Ally Bank, is an award-winning online bank, and an indirect, wholly-owned subsidiary of Ally Financial Inc. Collectively, Ally Financial Inc. and its subsidiaries offer a variety of deposit and banking products including CDs, online savings, money market and checking accounts, IRA products, automotive lending products to customers and dealers, corporate finance lending, insurance products and services, a cash back credit card, mortgage lending offerings, and wealth management solutions. Our accounting and reporting policies conform to accounting principles generally accepted in the United States of America (GAAP). Additionally, where applicable, the policies conform to the accounting and reporting guidelines prescribed by bank regulatory authorities. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and that affect income and expenses during the reporting period and related disclosures. In developing the estimates and assumptions, management uses all available evidence; however, actual results could differ because of uncertainties associated with estimating the amounts, timing, and likelihood of possible outcomes. Our most significant estimates pertain to the allowance for loan losses, valuations of automotive lease assets and residuals, fair value of financial instruments, legal and regulatory reserves, and the determination of the provision for income taxes. The Condensed Consolidated Financial Statements at March 31, 2017 , and for the three months ended March 31, 2017 , and 2016 , are unaudited but reflect all adjustments that are, in management’s opinion, necessary for the fair presentation of the results for the interim periods presented. All such adjustments are of a normal recurring nature. These unaudited Condensed Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements (and the related Notes) included in our Annual Report on Form 10-K for the year ended December 31, 2016 , as filed on February 27, 2017, with the U.S. Securities and Exchange Commission (SEC). Significant Accounting Policies Income Taxes In calculating the provision for interim income taxes, in accordance with Accounting Standards Codification (ASC) 740, Income Taxes , we apply an estimated annual effective tax rate to year-to-date ordinary income. At the end of each interim period, we estimate the effective tax rate expected to be applicable for the full fiscal year. This method differs from that described in Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K, which describes our annual significant income tax accounting policy and related methodology. Securitizations and Variable Interest Entities We securitize, transfer, and service consumer and commercial automotive loans and operating leases. Securitization transactions typically involve the use of variable interest entities (VIEs) and are accounted for either as sales or secured borrowings. We may retain economic interests in securitized and sold assets, which are generally in the form of senior or subordinated interests, other residual interests, and servicing rights. In order to conclude whether or not a VIE is required to be consolidated, careful consideration and judgment must be given to our continuing involvement with the variable interest entity. In circumstances where we have both the power to direct the activities of the entity that most significantly impact the entity's performance and the obligation to absorb losses or the right to receive benefits of the entity that could be significant, we would conclude that we would consolidate the entity, which would also preclude us from recording an accounting sale on the transaction. In the case of a consolidated VIE, the accounting is consistent with a secured borrowing, (e.g., we continue to carry the loans and we record the related securitized debt on our Condensed Consolidated Balance Sheet ). In transactions where we are not determined to be the primary beneficiary of the VIE, we must determine whether or not we achieve a sale for accounting purposes. In order to achieve a sale for accounting purposes, the assets being transferred must be legally isolated, not be constrained by restrictions from further transfer, and be deemed to be beyond our control. If we were to fail any of the three criteria for sale accounting, the accounting would be consistent with the preceding paragraph (i.e., a secured borrowing) . Refer to Note 10 to the Condensed Consolidated Financial Statements for discussion on VIEs. Gains or losses on off-balance sheet securitizations take into consideration the fair value of any retained interests including the value of certain servicing assets or liabilities, if any, which are initially recorded at fair value at the date of sale. The estimate of the fair value of the retained interests and servicing requires us to exercise significant judgment about the timing and amount of future cash flows from the interests. Refer to Note 21 to the Condensed Consolidated Financial Statements for a discussion of fair value estimates. Gains or losses on off-balance sheet securitizations and sales are reported in gain on mortgage and automotive loans, net, in our Condensed Consolidated Statement of Comprehensive Income . Retained interests are classified as securities or as other assets depending on their nature. On December 24, 2016, the risk retention rules under the Dodd-Frank Wall Street Reform and Consumer Protection Act (Dodd-Frank Act) of 2010 became effective, requiring us to retain at least five percent of the credit risk of the assets underlying asset-backed securitizations . Our note was updated to address this guidance. We retain servicing responsibilities for all of our consumer and commercial automotive loan and operating lease securitizations. We may receive servicing fees for off-balance sheet securitizations based on the securitized loan balances and certain ancillary fees, all of which are reported in servicing fees in the Condensed Consolidated Statement of Comprehensive Income. Typically, the fee we are paid for servicing consumer automotive finance receivables represents adequate compensation, and consequently, we do not recognize a servicing asset or liability. Whether on- or off-balance sheet, the investors in the securitization trusts generally have no recourse to our assets outside of protections afforded through customary market representation and warranty repurchase provisions. Refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K regarding additional significant accounting policies. Recently Adopted Accounting Standards Stock Compensation — Improvements to Employee Share-Based Payment Accounting (ASU 2016-09) As of December 31, 2016, we adopted Accounting Standards Update (ASU) 2016-09. The amendments in this update include changes to several aspects of share-based payment accounting. The amendments allow for an entity-wide accounting policy election to either account for forfeitures as they occur or estimate the number of awards that are expected to vest. We elected to account for forfeitures as they occur. The amendments modify the tax withholding requirements to allow entities to withhold an amount up to the employee’s maximum individual statutory tax rates without resulting in a liability classification of the award as opposed to limiting the withholding to the minimum statutory tax rates as required under previous accounting guidance. The amendments require that all excess tax benefits and tax deficiencies related to share-based payment awards should be recognized in income tax expense or benefit in the income statement in the period in which they occur. The adoption of these amendments did not have a material impact to the financial statements. The amendments also address the classification and presentation of certain items on the cash flow statement. Specifically, cash flows related to excess tax benefits should be classified as an operating activity instead of a financing activity and cash flows related to cash paid to a tax authority by an employer when withholding shares from an employee’s award for tax withholding purposes should be classified as a financing activity. The adoption of the amendment requiring excess tax benefits to be classified as an operating activity did not have a material impact to our Condensed Consolidated Statement of Cash Flows . The adoption of the amendment requiring amounts paid to a tax authority by an employer when withholding shares from an employee’s award for tax withholding purposes to be classified as a financing activity resulted in the reclassification of cash flows in our Condensed Consolidated Statement of Cash Flows for the three months ended March 31, 2016 , of $14 million from operating activities to financing activities. Recently Issued Accounting Standards Revenue from Contracts with Customers (ASU 2014-09) and Revenue from Contracts with Customers — Deferral of the Effective Date (ASU 2015-14) In May 2014, the Financial Accounting Standards Board (FASB) issued ASU 2014-09. The purpose of this guidance is to streamline and consolidate existing revenue recognition principles in GAAP and to converge revenue recognition principles with International Financial Reporting Standards (IFRS). The core principle of the amendments is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to receive in exchange for those goods or services. The amendments include a five step process for consideration of the main principle, guidance on the accounting treatment for costs associated with a contract, and disclosure requirements related to the revenue process. As originally issued, the amendments in ASU 2014-09 were to be effective beginning on January 1, 2017. However, in August 2015, the FASB issued ASU 2015-14, which deferred the effective date of the guidance until January 1, 2018, and permitted early adoption as of the original effective date in ASU 2014-09. The FASB created a transition resource group to work with stakeholders and clarify the new guidance as necessary. The FASB has issued several additional ASUs to clarify guidance and provide implementation support for ASU 2014-09. The clarifying guidance elaborates on the key concepts within ASU 2014-09 and clarifies how those concepts interact with other GAAP requirements. Management has considered these additional ASUs when assessing the overall impact of ASU 2014-09. The amendments to the revenue recognition principles can be applied on adoption either through a full retrospective application or on a modified basis with a cumulative effect adjustment on the date of initial adoption with certain practical expedients. A majority of our revenue streams are not within the scope of this ASU as they are governed by other accounting standards. Management has determined that certain revenue streams and contractual arrangements are in scope of this guidance, including deposit fees, premiums on certain noninsurance contracts, brokering commissions through our insurance operations, remarketing fee income through SmartAuction, and investment advisory fee income through TradeKing. Management does not expect these amendments to impact current revenue recognition patterns for a majority of the in scope revenue streams and contracts. However, we expect that the application of this guidance to noninsurance contracts within our insurance business will result in the deferral of certain amounts we currently recognize as revenue upon the origination of the contract. We do not expect the impact of the new guidance to these specific contracts to be material to the financial statements. Management continues to evaluate whether we will adopt this guidance using the full retrospective approach or the modified retrospective approach. Financial Instruments — Recognition and Measurement of Financial Assets (ASU 2016-01) In January 2016, the FASB issued ASU 2016-01. The amendments in this update modify the requirements related to the measurement of certain financial instruments in the statement of financial condition and results of operations. For equity investments (other than investments accounted for using the equity method), entities must measure such instruments at fair value with changes in fair value recognized in net income. Changes in fair value for available-for-sale equity securities will no longer be recognized through other comprehensive income. Reporting entities may continue to elect to measure equity investments that do not have a readily determinable fair value at cost with adjustments for impairment and observable changes in price. In addition, for a liability (other than a derivative liability) that an entity measures at fair value, any change in fair value related to the instrument-specific credit risk, that is the entity’s own-credit, should be presented separately in other comprehensive income and not as a component of net income. The amendments are effective on January 1, 2018, with early adoption permitted solely for the provisions pertaining to instrument-specific credit risk for liabilities measured at fair value. The amendments must be applied on a modified retrospective basis with a cumulative effect adjustment as of the beginning of the fiscal year of initial adoption. The amendment requiring equity investments to be measured at fair value with changes in fair value recognized in net income will create additional volatility in our consolidated results of operations since changes in fair value for available-for-sale securities will be recognized in net income as opposed to other comprehensive income as required under existing accounting guidance. Management continues to evaluate the impact of the other amendments. However, we do not anticipate the other amendments to have a material impact to our financial statements. Management currently plans to adopt these amendments on January 1, 2018, and expects to use the modified retrospective approach as required. Leases (ASU 2016-02) In February 2016, the FASB issued ASU 2016-02. The amendments in this update primarily replace the existing accounting requirements for operating leases for lessees. Lessee accounting requirements for finance leases and lessor accounting requirements for both operating leases and sales type and direct financing leases (both of which were previously referred to as capital leases) are largely unchanged. The amendments require the lessee of an operating lease to record a balance sheet gross-up upon lease commencement by recognizing a right-of-use asset and lease liability equal to the present value of the lease payments. The right-of-use asset and lease liability should be derecognized in a manner that effectively yields a straight line lease expense over the lease term. In addition to the changes to the lessee operating lease accounting requirements, the amendments also change the types of costs that can be capitalized related to a lease agreement for both lessees and lessors for all types of leases. The amendments also require additional disclosures for all lease types for both lessees and lessors. The amendments are effective on January 1, 2019, with early adoption permitted. The amendments must be applied on a modified retrospective basis with a cumulative adjustment to the beginning of the earliest fiscal year presented in the financial statements in the period of adoption. Management is currently evaluating the impact of these amendments. Upon adoption, we expect to record a balance sheet gross up, reflecting our right-of-use asset and lease liability for our operating leases where we are the lessee (for example, our facility leases). We are currently reviewing our operating lease contracts where we are the lessee to determine the impact of the gross up and the changes to capitalizable costs. We are also reviewing our leases where we are the lessor to determine the impact of the changes to capitalizable costs. Management currently plans to adopt these amendments on January 1, 2019, and expects to use the modified retrospective approach as required. Financial Instruments — Credit Losses (ASU 2016-13) In June 2016, the FASB issued ASU 2016-13. The amendments in this update introduce a new accounting model to measure credit losses for financial assets measured at amortized cost. Credit losses for financial assets measured at amortized cost should be determined based on the total current expected credit losses over the life of the financial asset or group of financial assets. In effect, the financial asset or group of financial assets should be presented at the net amount expected to be collected. Credit losses will no longer be measured as they are incurred for financial assets measured at amortized cost. The amendments also modify the accounting for available-for-sale debt securities whereby credit losses will be recorded through an allowance for credit losses rather than a write-down to the security’s cost basis, which allows for reversals of credit losses when estimated credit losses decline. Credit losses for available-for-sale debt securities should be measured in a manner similar to current GAAP. The amendments are effective on January 1, 2020, with early adoption permitted as of January 1, 2019. The amendments must be applied using a modified retrospective approach with a cumulative-effect adjustment through retained earnings as of the beginning of the fiscal year upon adoption. The new accounting model for credit losses represents a significant departure from existing GAAP, and will likely materially increase the allowance for credit losses with a resulting negative adjustment to retained earnings. Management created a formal working group to govern the implementation of these amendments consisting of key stakeholders from finance, risk, and accounting and is currently evaluating the impact of the amendments. Management currently plans to adopt these amendments on January 1, 2020, and expects to use the modified retrospective approach as required. Statement of Cash Flows — Restricted Cash (ASU 2016-18) In November 2016, the FASB issued ASU 2016-18. The amendments in this update require that amounts classified as restricted cash and restricted cash equivalents be included within the beginning-of-period and end-of-period amounts along with cash and cash equivalents on the statement of cash flows. Prior to this ASU, specific guidance on the presentation of changes in restricted cash and restricted cash equivalents within the statement of cash flows did not exist. The amendments are effective on January 1, 2018, with early adoption permitted. The amendments must be applied retrospectively to all periods presented within the statement of cash flows upon adoption. Management is currently evaluating the impact of these amendments. Receivables — Nonrefundable Fees and Other Costs: Premium Amortization on Purchased Callable Debt Securities (ASU 2017-08) In March 2017, the FASB issued ASU 2017-08. The amendments in this update require premiums on purchased callable debt securities to be amortized to the security’s earliest call date. Prior to this ASU, premiums and discounts on purchased callable debt securities were generally required to be amortized to the security’s maturity date. The amendments do not require an accounting change for securities held at a discount. The amendments are effective on January 1, 2019, with early adoption permitted. The amendments must be applied using a modified retrospective approach with a cumulative-effect adjustment through retained earnings as of the beginning of the fiscal year upon adoption. Management is currently evaluating the impact of these amendments.

Acquisitions Acquisitions

Acquisitions Acquisitions	3 Months Ended
	Mar. 31, 2017
Acquisitions [Abstract]
Business Combination Disclosure [Text Block]	Acquisitions On June 1, 2016 , we acquired 100% of the equity of TradeKing Group, Inc. (TradeKing), a digital wealth management company with an online broker-dealer, digital portfolio management platform, and educational content for $298 million in cash. TradeKing, which is being rebranded as Ally Invest, operates as a wholly-owned subsidiary of Ally. The addition of brokerage and wealth management is a natural extension of our online banking franchise, creating a full suite of financial products for savings and investments. We applied the acquisition method of accounting to this transaction, which generally requires the initial recognition of assets acquired, including identifiable intangible assets, and liabilities assumed at their respective fair value. Goodwill is recognized as the excess of the acquisition price after the recognition of the net assets, including the identifiable intangible assets. Beginning in June 2016, financial information related to TradeKing is included within Corporate and Other. The following table summarizes the allocation of cash consideration paid for TradeKing and the amounts of the identifiable assets acquired and liabilities assumed recognized at the acquisition date. ($ in millions) Purchase price Cash consideration $ 298 Allocation of purchase price to net assets acquired Intangible assets (a) 82 Cash and short-term investments (b) 50 Other assets 14 Deferred tax asset, net 4 Employee compensation and benefits (41 ) Other liabilities (4 ) Goodwill $ 193 (a) We recorded $3 million of amortization on these intangible assets during the three months ended March 31, 2017. (b) Includes $40 million in cash proceeds from the acquisition transaction in order to pay employee compensation and benefits that vested upon acquisition as a result of the change in control. The goodwill of $193 million arising from the acquisition consists largely of expected growth of the business as we leverage the Ally brand and our marketing capabilities to scale the acquired technology platform and expand the suite of financial products we offer to our existing growing customer base. None of the goodwill recognized is expected to be deductible for income tax purposes. Refer to Note 12 for a reconciliation of the carrying amount of goodwill at the beginning and end of the reporting period. On August 1, 2016, we acquired assets that constitute a business from Blue Yield, an online automotive lender exchange, as we continue to expand our automotive finance offerings to include a direct-to-consumer option. We completed the acquisition for $28 million of total consideration. As a result of the purchase, we recognized $20 million of goodwill within Automotive Finance operations.

Discontinued Operations

Discontinued Operations	3 Months Ended
	Mar. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	Discontinued Operations Prior to the adoption of ASU 2014-08, which was prospectively applied only to newly identified disposals that qualify as discontinued operations beginning after January 1, 2015, we have classified operations as discontinued when operations and cash flows will be eliminated from our ongoing operations and we do not expect to retain any significant continuing involvement in their operations after the respective sale or disposal transactions. For all periods presented, the operating results for these discontinued operations have been removed from continuing operations and presented separately as discontinued operations, net of tax, in the Condensed Consolidated Statement of Comprehensive Income . The Notes to the Condensed Consolidated Financial Statements have been adjusted to exclude discontinued operations unless otherwise noted. Our discontinued operations relate to previous discontinued operations in our Automotive Finance operations, Insurance operations, and Corporate Finance operating segments, and other operations for which we continue to have wind-down, legal, and minimal operational costs. Select financial information of discontinued operations is summarized below. Three months ended March 31, ($ in millions) 2017 2016 Pretax income $ 1 $ 4 Tax expense — 1

Other Income, Net of Losses

Other Income, Net of Losses	3 Months Ended
	Mar. 31, 2017
Other Nonoperating Income (Expense) [Abstract]
Other Income and Other Expense Disclosure [Text Block]	Other Income, Net of Losses Details of other income, net of losses, were as follows. Three months ended March 31, ($ in millions) 2017 2016 Remarketing fees $ 29 $ 28 Late charges and other administrative fees 27 25 Servicing fees 16 13 Income from equity-method investments — 6 Other, net 43 23 Total other income, net of losses $ 115 $ 95

Reserves for Insurance Losses a

Reserves for Insurance Losses and Loss Adjustment Expenses Reserves for Insurance Losses and Loss Adjustment Expenses	3 Months Ended
	Mar. 31, 2017
Insurance Liability for Unpaid Claims and Claims Adjustment Expenses [Abstract]
Short-Duration Insurance and Deposit Contracts [Text Block]	Reserves for Insurance Losses and Loss Adjustment Expenses The following table shows a rollforward of our reserves for insurance losses and loss adjustment expenses. ($ in millions) 2017 2016 Total gross reserves for insurance losses and loss adjustment expenses at January 1, $ 149 $ 169 Less: Reinsurance recoverable 108 120 Net reserves for insurance losses and loss adjustment expenses at January 1, 41 49 Net insurance losses and loss adjustment expenses incurred related to: Current year 89 77 Prior years (a) (1 ) (4 ) Total net insurance losses and loss adjustment expenses incurred 88 73 Net insurance losses and loss adjustment expenses paid or payable related to: Current year (45 ) (37 ) Prior years (23 ) (22 ) Total net insurance losses and loss adjustment expenses paid or payable (68 ) (59 ) Foreign exchange and other 2 3 Net reserves for insurance losses and loss adjustment expenses at March 31, 63 66 Plus: Reinsurance recoverable 112 118 Total gross reserves for insurance losses and loss adjustment expenses at March 31, $ 175 $ 184 (a) There have been no material adverse changes to the reserve for prior years.

Other Operating Expenses

Other Operating Expenses	3 Months Ended
	Mar. 31, 2017
Operating Expenses [Abstract]
Other Operating Income and Expense [Text Block]	Other Operating Expenses Details of other operating expenses were as follows. Three months ended March 31, ($ in millions) 2017 2016 Insurance commissions $ 99 $ 94 Technology and communications 69 66 Lease and loan administration 36 32 Advertising and marketing 30 27 Vehicle remarketing and repossession 28 24 Regulatory and licensing fees 27 21 Professional services 26 24 Premises and equipment depreciation 22 21 Occupancy 12 13 Non-income taxes 8 9 Other 48 54 Total other operating expenses $ 405 $ 385

Investment Securities

Investment Securities	3 Months Ended
	Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]	Investment Securities Our portfolio of securities includes bonds, equity securities, asset-backed securities, commercial and residential mortgage-backed securities, and other investments. The cost, fair value, and gross unrealized gains and losses on investment securities were as follows. March 31, 2017 December 31, 2016 Amortized cost Gross unrealized Fair value Amortized cost Gross unrealized Fair ($ in millions) gains losses gains losses Available-for-sale securities Debt securities U.S. Treasury $ 2,276 $ 1 $ (52 ) $ 2,225 $ 1,680 $ — $ (60 ) $ 1,620 U.S. States and political subdivisions 803 9 (17 ) 795 794 7 (19 ) 782 Foreign government 143 3 — 146 157 5 — 162 Agency mortgage-backed residential 12,054 31 (223 ) 11,862 10,473 29 (212 ) 10,290 Mortgage-backed residential 2,053 4 (61 ) 1,996 2,162 5 (70 ) 2,097 Mortgage-backed commercial 533 2 (1 ) 534 537 2 (2 ) 537 Asset-backed 1,046 6 (1 ) 1,051 1,396 6 (2 ) 1,400 Corporate debt 1,262 6 (13 ) 1,255 1,452 7 (16 ) 1,443 Total debt securities (a) (b) 20,170 62 (368 ) 19,864 18,651 61 (381 ) 18,331 Equity securities 481 9 (46 ) 444 642 7 (54 ) 595 Total available-for-sale securities $ 20,651 $ 71 $ (414 ) $ 20,308 $ 19,293 $ 68 $ (435 ) $ 18,926 Held-to-maturity securities Debt securities Agency mortgage-backed residential (c) $ 1,052 $ 2 $ (43 ) $ 1,011 $ 839 $ — $ (50 ) $ 789 Asset-backed retained notes 52 — — 52 — — — — Total held-to-maturity securities (d) $ 1,104 $ 2 $ (43 ) $ 1,063 $ 839 $ — $ (50 ) $ 789 (a) Certain entities related to our Insurance operations are required to deposit securities with state regulatory authorities. These deposited securities totaled $12 million and $14 million at March 31, 2017 , and December 31, 2016 , respectively. (b) Investment securities with a fair value of $3,235 million and $4,881 million at March 31, 2017 , and December 31, 2016 , respectively, were pledged to secure advances from the Federal Home Loan Bank (FHLB), short-term borrowings or repurchase agreements and for other purposes as required by contractual obligation or law. Under these agreements, Ally has granted the counterparty the right to sell or pledge $1,257 million and $737 million of the underlying investment securities at March 31, 2017 , and December 31, 2016 , respectively. (c) Agency-backed residential mortgage-backed debt securities are held for liquidity purposes. (d) Held-to-maturity securities are recorded at amortized cost. Held-to-maturity securities with a fair value of $0 million and $87 million at March 31, 2017, and December 31, 2016 , respectively, were pledged to secure advances from the FHLB. The maturity distribution of investment securities outstanding is summarized in the following tables. Call or prepayment options may cause actual maturities to differ from contractual maturities. Total Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years ($ in millions) Amount Yield Amount Yield Amount Yield Amount Yield Amount Yield March 31, 2017 Fair value of available-for-sale debt securities (a) U.S. Treasury $ 2,225 1.8 % $ — — % $ 262 1.8 % $ 1,963 1.8 % $ — — % U.S. States and political subdivisions 795 3.1 66 2.4 34 2.5 175 2.9 520 3.3 Foreign government 146 2.5 — — 66 2.7 80 2.4 — — Agency mortgage-backed residential 11,862 3.0 — — — — 3 2.9 11,859 3.0 Mortgage-backed residential 1,996 2.9 — — — — — — 1,996 2.9 Mortgage-backed commercial 534 2.8 — — — — 3 2.8 531 2.8 Asset-backed 1,051 2.9 — — 829 2.9 59 3.2 163 2.6 Corporate debt 1,255 2.9 99 2.1 642 2.6 468 3.2 46 4.7 Total available-for-sale debt securities $ 19,864 2.8 $ 165 2.2 $ 1,833 2.6 $ 2,751 2.2 $ 15,115 3.0 Amortized cost of available-for-sale debt securities $ 20,170 $ 165 $ 1,826 $ 2,806 $ 15,373 Amortized cost of held-to-maturity securities Agency mortgage-backed residential 1,052 3.0 % — — % — — % — — % 1,052 3.0 % Asset-backed retained notes 52 1.5 10 0.8 40 1.6 2 2.7 — — Total held-to-maturity securities $ 1,104 2.9 $ 10 0.8 $ 40 1.6 $ 2 2.7 $ 1,052 3.0 December 31, 2016 Fair value of available-for-sale debt securities (a) U.S. Treasury $ 1,620 1.7 % $ 2 4.6 % $ 60 1.6 % $ 1,558 1.7 % $ — — % U.S. States and political subdivisions 782 3.1 64 1.7 29 2.3 172 2.8 517 3.4 Foreign government 162 2.6 — — 58 2.8 104 2.4 — — Agency mortgage-backed residential 10,290 2.9 — — — — 29 2.6 10,261 2.9 Mortgage-backed residential 2,097 2.9 — — — — — — 2,097 2.9 Mortgage-backed commercial 537 2.6 — — — — 3 2.8 534 2.6 Asset-backed 1,400 2.8 — — 1,059 2.8 143 3.2 198 2.6 Corporate debt 1,443 2.8 72 2.2 840 2.6 489 3.2 42 4.7 Total available-for-sale debt securities $ 18,331 2.8 $ 138 2.0 $ 2,046 2.7 $ 2,498 2.2 $ 13,649 2.9 Amortized cost of available-for-sale debt securities $ 18,651 $ 138 $ 2,040 $ 2,563 $ 13,910 Amortized cost of held-to-maturity securities $ 839 2.9 % $ — — % $ — — % $ — — % $ 839 2.9 % (a) Yield is calculated using the effective yield of each security at the end of the period, weighted based on the market value. The effective yield considers the contractual coupon and amortized cost, and excludes expected capital gains and losses. The balances of cash equivalents were $1.1 billion and $291 million at March 31, 2017 , and December 31, 2016 , respectively, and were composed primarily of money market accounts and short-term securities, including U.S. Treasury bills. The following table presents interest and dividends on investment securities. Three months ended March 31, ($ in millions) 2017 2016 Taxable interest $ 119 $ 94 Taxable dividends 2 4 Interest and dividends exempt from U.S. federal income tax 5 4 Interest and dividends on investment securities $ 126 $ 102 Gross gains realized upon the sales of available-for-sale securities were $27 million and $54 million for the three months ended March 31, 2017 , and 2016, respectively. There were no gross realized losses or other-than-temporary impairments upon the sales of available-for-sale securities for either period. The table below summarizes available-for-sale securities in an unrealized loss position in accumulated other comprehensive income. Based on the assessment of whether such losses were deemed to be other-than-temporary, we believe that the unrealized losses are not indicative of an other-than-temporary impairment of these securities. As of March 31, 2017 , we did not have the intent to sell the debt securities with an unrealized loss position in accumulated other comprehensive income, it is not more likely than not that we will be required to sell these securities before recovery of their amortized cost basis, and we expect to recover the entire amortized cost basis of the securities. As of March 31, 2017 , we had the ability and intent to hold equity securities with an unrealized loss position in accumulated other comprehensive income, and it is not more likely than not that we will be required to sell these securities before recovery of their amortized cost basis. As a result, we believe that the securities with an unrealized loss position in accumulated other comprehensive income are not considered to be other-than-temporarily impaired at March 31, 2017 . Refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K for additional information related to investment securities and our methodology for evaluating potential other-than-temporary impairments. March 31, 2017 December 31, 2016 Less than 12 months 12 months or longer Less than 12 months 12 months or longer $ in millions) Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss Available-for-sale securities Debt securities U.S. Treasury $ 2,070 $ (52 ) $ — $ — $ 1,612 $ (60 ) $ — $ — U.S. States and political subdivisions 435 (16 ) 26 (1 ) 524 (19 ) — — Foreign government 13 — — — 38 — — — Agency mortgage-backed residential 8,874 (209 ) 531 (14 ) 8,052 (196 ) 587 (16 ) Mortgage-backed residential 768 (16 ) 816 (45 ) 813 (17 ) 860 (53 ) Mortgage-backed commercial 79 (1 ) 77 — 47 (1 ) 149 (1 ) Asset-backed 175 — 134 (1 ) 375 (2 ) 127 — Corporate debt 565 (11 ) 46 (2 ) 744 (14 ) 46 (2 ) Total temporarily impaired debt securities 12,979 (305 ) 1,630 (63 ) 12,205 (309 ) 1,769 (72 ) Temporarily impaired equity securities 72 (6 ) 162 (40 ) 151 (8 ) 269 (46 ) Total temporarily impaired available-for-sale securities $ 13,051 $ (311 ) $ 1,792 $ (103 ) $ 12,356 $ (317 ) $ 2,038 $ (118 )

Finance Receivables and Loans,

Finance Receivables and Loans, Net	3 Months Ended
	Mar. 31, 2017
Loans and Leases Receivable, Net Amount [Abstract]
Loans, Notes, Trade and Other Receivables Disclosure [Text Block]	Finance Receivables and Loans, Net The composition of finance receivables and loans reported at gross carrying value was as follows. ($ in millions) March 31, 2017 December 31, 2016 Consumer automotive (a) $ 65,663 $ 65,793 Consumer mortgage Mortgage Finance (b) 8,331 8,294 Mortgage — Legacy (c) 2,606 2,756 Total consumer mortgage 10,937 11,050 Total consumer 76,600 76,843 Commercial Commercial and industrial Automotive 34,911 35,041 Other 3,499 3,248 Commercial real estate — Automotive 3,992 3,812 Total commercial 42,402 42,101 Total finance receivables and loans (d) $ 119,002 $ 118,944 (a) Includes $34 million and $43 million of fair value adjustment for loans in hedge accounting relationships at March 31, 2017 , and December 31, 2016 , respectively. Refer to Note 19 for additional information. (b) Includes loans originated as interest-only mortgage loans of $26 million and $30 million at March 31, 2017 , and December 31, 2016 , respectively, 3% of which are expected to start principal amortization in 2017 , none in 2018 , 37% in 2019 , 42% in 2020 , and none thereafter. (c) Includes loans originated as interest-only mortgage loans of $653 million and $714 million at March 31, 2017 , and December 31, 2016 , respectively, 17% of which are expected to start principal amortization in 2017 , 2% in 2018 , none in 2019 , none in 2020 , and 1% thereafter. (d) Totals include net increases of $393 million and $359 million at March 31, 2017 , and December 31, 2016 , respectively, for unearned income, unamortized premiums and discounts, and deferred fees and costs. The following tables present an analysis of the activity in the allowance for loan losses on finance receivables and loans. Three months ended March 31, 2017 ($ in millions) Consumer automotive Consumer mortgage Commercial Total Allowance at January 1, 2017 $ 932 $ 91 $ 121 $ 1,144 Charge-offs (a) (341 ) (9 ) — (350 ) Recoveries 90 7 — 97 Net charge-offs (251 ) (2 ) — (253 ) Provision for loan losses 267 (3 ) 7 271 Other (b) (7 ) — — (7 ) Allowance at March 31, 2017 $ 941 $ 86 $ 128 $ 1,155 Allowance for loan losses at March 31, 2017 Individually evaluated for impairment $ 32 $ 33 $ 24 $ 89 Collectively evaluated for impairment 909 53 104 1,066 Finance receivables and loans at gross carrying value Ending balance $ 65,663 $ 10,937 $ 42,402 $ 119,002 Individually evaluated for impairment 388 249 120 757 Collectively evaluated for impairment 65,275 10,688 42,282 118,245 (a) Represents the amount of the gross carrying value directly written-off. For consumer and commercial loans, the loss from a charge-off is measured as the difference between the gross carrying value of a loan and the fair value of the collateral, less costs to sell. Refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K for more information regarding our charge-off policies. (b) Primarily related to the transfer of finance receivables and loans from held-for-investment to held-for-sale. Three months ended March 31, 2016 ($ in millions) Consumer automotive Consumer mortgage Commercial Total Allowance at January 1, 2016 $ 834 $ 114 $ 106 $ 1,054 Charge-offs (a) (253 ) (10 ) — (263 ) Recoveries 80 4 — 84 Net charge-offs (173 ) (6 ) — (179 ) Provision for loan losses 207 7 6 220 Other (b) (18 ) — — (18 ) Allowance at March 31, 2016 $ 850 $ 115 $ 112 $ 1,077 Allowance for loan losses at March 31, 2016 Individually evaluated for impairment $ 25 $ 43 $ 18 $ 86 Collectively evaluated for impairment 825 72 94 991 Finance receivables and loans at gross carrying value Ending balance $ 63,013 $ 10,675 $ 37,188 $ 110,876 Individually evaluated for impairment 337 261 90 688 Collectively evaluated for impairment 62,676 10,414 37,098 110,188 (a) Represents the amount of the gross carrying value directly written-off. For consumer and commercial loans, the loss from a charge-off is measured as the difference between the gross carrying value of a loan and the fair value of the collateral, less costs to sell. Refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K for more information regarding our charge-off policies. (b) Primarily related to the transfer of finance receivables and loans from held-for-investment to held-for-sale. The following table presents information about significant sales of finance receivables and loans and transfers of finance receivables and loans from held-for-investment to held-for-sale. Three months ended March 31, ($ in millions) 2017 2016 Consumer automotive $ 1,213 $ 2,599 Consumer mortgage 3 2 Total sales and transfers $ 1,216 $ 2,601 The following table presents information about significant purchases of finance receivables and loans. Three months ended March 31, ($ in millions) 2017 2016 Consumer automotive $ 68 $ — Consumer mortgage 327 1,370 Total purchases of finance receivables and loans $ 395 $ 1,370 The following table presents an analysis of our past due finance receivables and loans recorded at gross carrying value. ($ in millions) 30–59 days past due 60–89 days past due 90 days or more past due Total past due Current Total finance receivables and loans March 31, 2017 Consumer automotive $ 1,346 $ 308 $ 263 $ 1,917 $ 63,746 $ 65,663 Consumer mortgage Mortgage Finance 30 2 7 39 8,292 8,331 Mortgage — Legacy 33 14 57 104 2,502 2,606 Total consumer mortgage 63 16 64 143 10,794 10,937 Total consumer 1,409 324 327 2,060 74,540 76,600 Commercial Commercial and industrial Automotive — — 6 6 34,905 34,911 Other — — — — 3,499 3,499 Commercial real estate — Automotive — — — — 3,992 3,992 Total commercial — — 6 6 42,396 42,402 Total consumer and commercial $ 1,409 $ 324 $ 333 $ 2,066 $ 116,936 $ 119,002 December 31, 2016 Consumer automotive $ 1,850 $ 428 $ 302 $ 2,580 $ 63,213 $ 65,793 Consumer mortgage Mortgage Finance 39 6 4 49 8,245 8,294 Mortgage — Legacy 45 18 57 120 2,636 2,756 Total consumer mortgage 84 24 61 169 10,881 11,050 Total consumer 1,934 452 363 2,749 74,094 76,843 Commercial Commercial and industrial Automotive 3 — 7 10 35,031 35,041 Other — — — — 3,248 3,248 Commercial real estate — Automotive — — — — 3,812 3,812 Total commercial 3 — 7 10 42,091 42,101 Total consumer and commercial $ 1,937 $ 452 $ 370 $ 2,759 $ 116,185 $ 118,944 The following table presents the gross carrying value of our finance receivables and loans on nonaccrual status. ($ in millions) March 31, 2017 December 31, 2016 Consumer automotive $ 573 $ 598 Consumer mortgage Mortgage Finance 10 10 Mortgage — Legacy 95 89 Total consumer mortgage 105 99 Total consumer 678 697 Commercial Commercial and industrial Automotive 34 33 Other 81 84 Commercial real estate — Automotive 5 5 Total commercial 120 122 Total consumer and commercial finance receivables and loans $ 798 $ 819 Management performs a quarterly analysis of the consumer automotive, consumer mortgage, and commercial portfolios using a range of credit quality indicators to assess the adequacy of the allowance for loan losses based on historical and current trends. The following tables present the population of loans by quality indicators for our consumer automotive, consumer mortgage, and commercial portfolios. The following table presents performing and nonperforming credit quality indicators in accordance with our internal accounting policies for our consumer finance receivables and loans recorded at gross carrying value. Nonperforming loans include finance receivables and loans on nonaccrual status when the principal or interest has been delinquent for 90 days or when full collection is not expected. Refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K for additional information. March 31, 2017 December 31, 2016 ($ in millions) Performing Nonperforming Total Performing Nonperforming Total Consumer automotive $ 65,090 $ 573 $ 65,663 $ 65,195 $ 598 $ 65,793 Consumer mortgage Mortgage Finance 8,321 10 8,331 8,284 10 8,294 Mortgage — Legacy 2,511 95 2,606 2,667 89 2,756 Total consumer mortgage 10,832 105 10,937 10,951 99 11,050 Total consumer $ 75,922 $ 678 $ 76,600 $ 76,146 $ 697 $ 76,843 The following table presents pass and criticized credit quality indicators based on regulatory definitions for our commercial finance receivables and loans recorded at gross carrying value. March 31, 2017 December 31, 2016 ($ in millions) Pass Criticized (a) Total Pass Criticized (a) Total Commercial and industrial Automotive $ 32,878 $ 2,033 $ 34,911 $ 33,160 $ 1,881 $ 35,041 Other 2,814 685 3,499 2,597 651 3,248 Commercial real estate — Automotive 3,816 176 3,992 3,653 159 3,812 Total commercial $ 39,508 $ 2,894 $ 42,402 $ 39,410 $ 2,691 $ 42,101 (a) Includes loans classified as special mention, substandard, or doubtful. These classifications are based on regulatory definitions and generally represent loans within our portfolio that have a higher default risk or have already defaulted. Impaired Loans and Troubled Debt Restructurings Impaired Loans Loans are considered impaired when we determine it is probable that we will be unable to collect all amounts due according to the terms of the loan agreement. For more information on our impaired finance receivables and loans, refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K. The following table presents information about our impaired finance receivables and loans. ( $ in millions ) Unpaid principal balance (a) Gross carrying value Impaired with no allowance Impaired with an allowance Allowance for impaired loans March 31, 2017 Consumer automotive $ 422 $ 388 $ 124 $ 264 $ 32 Consumer mortgage Mortgage Finance 8 8 4 4 — Mortgage — Legacy 245 241 56 185 33 Total consumer mortgage 253 249 60 189 33 Total consumer 675 637 184 453 65 Commercial Commercial and industrial Automotive 34 34 7 27 2 Other 98 81 19 62 21 Commercial real estate — Automotive 5 5 — 5 1 Total commercial 137 120 26 94 24 Total consumer and commercial finance receivables and loans $ 812 $ 757 $ 210 $ 547 $ 89 December 31, 2016 Consumer automotive $ 407 $ 370 $ 131 $ 239 $ 28 Consumer mortgage Mortgage Finance 8 8 3 5 — Mortgage — Legacy 243 239 56 183 34 Total consumer mortgage 251 247 59 188 34 Total consumer 658 617 190 427 62 Commercial Commercial and industrial Automotive 33 33 7 26 3 Other 99 84 — 84 19 Commercial real estate — Automotive 5 5 2 3 1 Total commercial 137 122 9 113 23 Total consumer and commercial finance receivables and loans $ 795 $ 739 $ 199 $ 540 $ 85 (a) Adjusted for charge-offs. The following table presents average balance and interest income for our impaired finance receivables and loans. 2017 2016 Three months ended March 31, ($ in millions) Average balance Interest income Average balance Interest income Consumer automotive $ 379 $ 5 $ 326 $ 4 Consumer mortgage Mortgage Finance 8 — 9 — Mortgage — Legacy 241 2 255 2 Total consumer mortgage 249 2 264 2 Total consumer 628 7 590 6 Commercial Commercial and industrial Automotive 33 — 23 — Other 83 — 49 1 Commercial real estate — Automotive 5 — 6 — Total commercial 121 — 78 1 Total consumer and commercial finance receivables and loans $ 749 $ 7 $ 668 $ 7 Troubled Debt Restructurings Troubled Debt Restructurings (TDRs) are loan modifications where concessions were granted to borrowers experiencing financial difficulties. For automotive loans, we may offer several types of assistance to aid our customers, including extension of the loan maturity date and rewriting the loan terms. Additionally, for mortgage loans, as part of certain programs, we offer mortgage loan modifications to qualified borrowers. Numerous initiatives are in place to provide support to our mortgage customers in financial distress, including principal forgiveness, maturity extensions, delinquent interest capitalization, and changes to contractual interest rates. Total TDRs recorded at gross carrying value were $704 million and $663 million at March 31, 2017 , and December 31, 2016 , respectively. Commercial commitments to lend additional funds to borrowers whose terms had been modified in a TDR were $3 million and $2 million at March 31, 2017 , and December 31, 2016 , respectively. Refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K for additional information. The following table presents information related to finance receivables and loans recorded at gross carrying value modified in connection with a TDR during the period. 2017 2016 Three months ended March 31, ($ in millions) Number of loans Pre-modification gross carrying value Post-modification gross carrying value Number of loans Pre-modification gross carrying value Post-modification gross carrying value Consumer automotive 6,447 $ 115 $ 99 5,622 $ 89 $ 76 Consumer mortgage Mortgage Finance 1 — — 1 1 1 Mortgage — Legacy 53 12 12 31 4 4 Total consumer mortgage 54 12 12 32 5 5 Total consumer 6,501 127 111 5,654 94 81 Commercial Commercial and industrial Automotive — — — — — — Other 1 23 23 — — — Commercial real estate — Automotive — — — — — — Total commercial 1 23 23 — — — Total consumer and commercial finance receivables and loans 6,502 $ 150 $ 134 5,654 $ 94 $ 81 The following table presents information about finance receivables and loans recorded at gross carrying value that have redefaulted during the reporting period and were within 12 months or less of being modified as a TDR. Redefault is when finance receivables and loans meet the requirements for evaluation under our charge-off policy (refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K for additional information) except for commercial finance receivables and loans, where redefault is defined as 90 days past due. 2017 2016 Three months ended March 31, ($ in millions) Number of loans Gross carrying value Charge-off amount Number of loans Gross carrying value Charge-off amount Consumer automotive 1,989 $ 24 $ 16 1,800 $ 23 $ 12 Consumer mortgage Mortgage Finance 1 1 — — — — Mortgage — Legacy — — — 1 — — Total consumer finance receivables and loans 1,990 $ 25 $ 16 1,801 $ 23 $ 12

Investment in Operating Leases,

Investment in Operating Leases, Net	3 Months Ended
	Mar. 31, 2017
Leases, Operating [Abstract]
Operating Leases of Lessor Disclosure [Text Block]	Investment in Operating Leases, Net Investments in operating leases were as follows. ($ in millions) March 31, 2017 December 31, 2016 Vehicles $ 13,240 $ 14,584 Accumulated depreciation (2,779 ) (3,114 ) Investment in operating leases, net $ 10,461 $ 11,470 Depreciation expense on operating lease assets includes remarketing gains and losses recognized on the sale of operating lease assets. The following summarizes the components of depreciation expense on operating lease assets. Three months ended March 31, ($ in millions) 2017 2016 Depreciation expense on operating lease assets (excluding remarketing gains and losses) $ 386 $ 565 Remarketing losses (gains) 3 (55 ) Net depreciation expense on operating lease assets $ 389 $ 510

Securitizations and Variable In

Securitizations and Variable Interest Entities	3 Months Ended
	Mar. 31, 2017
Securitizations And Variable Interest Entities [Abstract]
Variable Interest Entity Disclosure [Text Block]	Securitizations and Variable Interest Entities We are involved in several types of securitization and financing transactions that utilize special-purpose entities (SPEs). A SPE is an entity that is designed to fulfill a specified limited need of the sponsor. Our principal use of SPEs is to obtain liquidity by securitizing certain of our financial assets and operating lease assets. The transaction-specific SPEs involved in our securitization and other financing transactions are often considered VIEs. VIEs are entities that have either a total equity investment at risk that is insufficient to permit the entity to finance its activities without additional subordinated financial support or whose equity investors at risk lack the ability to control the entity's activities. We provide a wide range of consumer and commercial automotive loans, operating leases, and commercial loans to a diverse customer base. We securitize consumer and commercial automotive loans, and operating leases through private-label securitizations. We often securitize these loans and notes secured by operating leases (collectively referred to as financial assets) through the use of securitization entities, which may or may not be consolidated on our Condensed Consolidated Balance Sheet. The pretax gain on sales of financial assets into nonconsolidated consumer automotive securitization trusts was $2 million for the three months ended March 31, 2017 . There was no pretax gain or loss for the three months ended March 31, 2016 . We provide long-term guarantee contracts to investors in certain nonconsolidated affordable housing entities and have extended a line of credit to provide liquidity. Since we do not have control over the entities or the power to make decisions, we do not consolidate the entities and our involvement is limited to the guarantee and the line of credit. We have involvement with various other nonconsolidated equity investments, including affordable housing entities and venture capital funds and loan funds. We do not consolidate these entities and our involvement is limited to our outstanding investment, additional capital committed to these funds plus any previously recognized low income housing tax credits that are subject to recapture. Refer to Note 11 to the Consolidated Financial Statements included in our 2016 Annual Report on Form 10-K for further description of our securitization activities and our involvement with VIEs. The following table presents our involvement in consolidated and nonconsolidated VIEs in which we hold variable interests. For additional detail related to the assets and liabilities of consolidated variable interest entities refer to the Condensed Consolidated Balance Sheet. ($ in millions) Carrying value of total assets Carrying value of total liabilities Assets sold to Maximum exposure to March 31, 2017 On-balance sheet variable interest entities Consumer automotive $ 19,632 (b) $ 8,298 (c) Commercial automotive 14,113 5,109 Off-balance sheet variable interest entities Consumer automotive 79 (d) — $ 3,571 $ 3,650 (e) Commercial other 505 (f) 205 (g) — 695 (h) Total $ 34,329 $ 13,612 $ 3,571 $ 4,345 December 31, 2016 On-balance sheet variable interest entities Consumer automotive $ 20,869 (b) $ 8,557 (c) Commercial automotive 16,278 4,764 Off-balance sheet variable interest entities Consumer automotive 24 (d) — $ 2,899 $ 2,923 (e) Commercial other 460 (f) 169 (g) — 651 (h) Total $ 37,631 $ 13,490 $ 2,899 $ 3,574 (a) Asset values represent the current unpaid principal balance of outstanding consumer finance receivables and loans within the VIEs. (b) Includes $9.2 billion and $9.6 billion of assets that are not encumbered by VIE beneficial interests held by third parties at March 31, 2017 , and December 31, 2016 , respectively. Ally or consolidated affiliates hold the interests in these assets, which eliminate in consolidation. (c) Includes $64 million and $50 million of liabilities due to consolidated affiliates at March 31, 2017 , and December 31, 2016 , respectively. These liabilities are not obligations to third-party beneficial interest holders. These liabilities are secured by a portion of the unencumbered assets and eliminate in consolidation. (d) Includes $52 million classified as held-to-maturity securities and $27 million classified as other assets at March 31, 2017 . Of the total amount at March 31, 2017 , $53 million represents retained notes and certificated residual interests. These assets represent our compliance with the risk retention rules under the Dodd-Frank Act, requiring us to retain at least five percent of the credit risk of the assets underlying asset-backed securitizations , which became effective on December 24, 2016. Amounts at December 31, 2016 , are classified as other assets. (e) Maximum exposure to loss represents the current unpaid principal balance of outstanding loans, retained notes, certificated residual interests, as well as certain noncertificated interests retained from the sale of automotive finance receivables. This measure is based on the very unlikely event that all of our sold loans have defects that would trigger a representation and warranty provision and the underlying collateral supporting the loans becomes worthless. This required disclosure is not an indication of our expected loss. (f) Amounts are classified as other assets. (g) Amounts are classified as accrued expenses and other liabilities. (h) For certain nonconsolidated affordable housing entities, maximum exposure to loss represents the yield we guaranteed investors through long-term guarantee contracts. The amount disclosed is based on the unlikely event that the underlying properties cease generating yield to investors and the yield delivered to investors in the form of low income tax housing credits is recaptured. For nonconsolidated equity investments, maximum exposure to loss represents our outstanding investment, additional committed capital, and low income housing tax credits subject to recapture. The amount disclosed is based on the unlikely event that our committed capital is funded, our investments become worthless, and the tax credits previously delivered to us are recaptured. This required disclosure is not an indication of our expected loss. Cash Flows with Off-balance Sheet Securitization Entities The following table summarizes cash flows received and paid related to securitization entities and asset-backed financings where the transfer is accounted for as a sale and we have a continuing involvement with the transferred assets (e.g., servicing) that were outstanding during the three months ended March 31, 2017 , and 2016 . Additionally, this table contains information regarding cash flows received from and paid to nonconsolidated securitization entities that existed during each period. Three months ended March 31, ($ in millions) Consumer automotive 2017 Cash proceeds from transfers completed during the period $ 1,138 Servicing fees 9 Other cash flows 2 2016 Cash proceeds from transfers completed during the period $ 1,025 Servicing fees 8 Other cash flows 2 Delinquencies and Net Credit Losses The following tables represent on-balance sheet loans held-for-sale and finance receivables and loans, off-balance sheet securitizations, and whole-loan sales where we have continuing involvement. The tables present quantitative information about delinquencies and net credit losses. Total Amount Amount 60 days or more ($ in millions) March 31, 2017 December 31, 2016 March 31, 2017 December 31, 2016 On-balance sheet loans Consumer automotive $ 65,663 $ 65,793 $ 571 $ 730 Consumer mortgage 10,938 11,050 80 85 Commercial automotive 38,903 38,853 6 7 Commercial other 3,499 3,248 — — Total on-balance sheet loans 119,003 118,944 657 822 Off-balance sheet securitization entities Consumer automotive 3,067 2,392 12 13 Total off-balance sheet securitization entities 3,067 2,392 12 13 Whole-loan sales (a) 2,787 3,164 5 6 Total $ 124,857 $ 124,500 $ 674 $ 841 (a) Whole-loan sales are not part of a securitization transaction, but represent consumer automotive pools of loans sold to third-party investors. Net credit losses Three months ended March 31, ($ in millions) 2017 2016 On-balance sheet loans Consumer automotive $ 251 $ 173 Consumer mortgage 2 6 Total on-balance sheet loans 253 179 Off-balance sheet securitization entities Consumer automotive 3 2 Total off-balance sheet securitization entities 3 2 Whole-loan sales (a) 1 — Total $ 257 $ 181 (a) Whole-loan sales are not part of a securitization transaction, but represent consumer automotive pools of loans sold to third-party investors.

Servicing Activities

Servicing Activities	3 Months Ended
	Mar. 31, 2017
Servicing Asset [Abstract]
Servicing Activities [Text Block]	Servicing Activities Automotive Finance Servicing Activities We service consumer automotive contracts. Historically, we have sold a portion of our consumer automotive contracts. With respect to contracts we sell, we generally retain the right to service and earn a servicing fee for our servicing function. We have concluded that the fee we are paid for servicing consumer automotive finance receivables represents adequate compensation, and consequently, we do not recognize a servicing asset or liability. We recognized automotive servicing fee income of $16 million and $13 million during the three months ended March 31, 2017 , and 2016 , respectively. Automotive Finance Serviced Assets The current unpaid principal balance and any related unamortized deferred fees and costs of total serviced automotive finance loans and leases outstanding were as follows. ($ in millions) March 31, 2017 December 31, 2016 On-balance sheet automotive finance loans and leases Consumer automotive $ 65,464 $ 65,646 Commercial automotive 38,903 38,853 Operating leases 10,332 11,311 Other 67 67 Off-balance sheet automotive finance loans Securitizations 3,103 2,412 Whole-loan 2,824 3,191 Total serviced automotive finance loans and leases $ 120,693 $ 121,480

Other Assets

Other Assets	3 Months Ended
	Mar. 31, 2017
Other Assets [Abstract]
Other Assets Disclosure [Text Block]	Other Assets The components of other assets were as follows. ($ in millions) March 31, 2017 December 31, 2016 Property and equipment at cost $ 939 $ 901 Accumulated depreciation (542 ) (525 ) Net property and equipment 397 376 Restricted cash collections for securitization trusts (a) 1,359 1,694 Net deferred tax assets 900 994 Nonmarketable equity investments (b) 833 1,046 Accrued interest and rent receivables 457 476 Goodwill (c) 240 240 Other accounts receivable 165 100 Cash reserve deposits held-for-securitization trusts (d) 164 184 Cash collateral placed with counterparties 119 167 Restricted cash and cash equivalents 111 111 Fair value of derivative contracts in receivable position (e) 80 95 Other assets 1,309 1,371 Total other assets $ 6,134 $ 6,854 (a) Represents cash collections from customer payments on securitized receivables. These funds are distributed to investors as payments on the related secured debt. (b) Includes investments in FHLB stock of $359 million and $577 million at March 31, 2017 , and December 31, 2016 , respectively; and Federal Reserve Bank (FRB) stock of $435 million at both March 31, 2017 , and December 31, 2016 . (c) Includes goodwill of $27 million at our Insurance operations at both March 31, 2017 , and December 31, 2016 ; $193 million within Corporate and Other at both March 31, 2017 , and December 31, 2016 ; and $20 million within Automotive Finance operations at both March 31, 2017 , and December 31, 2016 . No changes to the carrying amount of goodwill were recorded during the three months ended March 31, 2017 . (d) Represents credit enhancement in the form of cash reserves for various securitization transactions. (e) For additional information on derivative instruments and hedging activities, refer to Note 19 .

Deposit Liabilities

Deposit Liabilities	3 Months Ended
	Mar. 31, 2017
Deposits [Abstract]
Deposit Liabilities Disclosures [Text Block]	Deposit Liabilities Deposit liabilities consisted of the following. ( $ in millions ) March 31, 2017 December 31, 2016 Noninterest-bearing deposits $ 102 $ 84 Interest-bearing deposits Savings and money market checking accounts 51,150 46,976 Certificates of deposit 33,148 31,795 Dealer deposits 86 167 Total deposit liabilities $ 84,486 $ 79,022 At March 31, 2017 , and December 31, 2016 , certificates of deposit included $12.2 billion and $12.1 billion , respectively, of certificates of deposit in denominations of $100 thousand or more. At both March 31, 2017 , and December 31, 2016 , certificates of deposit included $3.5 billion in denominations in excess of $250 thousand federal insurance limits.

Debt

Debt	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Debt Disclosure [Text Block]	Debt Short-term Borrowings The following table presents the composition of our short-term borrowings portfolio. March 31, 2017 December 31, 2016 ($ in millions) Unsecured Secured (a) Total Unsecured Secured (a) Total Demand notes $ 3,652 $ — $ 3,652 $ 3,622 $ — $ 3,622 Federal Home Loan Bank — 1,850 1,850 — 7,875 7,875 Financial instruments sold under agreements to repurchase — 1,620 1,620 — 1,176 1,176 Other 1,249 (b) — 1,249 — — — Total short-term borrowings $ 4,901 $ 3,470 $ 8,371 $ 3,622 $ 9,051 $ 12,673 (a) Refer to the section below titled Long-term Debt for further details on assets restricted as collateral for payment of the related debt. (b) Balance represents private unsecured committed credit facility and includes debt issuance costs of $1 million as of March 31, 2017 . This debt is scheduled to mature in December 2017. We periodically enter into term repurchase agreements, short-term borrowing agreements in which we sell financial instruments to one or more investors while simultaneously committing to repurchase them at a specified future date, at the stated price plus accrued interest. As of March 31, 2017 , the financial instruments sold under agreement to repurchase consisted of $520 million of mortgage-backed residential securities maturing within the next 30 days , $0 million within 31 to 60 days, and $626 million within 61 to 90 days. For further details refer to Note 7 and Note 22 . Additionally, in December 2016, we sold asset-backed automotive financial instruments, which are our retained interests from certain on-balance sheet securitizations, subject to a repurchase agreement set to mature by July 2017 in exchange for $500 million , which was recorded as a short-term secured borrowing. As of March 31, 2017, the balance was $474 million . The asset-backed automotive financial instruments that we sold subject to the repurchase agreement are secured by finance receivables that we have securitized. Refer to Note 10 for additional information on our securitization activities. The primary risk associated with these repurchase agreements is that the counterparty will be unable to perform under the terms of the contract. As the borrower, we are exposed to the excess market value of the securities pledged over the amount borrowed. Daily mark-to-market collateral management is designed to limit this risk to the initial margin. However, should a counterparty declare bankruptcy or become insolvent, we may incur additional delays and costs. As of March 31, 2017 , we received cash collateral totaling $1 million and we placed cash collateral totaling $5 million with counterparties under these collateral arrangements associated with our repurchase agreements. Long-term Debt The following table presents the composition of our long-term debt portfolio. March 31, 2017 December 31, 2016 ($ in millions) Unsecured Secured Total Unsecured Secured Total Long-term debt Due within one year $ 2,329 $ 9,048 $ 11,377 $ 4,274 $ 10,279 $ 14,553 Due after one year (a) 14,893 24,492 39,385 15,450 23,810 39,260 Fair value adjustment (b) 308 (9 ) 299 326 (11 ) 315 Total long-term debt (c) $ 17,530 $ 33,531 $ 51,061 $ 20,050 $ 34,078 $ 54,128 (a) Includes $2.6 billion of trust preferred securities at both March 31, 2017, and December 31, 2016. (b) Represents the fair value adjustment associated with the application of hedge accounting on certain of our long-term debt positions. Refer to Note 19 for additional information. (c) Includes advances from the FHLB of Pittsburgh of $6.1 billion at both March 31, 2017, and December 31, 2016. The following table presents the scheduled remaining maturity of long-term debt at March 31, 2017 , assuming no early redemptions will occur. The actual payment of secured debt may vary based on the payment activity of the related pledged assets. ($ in millions) 2017 2018 2019 2020 2021 2022 and thereafter Fair value adjustment Total Unsecured Long-term debt $ 1,811 $ 3,700 $ 1,681 $ 2,236 $ 638 $ 8,460 $ 308 $ 18,834 Original issue discount (69 ) (101 ) (39 ) (39 ) (42 ) (1,014 ) — (1,304 ) Total unsecured 1,742 3,599 1,642 2,197 596 7,446 308 17,530 Secured Long-term debt 7,575 8,534 8,080 5,175 2,558 1,618 (9 ) 33,531 Total long-term debt $ 9,317 $ 12,133 $ 9,722 $ 7,372 $ 3,154 $ 9,064 $ 299 $ 51,061 The following summarizes assets restricted as collateral for the payment of the related debt obligation primarily arising from securitization transactions accounted for as secured borrowings and repurchase agreements. March 31, 2017 December 31, 2016 ($ in millions) Total (a) Ally Bank Total (a) Ally Bank Investment securities (b) $ 3,175 $ 1,978 $ 4,895 $ 4,231 Mortgage assets held-for-investment and lending receivables 10,847 10,847 10,954 10,954 Consumer automotive finance receivables (b) 26,420 4,523 27,846 5,751 Commercial automotive finance receivables 17,901 17,709 19,487 19,280 Investment in operating leases, net 1,412 314 2,040 913 Total assets restricted as collateral (c) (d) $ 59,755 $ 35,371 $ 65,222 $ 41,129 Secured debt $ 37,001 (e) $ 15,120 $ 43,129 (e) $ 22,149 (a) Ally Bank is a component of the total column. (b) A portion of the restricted investment securities and consumer automotive finance receivables are restricted under repurchase agreements. Refer to the section above titled Short-term Borrowings for information on the repurchase agreements. (c) Ally Bank has an advance agreement with the FHLB, and had assets pledged to secure borrowings that were restricted as collateral to the FHLB totaling $16.8 billion and $19.0 billion at March 31, 2017 , and December 31, 2016 , respectively. These assets were composed primarily of consumer mortgage finance receivables and loans and investment securities. Ally Bank has access to the Federal Reserve Bank Discount Window. Ally Bank had assets pledged and restricted as collateral to the Federal Reserve Bank totaling $2.3 billion and $2.4 billion at March 31, 2017 , and December 31, 2016 , respectively. These assets were composed of consumer automotive finance receivables and loans and operating lease assets. Availability under these programs is only for the operations of Ally Bank and cannot be used to fund the operations or liabilities of Ally or its subsidiaries. (d) Excludes restricted cash and cash reserves for securitization trusts recorded within other assets on the Condensed Consolidated Balance Sheet . Refer to Note 12 for additional information. (e) Includes $3.5 billion and $9.1 billion of short-term borrowings at March 31, 2017 , and December 31, 2016 , respectively. Trust Preferred Securities At March 31, 2017 , we have issued and outstanding approximately $2.6 billion in aggregate liquidation preference of 8.125% Fixed Rate / Floating Rate Trust Preferred Securities, Series 2 (Series 2 TRUPS). Each Series 2 TRUPS security has a liquidation amount of $25. Distributions are cumulative and are payable until redemption at the applicable coupon rate. Distributions were payable at an annual rate of 8.125% payable quarterly in arrears, through but excluding February 15, 2016. From and including February 15, 2016, to but excluding February 15, 2040, distributions will be payable at an annual rate equal to three-month London interbank offer rate plus 5.785% payable quarterly in arrears, beginning May 15, 2016. Ally has the right to defer payments of interest for a period not exceeding 20 consecutive quarters. The Series 2 TRUPS have no stated maturity date, but must be redeemed upon the redemption or maturity of the related debentures (Debentures), which mature on February 15, 2040. Ally at any time on or after February 15, 2016, may redeem the Series 2 TRUPS at a redemption price equal to 100% of the principal amount being redeemed, plus accrued and unpaid interest through the date of redemption. The Series 2 TRUPS are generally nonvoting, other than with respect to certain limited matters. During any period in which any Series 2 TRUPS remain outstanding but in which distributions on the Series 2 TRUPS have not been fully paid, none of Ally or its subsidiaries will be permitted to (i) declare or pay dividends on, make any distributions with respect to, or redeem, purchase, acquire or otherwise make a liquidation payment with respect to, any of Ally’s capital stock or make any guarantee payment with respect thereto; or (ii) make any payments of principal, interest, or premium on, or repay, repurchase or redeem, any debt securities or guarantees that rank on a parity with or junior in interest to the Debentures with certain specified exceptions in each case. Funding Facilities We utilize both committed credit facilities and other collateralized funding vehicles. The debt outstanding under our various funding facilities is included on our Condensed Consolidated Balance Sheet . As of March 31, 2017 , Ally Bank had exclusive access to $2.4 billion of funding capacity from committed credit facilities. Funding programs supported by the Federal Reserve and the FHLB, together with repurchase agreements, complement Ally Bank’s private collateralized funding vehicles. The total capacity in our committed funding facilities is provided by banks through private transactions. The committed secured funding facilities can be revolving in nature and allow for additional funding during the commitment period, or they can be amortizing and not allow for any further funding after the closing date. At March 31, 2017 , $15.6 billion of our $16.4 billion of committed capacity was revolving. Our revolving facilities generally have an original tenor ranging from 364 days to two years. As of March 31, 2017 , we had $3.1 billion of committed funding capacity from revolving facilities with a remaining tenor greater than 364 days. Committed Funding Facilities Outstanding Unused capacity (a) Total capacity ($ in millions) March 31, 2017 December 31, 2016 March 31, 2017 December 31, 2016 March 31, 2017 December 31, 2016 Bank funding Secured (b) $ 2,050 $ 3,250 $ 350 $ 350 $ 2,400 $ 3,600 Parent funding Secured 12,123 11,550 652 1,975 12,775 13,525 Unsecured 1,250 — — 1,250 1,250 1,250 Total committed facilities $ 15,423 $ 14,800 $ 1,002 $ 3,575 $ 16,425 $ 18,375 (a) Funding from committed secured facilities is available on request in the event excess collateral resides in certain facilities or is available to the extent incremental collateral is available and contributed to the facilities. (b) Excludes off-balance sheet credit facility amounts.

Accrued Expenses and Other Liab

Accrued Expenses and Other Liabilities	3 Months Ended
	Mar. 31, 2017
Accounts Payable and Accrued Liabilities [Abstract]
Accounts Payable and Accrued Liabilities Disclosure [Text Block]	Accrued Expenses and Other Liabilities The components of accrued expenses and other liabilities were as follows. ( $ in millions ) March 31, 2017 December 31, 2016 Accounts payable $ 851 $ 649 Reserves for insurance losses and loss adjustment expenses 175 149 Employee compensation and benefits 156 232 Fair value of derivative contracts in payable position (a) 81 95 Deferred revenue 47 56 Cash collateral received from counterparties 12 10 Other liabilities 600 546 Total accrued expenses and other liabilities $ 1,922 $ 1,737 (a) For additional information on derivative instruments and hedging activities, refer to Note 19 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	3 Months Ended
	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Abstract]
Comprehensive Income (Loss) Note [Text Block]	Accumulated Other Comprehensive Loss The following table presents changes, net of tax, in each component of accumulated other comprehensive loss. ($ in millions) Unrealized (losses) gains on investment securities (a) Translation adjustments and net investment hedges (b) Cash flow hedges (b) Defined benefit pension plans Accumulated other comprehensive loss Balance at December 31, 2015 $ (159 ) $ 9 $ 8 $ (89 ) $ (231 ) 2016 net change 142 5 — (1 ) 146 Balance at March 31, 2016 $ (17 ) $ 14 $ 8 $ (90 ) $ (85 ) Balance at December 31, 2016 $ (273 ) $ 14 $ 8 $ (90 ) $ (341 ) 2017 net change 21 — — (1 ) 20 Balance at March 31, 2017 $ (252 ) $ 14 $ 8 $ (91 ) $ (321 ) (a) Represents the after-tax difference between the fair value and amortized cost of our available-for-sale securities portfolio. (b) For additional information on derivative instruments and hedging activities, refer to Note 19 . The following tables present the before- and after-tax changes in each component of accumulated other comprehensive loss. Three months ended March 31, 2017 ($ in millions) Before tax Tax effect After tax Investment securities Net unrealized gains arising during the period $ 51 $ (5 ) $ 46 Less: Net realized gains reclassified to income from continuing operations 27 (a) (2 ) (b) 25 Net change 24 (3 ) 21 Translation adjustments Net unrealized gains arising during the period 2 (1 ) 1 Net investment hedges (c) Net unrealized losses arising during the period (2 ) 1 (1 ) Defined benefit pension plans Net unrealized losses arising during the period (1 ) — (1 ) Other comprehensive income $ 23 $ (3 ) $ 20 (a) Includes gains reclassified to other gain on investments, net in our Condensed Consolidated Statement of Comprehensive Income . (b) Includes amounts reclassified to income tax expense from continuing operations in our Condensed Consolidated Statement of Comprehensive Income . (c) For additional information on derivative instruments and hedging activities, refer to Note 19 . Three months ended March 31, 2016 ($ in millions) Before tax Tax effect After tax Investment securities Net unrealized gains arising during the period $ 280 $ (104 ) $ 176 Less: Net realized gains reclassified to income from continuing operations 54 (a) (20 ) (b) 34 Net change 226 (84 ) 142 Translation adjustments Net unrealized gains arising during the period 13 (5 ) 8 Net investment hedges (c) Net unrealized losses arising during the period (6 ) 3 (3 ) Defined benefit pension plans Net unrealized losses arising during the period (1 ) — (1 ) Other comprehensive income $ 232 $ (86 ) $ 146 (a) Includes gains reclassified to other gain on investments, net in our Condensed Consolidated Statement of Comprehensive Income . (b) Includes amounts reclassified to income tax expense from continuing operations in our Condensed Consolidated Statement of Comprehensive Income . (c) For additional information on derivative instruments and hedging activities, refer to Note 19 .

Earnings per Common Share

Earnings per Common Share	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	Earnings per Common Share The following table presents the calculation of basic and diluted earnings per common share. Three months ended March 31, ( $ in millions, except per share data; shares in thousands ) (a) 2017 2016 Net income from continuing operations $ 213 $ 247 Preferred stock dividends — (15 ) Net income from continuing operations attributable to common shareholders 213 232 Income from discontinued operations, net of tax 1 3 Net income attributable to common shareholders $ 214 $ 235 Basic weighted-average common shares outstanding (b) 465,961 484,233 Diluted weighted-average common shares outstanding (b) 466,829 484,654 Basic earnings per common share Net income from continuing operations $ 0.46 $ 0.48 Income from discontinued operations, net of tax — 0.01 Net income $ 0.46 $ 0.49 Diluted earnings per common share Net income from continuing operations $ 0.46 $ 0.48 Income from discontinued operations, net of tax — 0.01 Net income $ 0.46 $ 0.49 (a) Figures in the table may not recalculate exactly due to rounding. Earnings per share is calculated based on unrounded numbers. (b) Includes shares related to share-based compensation that vested but were not yet issued for the three months ended March 31, 2017 , and 2016 , respectively.

Regulatory Capital and Other Re

Regulatory Capital and Other Regulatory Matters	3 Months Ended
	Mar. 31, 2017
Regulatory Capital Requirements [Abstract]
Regulatory Capital Requirements under Banking Regulations [Text Block]	Regulatory Capital and Other Regulatory Matters As a BHC, we and our wholly-owned state-chartered banking subsidiary, Ally Bank, are subject to capital requirements issued by U.S. banking regulators that require us to maintain risk-based and leverage capital ratios above minimum levels. A risk-based capital ratio is a ratio of a banking organization’s regulatory capital to its risk-weighted assets. A leverage capital ratio is a ratio of a banking organization’s regulatory capital to a measure of assets or exposures that is not risk-weighted. As of January 1, 2015, Ally and Ally Bank became subject to the rules implementing the 2010 Basel III capital framework in the United States (U.S. Basel III), which generally reflects higher capital requirements, capital buffers, and changes to regulatory capital definitions, deductions and adjustments, relative to the predecessor requirements implementing the Basel I capital framework in the United States. Certain aspects of U.S. Basel III, including the capital buffers and certain regulatory capital deductions, will be phased in over several years. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary action by regulators that, if undertaken, could have a direct material effect on the Condensed Consolidated Financial Statements or the results of operations and financial condition of Ally and Ally Bank. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, we and Ally Bank must meet specific capital guidelines that involve quantitative measures of capital, assets and certain off-balance sheet items. These measures and related classifications, which are used in the calculation of our risk-based and leverage capital ratios and those of Ally Bank, are also subject to qualitative judgments by the regulators about the components of capital, the risk-weightings of assets and other exposures, and other factors. The FRB also uses these ratios and guidelines as part of the capital planning and stress testing processes. In addition, in order for Ally to maintain its status as a FHC, Ally and its bank subsidiary, Ally Bank, must remain “well-capitalized” and “well-managed,” as defined under applicable laws. The “well-capitalized” standard for insured depository institutions, such as Ally Bank, reflects the capital requirements under U.S. Basel III. Under U.S. Basel III, Ally must maintain a minimum Common Equity Tier 1 risk-based capital ratio of 4.5% , a minimum Tier 1 risk-based capital ratio of 6% , and a minimum Total risk-based capital ratio of 8% . In addition to these minimum requirements, Ally is also subject to a Common Equity Tier 1 capital conservation buffer of more than 2.5% , subject to a phase-in period from January 1, 2016, through December 31, 2018. Failure to maintain the full amount of the buffer will result in restrictions on Ally’s ability to make capital distributions, including dividend payment and stock repurchases and redemptions, and to pay discretionary bonuses to executive officers. In addition to these new risk-based capital standards, U.S. Basel III subjects all U.S. banking organizations, including Ally, to a minimum Tier 1 leverage ratio of 4% , the denominator of which takes into account only on-balance sheet assets. U.S. Basel III also revised the eligibility criteria for regulatory capital instruments and provides for the phase-out of instruments that had previously been recognized as capital but that do not satisfy these criteria. Subject to certain exceptions (e.g., for certain debt or equity issued to the U.S. government under the Emergency Economic Stabilization Act), trust preferred and other “hybrid” securities are no longer included in a BHC's Tier 1 capital as of January 1, 2016. Also, subject to a phase-in schedule, certain items are deducted from Common Equity Tier 1 capital that had not previously been deducted from regulatory capital, and certain other deductions from regulatory capital have been modified. Among other things, U.S. Basel III requires significant investments in the common shares of unconsolidated financial institutions, mortgage servicing rights, and certain deferred tax assets that exceed specified individual and aggregate thresholds to be deducted from Common Equity Tier 1 capital. U.S. Basel III also revised the standardized approach for calculating risk-weighted assets by, among other things, modifying certain risk weights and the methods for calculating risk-weighted assets for certain types of assets and exposures. Ally is subject to the U.S. Basel III standardized approach for credit risk. It is not subject to the U.S. Basel III advanced approaches for credit risk. Ally is currently not subject to the U.S. market risk capital rule, which applies only to banking organizations with significant trading assets and liabilities. On March 7, 2016, Ally Bank received approval from the Federal Reserve to become a state member bank. Ally Bank is now regulated by the FRB through the Federal Reserve Bank of Chicago, as well as the Utah Department of Financial Institutions (UDFI). In addition, in connection with the application for membership in the Federal Reserve System, Ally Bank made commitments to the FRB relating to capital, liquidity, and business plan requirements. These commitments are consistent with the prior requirements under the now-terminated Capital and Liquidity Maintenance Agreement with the Federal Deposit Insurance Corporation (FDIC), including the requirement to maintain capital at a level such that Ally Bank’s Tier 1 leverage ratio is at least 15% . For this purpose, the Tier 1 leverage ratio is determined in accordance with the FRB's regulations related to capital adequacy. As a requirement of Federal Reserve membership, we held $435 million of FRB stock at March 31, 2017 . Compliance with capital requirements is a strategic priority for Ally. We expect to be in compliance with all applicable requirements within the established timeframes. The following table summarizes our capital ratios under the U.S. Basel III capital framework. March 31, 2017 December 31, 2016 Required Well-capitalized ( $ in millions ) Amount Ratio Amount Ratio Capital ratios Common Equity Tier 1 (to risk-weighted assets) Ally Financial Inc. $ 12,923 9.40 % $ 12,978 9.37 % 4.50 % (a) Ally Bank 18,562 17.74 17,888 16.70 4.50 6.50 % Tier 1 (to risk-weighted assets) Ally Financial Inc. $ 15,245 11.09 % $ 15,147 10.93 % 6.00 % 6.00 % Ally Bank 18,562 17.74 17,888 16.70 6.00 8.00 Total (to risk-weighted assets) Ally Financial Inc. $ 17,459 12.70 % $ 17,419 12.57 % 8.00 % 10.00 % Ally Bank 19,167 18.32 18,458 17.24 8.00 10.00 Tier 1 leverage (to adjusted quarterly average assets) (b) Ally Financial Inc. $ 15,245 9.51 % $ 15,147 9.54 % 4.00 % (a) Ally Bank 18,562 15.38 17,888 15.21 15.00 (c) 5.00 % (a) Currently, there is no ratio component for determining whether a BHC is "well-capitalized." (b) Federal regulatory reporting guidelines require the calculation of adjusted quarterly average assets using a daily average methodology. (c) Ally Bank has committed to the FRB to maintain a Tier 1 leverage ratio of at least 15% . At March 31, 2017 , Ally and Ally Bank were “well-capitalized” and met all capital requirements to which each was subject. Capital Planning and Stress Tests As a BHC with $50 billion or more of consolidated assets, Ally is required to conduct semi-annual company-run stress tests, is subject to an annual supervisory stress test conducted by the FRB, and must submit an annual capital plan to the FRB. Ally’s capital plan must include a description of all planned capital actions over a nine-quarter planning horizon. The capital plan must also include a discussion of how Ally will maintain capital above the minimum regulatory capital ratios under baseline, adverse, and severely adverse economic scenarios, and serve as a source of strength to Ally Bank. The FRB must approve Ally's capital plan before Ally may take any capital action. Even with an approved capital plan, Ally must seek the approval of the FRB before making a capital distribution if, among other factors, Ally would not meet its regulatory capital requirements after making the proposed capital distribution. As part of the 2016 Comprehensive Capital Analysis and Review (CCAR) process, we received approval for capital actions including a quarterly cash dividend of $0.08 per share of our common stock, subject to quarterly approval by the Board of Directors, and the ability to repurchase up to $700 million of our common stock from time to time through the second quarter of 2017. Our first common stock dividend was paid during the third quarter of 2016 and we paid a cash dividend of $0.08 per share on our common stock during each subsequent quarter. On April 14, 2017 , the Ally Board of Directors declared a quarterly cash dividend payment of $0.08 per share on all common stock. Refer to Note 26 for further information regarding this common share dividend. Additionally, the Ally Board of Directors authorized a common stock repurchase program of up to $700 million beginning in the third quarter of 2016 and continuing through the second quarter of 2017. Under this program, we have repurchased $495 million , or 25,140,190 shares of common stock, which reduced total shares by approximately 5.2% since inception. At March 31, 2017 , we had 462,193,424 shares of common stock outstanding. Ally submitted its 2017 capital plan on April 5, 2017, with capital actions including distributions to common shareholders through share repurchases and cash dividends. Our ability to make capital distributions, including our ability to pay dividends or repurchase shares of our common stock, will continue to be subject to the FRB’s review of and non-objection to the actions that we propose each year in our annual capital plan. We expect to receive the FRB’s response (either a non-objection or objection) to the capital plan submitted by June 30, 2017. In January 2017, the FRB finalized a rule amending the capital planning and stress testing rules, effective for the 2017 cycle. The final rule, among other things, revised the capital plan rule to no longer subject large and noncomplex firms, including Ally, to the provisions of the rule whereby the FRB may object to a capital plan on the basis of qualitative deficiencies in the firm’s capital planning process. Under the final rule, the qualitative assessment of Ally’s capital plan is conducted outside of the CCAR process, through the supervisory review process, and Ally’s reporting requirements have been modified to reduce certain reporting burdens related to capital planning and stress testing. The final rule also decreased the de minimis threshold for the amount of capital that Ally could distribute to shareholders outside of an approved capital plan without seeking prior approval of the FRB.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	3 Months Ended
	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	Derivative Instruments and Hedging Activities We enter into interest rate, foreign-currency, and equity swaps, futures, forwards, options, and swaptions in connection with our market risk management activities. Derivative instruments are used to manage interest rate risk relating to specific groups of assets and liabilities, including automotive loan assets and debt. We use foreign exchange contracts to mitigate foreign-currency risk associated with foreign-currency-denominated debt, foreign exchange transactions, and our net investment in foreign subsidiaries. In addition, we also enter into equity option contracts to manage our exposure to the equity markets. Our primary objective for utilizing derivative financial instruments is to manage interest rate risk associated with our fixed- and variable-rate assets and liabilities, foreign exchange risks related to our foreign-currency denominated assets and liabilities, and market risks related to our investment portfolio and certain of our executive share-based compensation plans. Interest Rate Risk We monitor our mix of fixed- and variable-rate assets and liabilities. We may enter into interest rate swaps, forwards, futures, options, and swaptions to achieve our desired mix of fixed- and variable-rate assets and liabilities. We execute interest rate swaps, forwards, futures, options, and swaptions to modify our exposure to interest rate risk by converting certain fixed-rate instruments to a variable-rate and certain variable-rate instruments to a fixed-rate. We use a mix of both derivatives that qualify for hedge accounting treatment and economic hedges. Derivatives qualifying for hedge accounting consist of receive-fixed swaps designated as fair value hedges of specific fixed-rate unsecured debt obligations, receive-fixed swaps designated as fair value hedges of specific fixed-rate FHLB advances and pay-fixed swaps designated as fair value hedges of specific portfolios of fixed-rate held-for-investment retail automotive loan assets. We also execute economic hedges, which consist of interest rate swaps and interest rate caps held to mitigate interest rate risk associated with our debt portfolio. We also use interest rate swaps to economically hedge our net fixed-versus-variable interest rate exposure. We enter into economic hedges in the form of short-dated, exchange-traded Eurodollar futures to hedge the interest rate exposure of our fixed-rate automotive loans, as well as forwards, options, and swaptions to economically hedge our net fixed-versus-variable interest rate exposure. Foreign Exchange Risk We enter into derivative financial instrument contracts to mitigate the risk associated with variability in cash flows related to our various foreign-currency exposures. We enter into foreign-currency forwards with external counterparties as net investment hedges of foreign exchange exposure on our investments in foreign subsidiaries. Our equity is impacted by the cumulative translation adjustments resulting from the translation of foreign subsidiary results; this impact is reflected in our accumulated other comprehensive loss. We also periodically enter into foreign-currency forwards to economically hedge our foreign-denominated debt, our centralized lending program, and foreign-denominated third-party loans. These forward currency forwards that are used as economic hedges are recorded at fair value with changes recorded as income offsetting the gains and losses on the associated foreign-currency transactions. Market Risk We enter into equity options to economically hedge our exposure to the equity markets. We purchase options to assume a long position on certain equities and write options to assume a short position. Counterparty Credit Risk Derivative financial instruments contain an element of credit risk if counterparties are unable to meet the terms of the agreements. Credit risk associated with derivative financial instruments is measured as the net replacement cost should the counterparties that owe us under the contract completely fail to perform under the terms of those contracts, assuming no recoveries of underlying collateral as measured by the market value of the derivative financial instrument. To mitigate the risk of counterparty default, we maintain collateral agreements with certain counterparties. The agreements generally require both parties to post collateral in the event the fair values of the derivative financial instruments meet posting thresholds established under the agreements. In the event that either party defaults on the obligation, the secured party may seize the collateral. Generally, our collateral arrangements are bilateral such that we and the counterparty post collateral for the value of our total obligation to each other. Contractual terms provide for standard and customary exchange of collateral based on changes in the market value of the outstanding derivatives. The securing party posts additional collateral when their obligation rises or removes collateral when it falls. Certain derivative instruments contain provisions that require us to either post additional collateral or immediately settle any outstanding liability balances upon the occurrence of a specified credit risk-related event. No such specified credit risk related events occurred during the first quarter of 2017 or 2016. We placed cash collateral totaling $115 million and securities collateral totaling $59 million at March 31, 2017 , and $122 million and $72 million at December 31, 2016 , respectively, in accounts maintained by counterparties. This amount primarily relates to collateral posted to support our derivative positions. This amount also excludes cash and securities pledged as collateral under repurchase agreements. At March 31, 2017 , and December 31, 2016 , we placed cash collateral totaling $5 million and $45 million , respectively, with counterparties under collateral arrangements associated with repurchase agreements. Refer to Note 14 for details on the repurchase agreements. The receivables for cash collateral placed are included in our Condensed Consolidated Balance Sheet in other assets. We received cash collateral from counterparties totaling $12 million and $10 million at March 31, 2017, and December 31, 2016, respectively, primarily to support these derivative positions. This amount also excludes cash and securities pledged as collateral under repurchase agreements. At March 31, 2017, we received cash collateral totaling $1 million from counterparties under collateral arrangements associated with repurchase agreements. Refer to Note 14 for details on the repurchase agreements. The payables for cash collateral received are included on our Condensed Consolidated Balance Sheet in accrued expenses and other liabilities. In certain circumstances, we receive or post securities as collateral with counterparties. We do not record collateral received on our Condensed Consolidated Balance Sheet unless certain conditions are met. At March 31, 2017 , and December 31, 2016 , we received noncash collateral of $6 million . Included in these amounts is noncash collateral where we have been granted the right to sell or pledge the underlying assets. We have not sold or pledged any of the noncash collateral received under these agreements. Balance Sheet Presentation The following table summarizes the fair value amounts of derivative instruments reported on our Condensed Consolidated Balance Sheet . The fair value amounts are presented on a gross basis, are segregated by derivatives that are designated and qualifying as hedging instruments or those that are not, and are further segregated by type of contract within those two categories. Notional amounts are reference amounts from which contractual obligations are derived and are not recorded on the balance sheet. In our view, derivative notional is not an accurate measure of our derivative exposure when viewed in isolation from other factors, such as market rate fluctuations and counterparty credit risk. March 31, 2017 December 31, 2016 Derivative contracts in a Notional Derivative contracts in a Notional ($ in millions) receivable payable receivable payable Derivatives designated as accounting hedges Interest rate contracts Swaps (c) (d) (e) $ 18 $ 17 $ 3,939 $ 19 $ 21 $ 4,731 Foreign exchange contracts Forwards — 1 150 1 — 171 Total derivatives designated as accounting hedges 18 18 4,089 20 21 4,902 Derivatives not designated as accounting hedges Interest rate contracts Swaps — — 43 — — 137 Futures and forwards — — 25 — — — Written options — 62 13,432 — 73 14,518 Purchased options 62 — 13,407 73 — 14,517 Total interest rate risk 62 62 26,907 73 73 29,172 Foreign exchange contracts Futures and forwards — 1 94 1 — 92 Total foreign exchange risk — 1 94 1 — 92 Equity contracts Written options — — — — 1 — Purchased options — — — 1 — — Total equity risk — — — 1 1 — Total derivatives not designated as accounting hedges 62 63 27,001 75 74 29,264 Total derivatives $ 80 $ 81 $ 31,090 $ 95 $ 95 $ 34,166 (a) Derivative contracts in a receivable position are classified as other assets on the Condensed Consolidated Balance Sheet , and include accrued interest of $3 million and $7 million at March 31, 2017 , and December 31, 2016 , respectively. (b) Derivative contracts in a liability position are classified as accrued expenses and other liabilities on the Condensed Consolidated Balance Sheet , and include accrued interest of $0 million and $1 million at March 31, 2017 , and December 31, 2016 , respectively. (c) Includes fair value hedges consisting of receive-fixed swaps on fixed-rate unsecured debt obligations with $11 million and $8 million in a receivable position, $18 million and $14 million in a payable position, and a $2.6 billion and $1.7 billion notional amount at March 31, 2017 , and December 31, 2016 , respectively. The hedge notional amount of $2.6 billion at March 31, 2017 , is associated with debt maturing in approximately five or more years. (d) Includes fair value hedges consisting of receive-fixed swaps on fixed-rate secured debt obligations (FHLB advances) with $0 million and $0 million in a receivable position, $0 million and $7 million in a payable position, and a $0 million and $240 million notional amount at March 31, 2017 , and December 31, 2016 , respectively. (e) Other fair value hedges include pay-fixed swaps on portfolios of held-for-investment automotive loan assets with $7 million and $10 million in a receivable position, $0 million and $1 million in a payable position, and a $1.4 billion and $2.8 billion notional amount at March 31, 2017 , and December 31, 2016 , respectively. Statement of Comprehensive Income Presentation The following table summarizes the location and amounts of gains and losses on derivative instruments reported in our Condensed Consolidated Statement of Comprehensive Income . Three months ended March 31, ( $ in millions ) 2017 2016 Derivatives qualifying for hedge accounting Gain (loss) recognized in earnings on derivatives Interest rate contracts Interest and fees on finance receivables and loans (a) $ 2 $ (28 ) Interest on long-term debt (b) (c) 4 191 (Loss) gain recognized in earnings on hedged items Interest rate contracts Interest and fees on finance receivables and loans (d) (4 ) 28 Interest on long-term debt (e) (f) (3 ) (196 ) Total derivatives qualifying for hedge accounting (1 ) (5 ) Derivatives not designated as accounting hedges (Loss) gain recognized in earnings on derivatives Interest rate contracts Other income, net of losses (2 ) 2 Total interest rate contracts (2 ) 2 Foreign exchange contracts (g) Interest on long-term debt — (1 ) Other income, net of losses (1 ) (4 ) Total foreign exchange contracts (1 ) (5 ) Equity contracts Compensation and benefits expense — (1 ) Total equity contracts — (1 ) Loss recognized in earnings on derivatives $ (4 ) $ (9 ) (a) Amounts exclude losses related to interest for qualifying accounting hedges of retail automotive loans held-for-investment, which are primarily offset by the fixed coupon payments of the loans. The losses were $1 million and $7 million for the three months ended March 31, 2017 , and 2016 , respectively. (b) Amounts exclude gains related to interest for qualifying accounting hedges of unsecured debt, which are primarily offset by the fixed coupon payment on the long-term debt. The gains were $5 million and $16 million for the three months ended March 31, 2017 , and 2016 , respectively. (c) Amounts exclude gains related to interest for qualifying accounting hedges of secured debt (FHLB advances), which are primarily offset by the fixed coupon payment on the long-term debt. The gains were $0 million and $1 million for the three months ended March 31, 2017 , and 2016 , respectively. (d) Amounts exclude losses related to amortization of deferred loan basis adjustments on the de-designated hedged item of $5 million for both the three months ended March 31, 2017 , and 2016 . (e) Amounts exclude gains related to amortization of deferred debt basis adjustments on the de-designated hedged item of $20 million and $18 million for the three months ended March 31, 2017 , and 2016 , respectively. (f) Amounts exclude losses related to amortization of deferred debt basis adjustments (FHLB advances) on the de-designated hedge item of $1 million and $0 million for the three months ended March 31, 2017, and 2016, respectively. (g) Amounts exclude gains and losses related to the revaluation of the related foreign-denominated debt or receivable. Gains of $1 million and $4 million were recognized for the three months ended March 31, 2017 , and 2016 , respectively. Losses of $2 million and $6 million were recognized in other comprehensive income for the three months ended March 31, 2017, and 2016, respectively. These amounts represent the effective portion of net investment hedges. There are offsetting amounts recognized in accumulated other comprehensive loss related to the revaluation of the related net investment in foreign operations, including the tax impacts of the hedge and related net investment, as disclosed separately in Note 16 . There were gains of $3 million and $11 million for the three months ended March 31, 2017 , and 2016, respectively.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	Income Taxes We recognized total income tax expense from continuing operations of $113 million for the three months ended March 31, 2017 , compared to income tax expense of $150 million for the same period in 2016 . The decrease in income tax expense for the three months ended March 31, 2017 , compared to the same period in 2016 , was primarily driven by a decrease in pretax earnings and a tax benefit for the current quarter related to stock compensation and associated movements in our share price. As of each reporting date, we consider existing evidence, both positive and negative, that could impact our view with regard to future realization of deferred tax assets. We continue to believe it is more likely than not that the benefit for capital loss carryforwards, certain foreign tax credits, and state net operating loss carryforwards will not be realized. In recognition of this risk, we continue to provide a full valuation allowance on capital loss carryforwards and a partial valuation allowance on the deferred tax assets relating to foreign tax credits and state net operating loss carryforwards.

Fair Value

Fair Value	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Text Block]	Fair Value Fair Value Measurements For purposes of this disclosure, fair value is defined as the exchange price that would be received to sell an asset or paid to transfer a liability (exit price) in the principal or most advantageous market in an orderly transaction between market participants at the measurement date under current market conditions. Fair value is based on the assumptions we believe market participants would use when pricing an asset or liability. Additionally, entities are required to consider all aspects of nonperformance risk, including the entity’s own credit standing, when measuring the fair value of a liability. GAAP specifies a three-level hierarchy that is used when measuring and disclosing fair value. The fair value hierarchy gives the highest priority to quoted prices available in active markets (i.e., observable inputs) and the lowest priority to data lacking transparency (i.e., unobservable inputs). An instrument’s categorization within the fair value hierarchy is based on the lowest level of significant input to its valuation. The following is a description of the three hierarchy levels. Level 1 Inputs are quoted prices in active markets for identical assets or liabilities at the measurement date. Additionally, the entity must have the ability to access the active market, and the quoted prices cannot be adjusted by the entity. Level 2 Inputs are other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices in active markets for similar assets or liabilities; quoted prices in inactive markets for identical or similar assets or liabilities; or inputs that are observable or can be corroborated by observable market data by correlation or other means for substantially the full term of the assets or liabilities. Level 3 Unobservable inputs are supported by little or no market activity. The unobservable inputs represent management's best assumptions of how market participants would price the assets or liabilities. Generally, Level 3 assets and liabilities are valued using pricing models, discounted cash flow methodologies, or similar techniques that require significant judgment or estimation. Transfers Transfers into or out of any hierarchy level are recognized at the end of the reporting period in which the transfer occurred. There were no transfers between any levels for the three months ended March 31, 2017 . Following are descriptions of the valuation methodologies used to measure material assets and liabilities at fair value and details of the valuation models, key inputs to those models, and significant assumptions utilized. • Available-for-sale securities — All classes of available-for-sale securities are carried at fair value based on observable market prices, when available. If observable market prices are not available, our valuations are based on internally developed discounted cash flow models (an income approach) that use a market-based discount rate and consider recent market transactions, experience with similar securities, current business conditions, and analysis of the underlying collateral, as available. To estimate cash flows, we are required to utilize various significant assumptions including market observable inputs (e.g., forward interest rates) and internally developed inputs (including prepayment speeds, delinquency levels, and credit losses). • Interests retained in financial asset sales — Includes certain noncertificated interests retained from the sale of automotive finance receivables. Due to inactivity in the market, valuations are based on internally developed discounted cash flow models (an income approach) that use a market-based discount rate; therefore, we classified these assets as Level 3. The valuation considers recent market transactions, experience with similar assets, current business conditions, and analysis of the underlying collateral, as available. To estimate cash flows, we utilize various significant assumptions, including market observable inputs (e.g., forward interest rates) and internally developed inputs (e.g., prepayment speeds, delinquency levels, and credit losses). • Derivative instruments — We enter into a variety of derivative financial instruments as part of our risk management strategies. Certain of these derivatives are exchange traded, such as Eurodollar futures, options of Eurodollar futures, and equity options. To determine the fair value of these instruments, we utilize the quoted market prices for the particular derivative contracts; therefore, we classified these contracts as Level 1. We also execute over-the-counter (OTC) and centrally-cleared derivative contracts, such as interest rate swaps, a cross-currency swap, swaptions, foreign-currency denominated forward contracts, prepaid equity forward contracts, caps, floors, and agency to-be-announced securities. For OTC contracts, we utilize third-party-developed valuation models that are widely accepted in the market to value these OTC derivative contracts. The specific terms of the contract and market observable inputs (such as interest rate forward curves, interpolated volatility assumptions, or equity pricing) are used in the model. We classified these OTC derivative contracts as Level 2 because all significant inputs into these models were market observable. For centrally-cleared contracts, we utilize unadjusted prices obtained from the clearing house as the basis for valuation, and they are also classified as Level 2. We did not have any derivative instruments classified as Level 3 as of March 31, 2017 , or December 31, 2016 . We are required to consider all aspects of nonperformance risk, including our own credit standing, when measuring fair value of a liability. We reduce credit risk on the majority of our derivatives by entering into legally enforceable agreements that enable the posting and receiving of collateral associated with the fair value of our derivative positions on an ongoing basis. In the event that we do not enter into legally enforceable agreements that enable the posting and receiving of collateral, we will consider our credit risk and the credit risk of our counterparties in the valuation of derivative instruments through a credit valuation adjustment (CVA), if warranted. The CVA calculation utilizes the credit default swap spreads of the counterparty. Recurring Fair Value The following tables display the assets and liabilities measured at fair value on a recurring basis including financial instruments elected for the fair value option. We often economically hedge the fair value change of our assets or liabilities with derivatives and other financial instruments. The tables below display the hedges separately from the hedged items; therefore, they do not directly display the impact of our risk management activities. Recurring fair value measurements March 31, 2017 ($ in millions) Level 1 Level 2 Level 3 Total Assets Investment securities Available-for-sale securities Debt securities U.S. Treasury $ 2,225 $ — $ — $ 2,225 U.S. States and political subdivisions — 795 — 795 Foreign government 9 137 — 146 Agency mortgage-backed residential — 11,862 — 11,862 Mortgage-backed residential — 1,996 — 1,996 Mortgage-backed commercial — 534 — 534 Asset-backed — 1,051 — 1,051 Corporate debt — 1,255 — 1,255 Total debt securities 2,234 17,630 — 19,864 Equity securities (a) 444 — — 444 Total available-for-sale securities 2,678 17,630 — 20,308 Mortgage loans held-for-sale — — 1 1 Interests retained in financial asset sales — — 31 31 Derivative contracts in a receivable position (b) Interest rate — 80 — 80 Total derivative contracts in a receivable position — 80 — 80 Total assets $ 2,678 $ 17,710 $ 32 $ 20,420 Liabilities Accrued expenses and other liabilities Derivative contracts in a payable position (b) Interest rate $ — $ (80 ) $ — $ (80 ) Foreign currency — (1 ) — (1 ) Total derivative contracts in a payable position — (81 ) — (81 ) Total liabilities $ — $ (81 ) $ — $ (81 ) (a) Our investment in any one industry did not exceed 16% . (b) For additional information on derivative instruments and hedging activities, refer to Note 19 . Recurring fair value measurements December 31, 2016 ($ in millions) Level 1 Level 2 Level 3 Total Assets Investment securities Available-for-sale securities Debt securities U.S. Treasury $ 1,620 $ — $ — $ 1,620 U.S. States and political subdivisions — 782 — 782 Foreign government 11 151 — 162 Agency mortgage-backed residential — 10,290 — 10,290 Mortgage-backed residential — 2,097 — 2,097 Mortgage-backed commercial — 537 — 537 Asset-backed — 1,400 — 1,400 Corporate debt — 1,443 — 1,443 Total debt securities 1,631 16,700 — 18,331 Equity securities (a) 595 — — 595 Total available-for-sale securities 2,226 16,700 — 18,926 Other assets Interests retained in financial asset sales — — 29 29 Derivative contracts in a receivable position (b) Interest rate — 92 — 92 Foreign currency — 2 — 2 Other 1 — — 1 Total derivative contracts in a receivable position 1 94 — 95 Total assets $ 2,227 $ 16,794 $ 29 $ 19,050 Liabilities Accrued expenses and other liabilities Derivative contracts in a payable position (b) Interest rate $ — $ (94 ) $ — $ (94 ) Other (1 ) — — (1 ) Total derivative contracts in a payable position (1 ) (94 ) — (95 ) Total liabilities $ (1 ) $ (94 ) $ — $ (95 ) (a) Our investment in any one industry did not exceed 14% . (b) For additional information on derivative instruments and hedging activities, refer to Note 19 . The following tables present the reconciliation for all Level 3 assets and liabilities measured at fair value on a recurring basis. We often economically hedge the fair value change of our assets or liabilities with derivatives and other financial instruments. The Level 3 items presented below may be hedged by derivatives and other financial instruments that are classified as Level 1 or Level 2. Thus, the following tables do not fully reflect the impact of our risk management activities. Level 3 recurring fair value measurements Net realized/unrealized Fair value at Net unrealized gains included in earnings ($ in millions) Fair value at Jan. 1, 2017 included in earnings included in OCI Purchases Sales Issuances Settlements Assets Mortgage loans held-for-sale $ — $ — $ — $ 3 $ (2 ) $ — $ — $ 1 $ — Other assets Interests retained in financial asset sales 29 — — — 4 — (2 ) 31 — Total assets $ 29 $ — $ — $ 3 $ 2 $ — $ (2 ) $ 32 $ — Level 3 recurring fair value measurements Fair value at Jan. 1, 2016 Net realized/unrealized Purchases Sales Issuances Settlements Fair value at Net unrealized gains included in earnings ($ in millions) included in earnings included in OCI Assets Other assets Interests retained in financial asset sales $ 40 $ 2 (a) $ — $ — $ 4 $ — $ (15 ) $ 31 $ — Total assets $ 40 $ 2 $ — $ — $ 4 $ — $ (15 ) $ 31 $ — (a) Reported as other income, net of losses, in the Condensed Consolidated Statement of Comprehensive Income . Nonrecurring Fair Value We may be required to measure certain assets and liabilities at fair value from time to time. These periodic fair value measures typically result from the application of lower-of-cost or fair value accounting or certain impairment measures. These items would constitute nonrecurring fair value measures. The following tables display the assets and liabilities measured at fair value on a nonrecurring basis. Nonrecurring Lower-of-cost or Total gain (loss) included in earnings for the three months ended March 31, 2017 ($ in millions) Level 1 Level 2 Level 3 Total Assets Commercial finance receivables and loans, net (a) Commercial and industrial Automotive $ — $ — $ 29 $ 29 $ (3 ) n/m (b) Other — — 61 61 (21 ) n/m (b) Total commercial finance receivables and loans, net — — 90 90 (24 ) n/m (b) Other assets Repossessed and foreclosed assets (c) — — 15 15 (2 ) n/m (b) Other — — 4 4 — n/m (b) Total assets $ — $ — $ 109 $ 109 $ (26 ) n/m n/m = not meaningful (a) Represents the portion of the portfolio specifically impaired during 2017 . The related valuation allowance represents the cumulative adjustment to fair value of those specific receivables. (b) We consider the applicable valuation or loan loss allowance to be the most relevant indicator of the impact on earnings caused by the fair value measurement. Accordingly, the table above excludes total gains and losses included in earnings for these items. The carrying values are inclusive of the respective valuation or loan loss allowance. (c) The allowance provided for repossessed and foreclosed assets represents any cumulative valuation adjustment recognized to adjust the assets to fair value. Nonrecurring Lower-of-cost or Total gain (loss) included in earnings for the three months ended March 31, 2016 ($ in millions) Level 1 Level 2 Level 3 Total Assets Loans held-for-sale, net $ — $ — $ 39 $ 39 $ — n/m (a) Commercial finance receivables and loans, net (b) Commercial and industrial Automotive — — 17 17 (3 ) n/m (a) Other — — 28 28 (15 ) n/m (a) Total commercial finance receivables and loans, net — — 45 45 (18 ) n/m (a) Other assets Repossessed and foreclosed assets (c) — — 12 12 (3 ) n/m (a) Other — — 6 6 — n/m (a) Total assets $ — $ — $ 102 $ 102 $ (21 ) n/m n/m = not meaningful (a) We consider the applicable valuation or loan loss allowance to be the most relevant indicator of the impact on earnings caused by the fair value measurement. Accordingly, the table above excludes total gains and losses included in earnings for these items. The carrying values are inclusive of the respective valuation or loan loss allowance. (b) Represents the portion of the portfolio specifically impaired during 2016 . The related valuation allowance represents the cumulative adjustment to fair value of those specific receivables. (c) The allowance provided for repossessed and foreclosed assets represents any cumulative valuation adjustment recognized to adjust the assets to fair value. Fair Value Option for Financial Assets We elected the fair value option for an insignificant amount of conforming mortgage loans held-for-sale. We elected the fair value option to mitigate earnings volatility by better matching the accounting for the assets with the related hedges. Our intent in electing fair value measurement was to mitigate a divergence between accounting losses and economic exposure for certain assets and liabilities. Fair Value of Financial Instruments The following table presents the carrying and estimated fair value of financial instruments, except for those recorded at fair value on a recurring basis presented in the previous section of this note titled Recurring Fair Value. When possible, we use quoted market prices to determine fair value. Where quoted market prices are not available, the fair value is internally derived based on appropriate valuation methodologies with respect to the amount and timing of future cash flows and estimated discount rates. However, considerable judgment is required in interpreting current market data to develop the market assumptions and inputs necessary to estimate fair value. As such, the actual amount received to sell an asset or the amount paid to settle a liability could differ from our estimates. Fair value information presented herein was based on information available at March 31, 2017 , and December 31, 2016 . Estimated fair value ($ in millions) Carrying value Level 1 Level 2 Level 3 Total March 31, 2017 Financial assets Held-to-maturity securities $ 1,104 $ — $ 1,063 $ — $ 1,063 Finance receivables and loans, net 117,847 — — 119,420 119,420 Nonmarketable equity investments 833 — 795 59 854 Financial liabilities Deposit liabilities $ 84,486 $ — $ — $ 82,715 $ 82,715 Short-term borrowings 8,371 — — 8,372 8,372 Long-term debt 51,061 — 19,604 33,511 53,115 December 31, 2016 Financial assets Held-to-maturity securities $ 839 $ — $ 789 $ — $ 789 Finance receivables and loans, net 117,800 — — 118,750 118,750 Nonmarketable equity investments 1,046 — 1,012 55 1,067 Financial liabilities Deposit liabilities $ 79,022 $ — $ — $ 78,469 $ 78,469 Short-term borrowings 12,673 — — 12,675 12,675 Long-term debt 54,128 — 22,036 34,084 56,120 The following describes the methodologies and assumptions used to determine fair value for the significant classes of financial instruments. In addition to the valuation methods discussed below, we also followed guidelines for determining whether a market was not active and a transaction was not distressed. We assumed the price that would be received in an orderly transaction (including a market-based return) and not in forced liquidation or distressed sale. • Cash and cash equivalents — Included in cash and cash equivalents are highly liquid investments that are readily convertible to known amounts of cash and which are subject to an insignificant risk of change in value due to interest rate, quoted price, or penalty on withdrawal. Classified as Level 1 under the fair value hierarchy, cash and cash equivalents generally expose us to limited credit risk and are so near maturity that they present insignificant risk of changes in value because of changes in interest rates. Accordingly, the carrying value approximates the fair value of these instruments. • Held-to-maturity securities — Held-to-maturity securities, which consist of asset-backed retained notes and residential mortgage-backed debt securities issued by government agencies, are carried at amortized cost. For fair value disclosure purposes, held-to-maturity securities are classified as Level 2, with fair value based on observable market prices, when available. • Finance receivables and loans, net — With the exception of mortgage loans held-for-investment, the fair value of finance receivables and loans was based on discounted future cash flows using applicable spreads to approximate current rates applicable to each category of finance receivables and loans (an income approach using Level 3 inputs). The carrying value of commercial receivables in certain markets and certain automotive and other receivables for which interest rates reset on a short-term basis with applicable market indices are assumed to approximate fair value either because of the short-term nature or because of the interest rate adjustment feature. The fair value of commercial receivables in other markets was based on discounted future cash flows using applicable spreads to approximate current rates applicable to similar assets in those markets. The fair value of mortgage loans held-for-investment was based on a discounted cash flow basis utilizing cash flow projections from models that utilized prepayment, default, and discount rate assumptions. These valuations consider unique attributes of the loans such as geography, delinquency status, product type, and other factors. • Nonmarketable equity investments — Nonmarketable equity investments primarily include investments in FHLB and FRB stock and other equity investments carried at cost. As a member of the FHLB and FRB, Ally Bank is required to hold FHLB and FRB stock. The stock can be sold only to the FHLB and FRB upon termination of membership, or redeemed at the sole discretion of the FHLB and FRB, respectively. The fair value of FHLB and FRB stock is equal to the stock’s par value since the stock is bought, sold, and/or redeemed at par. FHLB and FRB stock is carried at cost, which generally represents the stock’s par value. • Deposit liabilities — Deposit liabilities represent certain consumer and brokered bank deposits, mortgage escrow deposits, and dealer deposits. The fair value of deposits at Level 3 was estimated by discounting projected cash flows based on discount factors derived from the forward interest rate swap curve. • Short-term borrowings and Long-term debt — Level 2 debt was valued using quoted market prices for similar instruments, when available, or other means for substantiation with observable inputs. Debt valued by discounting projected cash flows using internally derived inputs, such as prepayment speeds and discount rates, was classified as Level 3. • Financial instruments for which carrying value approximates fair value — Certain financial instruments that are not carried at fair value on the consolidated balance sheet are carried at amounts that approximate fair value primarily due to their short term nature and limited credit risk. These instruments include restricted cash, cash collateral, accrued interest receivable, accrued interest payable, trade receivables and payables, and other short term receivables and payables.

Offsetting Assets and Liabiliti

Offsetting Assets and Liabilities Offsetting Assets and Liabilities	3 Months Ended
	Mar. 31, 2017
Offsetting Assets and Liabilities [Abstract]
Offsetting Assets and Liabilities [Text Block]	Offsetting Assets and Liabilities Our derivative contracts and repurchase/reverse repurchase transactions are supported by qualifying master netting and master repurchase agreements. These agreements are legally enforceable bilateral agreements that (1) create a single legal obligation for all individual transactions covered by the agreement to the nondefaulting entity upon an event of default of the counterparty, including bankruptcy, insolvency, or similar proceeding, and (2) provide the nondefaulting entity the right to accelerate, terminate, and close-out on a net basis all transactions under the agreement and to liquidate or set off collateral promptly upon an event of default of the counterparty. To further mitigate the risk of counterparty default related to derivative instruments, we maintain collateral agreements with certain counterparties. The agreements require both parties to maintain collateral in the event the fair values of the derivative financial instruments meet established thresholds. In the event that either party defaults on the obligation, the secured party may seize the collateral. Generally, our collateral arrangements are bilateral such that we and the counterparty post collateral for the value of our total obligation to each other. Contractual terms provide for standard and customary exchange of collateral based on changes in the market value of the outstanding derivatives. The securing party posts additional collateral when their obligation rises or removes collateral when it falls, such that the net replacement cost of the nondefaulting party is covered in the event of counterparty default. In certain instances as it relates to our derivative instruments, we have the option to report derivative assets and liabilities as well as assets and liabilities associated with cash collateral received or delivered that is governed by a master netting agreement on a net basis as long as certain qualifying criteria are met. Similarly, for our repurchase/reverse repurchase transactions, we have the option to report recognized assets and liabilities subject to a master netting agreement on a net basis if certain qualifying criteria are met. At March 31, 2017 , these instruments are reported as gross assets and gross liabilities on the Condensed Consolidated Balance Sheet . The composition of offsetting derivative instruments, financial assets, and financial liabilities was as follows. Gross amounts of recognized assets/(liabilities) Gross amounts offset in the Condensed Consolidated Balance Sheet Net amounts of assets/(liabilities) Gross amounts not offset in the Condensed Consolidated Balance Sheet March 31, 2017 ($ in millions) Financial instruments Collateral Net amount Assets Derivative assets in net asset positions $ 78 $ — $ 78 $ (5 ) $ (8 ) $ 65 Derivative assets in net liability positions 2 — 2 (2 ) — — Total assets (d) $ 80 $ — $ 80 $ (7 ) $ (8 ) $ 65 Liabilities Derivative liabilities in net liability positions $ (76 ) $ — $ (76 ) $ 2 $ 14 $ (60 ) Derivative liabilities in net asset positions (5 ) — (5 ) 5 — — Total derivative liabilities (d) (81 ) — (81 ) 7 14 (60 ) Securities sold under agreements to repurchase (e) (1,146 ) — (1,146 ) — 1,146 — Total liabilities $ (1,227 ) $ — $ (1,227 ) $ 7 $ 1,160 $ (60 ) (a) Financial collateral received/pledged shown as a balance based on the sum of all net asset and liability positions between Ally and each individual derivative counterparty. (b) Amounts disclosed are limited to the financial asset or liability balance and, accordingly, exclude excess collateral received or pledged and noncash collateral received. $6 million of noncash derivative collateral pledged to us was excluded at March 31, 2017 . We do not record such collateral received on our Condensed Consolidated Balance Sheet unless certain conditions are met. (c) Certain agreements grant us the right to sell or pledge the noncash assets we receive as collateral. Noncash collateral pledged to us where the agreement grants us the right to sell or pledge the underlying assets had a fair value of $6 million at March 31, 2017 . We have not sold or pledged any of the noncash collateral received under these agreements as of March 31, 2017 . (d) For additional information on derivative instruments and hedging activities, refer to Note 19 . (e) For additional information on securities sold under agreements to repurchase, refer to Note 14 . Gross amounts of recognized assets/(liabilities) Gross amounts offset in the Condensed Consolidated Balance Sheet Net amounts of assets/(liabilities) Gross amounts not offset in the Condensed Consolidated Balance Sheet December 31, 2016 ( $ in millions ) Financial instruments Collateral Net amount Assets Derivative assets in net asset positions $ 87 $ — $ 87 $ (4 ) $ (9 ) $ 74 Derivative assets in net liability positions 8 — 8 (8 ) — — Total assets (d) $ 95 $ — $ 95 $ (12 ) $ (9 ) $ 74 Liabilities Derivative liabilities in net liability positions $ (91 ) $ — $ (91 ) $ 8 $ 13 $ (70 ) Derivative liabilities in net asset positions (4 ) — (4 ) 4 — — Total derivative liabilities (d) (95 ) — (95 ) 12 13 (70 ) Securities sold under agreements to repurchase (e) (676 ) — (676 ) — 676 — Total liabilities $ (771 ) $ — $ (771 ) $ 12 $ 689 $ (70 ) (a) Financial collateral received/pledged shown as a balance based on the sum of all net asset and liability positions between Ally and each individual derivative counterparty. (b) Amounts disclosed are limited to the financial asset or liability balance and, accordingly, exclude excess collateral received or pledged and noncash collateral received. $6 million of noncash derivative collateral pledged to us was excluded at December 31, 2016. We do not record such collateral received on our Condensed Consolidated Balance Sheet unless certain conditions are met. (c) Certain agreements grant us the right to sell or pledge the noncash assets we receive as collateral. Noncash collateral pledged to us where the agreement grants us the right to sell or pledge the underlying assets had a fair value of $6 million at December 31, 2016. We have not sold or pledged any of the noncash collateral received under these agreements as of December 31, 2016. (d) For additional information on derivative instruments and hedging activities, refer to Note 19 . (e) For additional information on securities sold under agreements to repurchase, refer to Note 14 .

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Segment Reporting Disclosure [Text Block]	Segment Information Operating segments are defined as components of an enterprise that engage in business activity from which revenues are earned and expenses incurred for which discrete financial information is available that is evaluated regularly by our chief operating decision maker in deciding how to allocate resources and in assessing performance. We report our results of operations on a line-of-business basis through four operating segments: Automotive Finance operations, Insurance operations, Mortgage Finance operations, and Corporate Finance operations, with the remaining activity reported in Corporate and Other. The operating segments are determined based on the products and services offered, and reflect the manner in which financial information is currently evaluated by management. The following is a description of each of our reportable operating segments. Automotive Finance operations — Provides U.S.-based automotive financing services to consumers and automotive dealers, and automotive and equipment financing services to companies and municipalities. Our automotive finance services include providing retail installment sales contracts, loans and leases, offering term loans to dealers, financing dealer floorplans and other lines of credit to dealers, warehouse lines to companies, fleet financing, providing financing to companies and municipalities for the purchase or lease of vehicles and equipment, and vehicle remarketing services. Insurance operations — Offers both consumer finance protection and insurance products sold primarily through the automotive dealer channel, and commercial insurance products sold directly to dealers. As part of our focus on offering dealers a broad range of consumer financial and insurance products, we provide vehicle service contracts, vehicle maintenance contracts, and guaranteed asset protection products. We also underwrite select commercial insurance coverages, which primarily insure dealers' wholesale vehicle inventory. Mortgage Finance operations — Primarily consists of the management of a held-for-investment consumer mortgage finance loan portfolio, which includes bulk purchases of high-quality jumbo and low-to-moderate income (LMI) mortgage loans originated by third parties. In late 2016, we introduced our direct mortgage offering, named Ally Home, consisting of a variety of jumbo and conforming fixed- and adjustable-rate mortgage products through a third-party fulfillment partner. Under our current arrangement, conforming mortgages are originated as held-for-sale and sold, while jumbo mortgages are originated as held-for-investment. Servicing is performed by a third party and no mortgage servicing rights are created. Corporate Finance operations — Primarily provides senior secured leveraged cash flow and asset-based loans to mostly U.S.-based middle market companies. Our primary focus is on businesses owned by private equity sponsors with loans typically used for leveraged buyouts, mergers and acquisitions, debt refinancing, restructurings, and working capital. Corporate and Other primarily consists of activity related to centralized corporate treasury activities such as management of the cash and corporate investment securities and loan portfolios, short- and long-term debt, retail and brokered deposit liabilities, derivative instruments, the amortization of the discount associated with new debt issuances and bond exchanges, and the residual impacts of our corporate funds-transfer pricing (FTP) and treasury asset liability management (ALM) activities. Corporate and Other also includes certain equity investments which primarily consist of FHLB and FRB stock, the management of our legacy mortgage portfolio which primarily consists of loans originated prior to January 1, 2009, and reclassifications and eliminations between the reportable operating segments. Additionally, beginning in June 2016, financial information related to TradeKing is included within Corporate and Other. We utilize an FTP methodology for the majority of our business operations. The FTP methodology assigns charge rates and credit rates to classes of assets and liabilities based on expected duration and the benchmark rate curve plus an assumed credit spread. Matching duration allocates interest income and interest expense to these reportable segments so their respective results are insulated from interest rate risk. This methodology is consistent with our ALM practices, which includes managing interest rate risk centrally at a corporate level. The net residual impact of the FTP methodology is included within the results of Corporate and Other. The information presented in our reportable operating segments is based in part on internal allocations, which involve management judgment. Financial information for our reportable operating segments is summarized as follows. Three months ended March 31, ($ in millions) Automotive Finance operations Insurance operations Mortgage Finance operations Corporate Finance operations Corporate and Other Consolidated (a) 2017 Net financing revenue and other interest income $ 892 $ 15 $ 34 $ 34 $ 4 $ 979 Other revenue 101 264 — 18 13 396 Total net revenue 993 279 34 52 17 1,375 Provision for loan losses 268 — 1 6 (4 ) 271 Total noninterest expense 437 239 24 21 57 778 Income (loss) from continuing operations before income tax expense $ 288 $ 40 $ 9 $ 25 $ (36 ) $ 326 Total assets $ 115,154 $ 7,230 $ 8,362 $ 3,438 $ 27,917 $ 162,101 2016 Net financing revenue and other interest income (loss) $ 896 $ 14 $ 20 $ 28 $ (7 ) $ 951 Other revenue 77 254 — 6 39 376 Total net revenue 973 268 20 34 32 1,327 Provision for loan losses 209 — 3 6 2 220 Total noninterest expense 427 218 15 17 33 710 Income (loss) from continuing operations before income tax expense $ 337 $ 50 $ 2 $ 11 $ (3 ) $ 397 Total assets $ 112,289 $ 7,194 $ 7,493 $ 2,839 $ 26,690 $ 156,505 (a) Net financing revenue and other interest income after the provision for loan losses totaled $708 million and $731 million for the three months ended March 31, 2017 , and 2016 , respectively.

Parent and Guarantor Condensed

Parent and Guarantor Condensed Consolidating Financial Statements	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Condensed Financial Statements [Text Block]	Parent and Guarantor Condensed Consolidating Financial Statements Certain of our senior notes issued by the parent are guaranteed by 100% directly owned subsidiaries of Ally (the Guarantors). As of March 31, 2017 , the Guarantors include Ally US LLC and IB Finance Holding Company, LLC (IB Finance), each of which fully and unconditionally guarantee the senior notes on a joint and several basis. The following financial statements present condensed consolidating financial data for (i) Ally Financial Inc. (on a parent company-only basis); (ii) the Guarantors; (iii) the nonguarantor subsidiaries (all other subsidiaries); and (iv) an elimination column for adjustments to arrive at (v) the information for the parent company, the Guarantors, and nonguarantors on a consolidated basis. Investments in subsidiaries are accounted for by the parent company and the Guarantors using the equity-method for this presentation. Results of operations of subsidiaries are therefore classified in the parent company’s and Guarantors’ investment in subsidiaries accounts. The elimination entries set forth in the following condensed consolidating financial statements eliminate distributed and undistributed income of subsidiaries, investments in subsidiaries, and intercompany balances and transactions between the parent, the Guarantors, and nonguarantors. Condensed Consolidating Statements of Comprehensive Income Three months ended March 31, 2017 ($ in millions) Parent Guarantors Nonguarantors Consolidating adjustments Ally consolidated Financing (loss) revenue and other interest income Interest and fees on finance receivables and loans $ (35 ) $ — $ 1,403 $ — $ 1,368 Interest and fees on finance receivables and loans — intercompany 4 — 3 (7 ) — Interest and dividends on investment securities and other earning assets — — 135 (1 ) 134 Interest on cash and cash equivalents 2 — 3 — 5 Interest-bearing cash — intercompany — — 1 (1 ) — Operating leases 3 — 540 — 543 Total financing (loss) revenue and other interest income (26 ) — 2,085 (9 ) 2,050 Interest expense Interest on deposits 1 — 230 — 231 Interest on short-term borrowings 17 — 10 — 27 Interest on long-term debt 281 — 143 — 424 Interest on intercompany debt 4 — 4 (8 ) — Total interest expense 303 — 387 (8 ) 682 Net depreciation expense on operating lease assets 2 — 387 — 389 Net financing revenue (331 ) — 1,311 (1 ) 979 Cash dividends from subsidiaries Nonbank subsidiaries 41 — — (41 ) — Other revenue Insurance premiums and service revenue earned — — 241 — 241 (Loss) gain on mortgage and automotive loans, net (2 ) — 16 — 14 Loss on extinguishment of debt — — (1 ) — (1 ) Other gain on investments, net — — 27 — 27 Other income, net of losses 268 — 224 (377 ) 115 Total other revenue 266 — 507 (377 ) 396 Total net revenue (24 ) — 1,818 (419 ) 1,375 Provision for loan losses 107 — 164 — 271 Noninterest expense Compensation and benefits expense 122 — 163 — 285 Insurance losses and loss adjustment expenses — — 88 — 88 Other operating expenses 288 — 494 (377 ) 405 Total noninterest expense 410 — 745 (377 ) 778 (Loss) income from continuing operations before income tax (benefit) expense and undistributed income (loss) of subsidiaries (541 ) — 909 (42 ) 326 Income tax (benefit) expense from continuing operations (134 ) — 247 — 113 Net (loss) income from continuing operations (407 ) — 662 (42 ) 213 Income (loss) from discontinued operations, net of tax 2 — (1 ) — 1 Undistributed income of subsidiaries Bank subsidiary 389 389 — (778 ) — Nonbank subsidiaries 230 — — (230 ) — Net income 214 389 661 (1,050 ) 214 Other comprehensive income, net of tax 20 5 19 (24 ) 20 Comprehensive income $ 234 $ 394 $ 680 $ (1,074 ) $ 234 Three months ended March 31, 2016 ($ in millions) Parent Guarantors Nonguarantors Consolidating adjustments Ally consolidated Financing (loss) revenue and other interest income Interest and fees on finance receivables and loans $ (38 ) $ — $ 1,273 $ — $ 1,235 Interest and fees on finance receivables and loans — intercompany 3 — 2 (5 ) — Interest and dividends on investment securities and other earning assets — — 102 — 102 Interest on cash and cash equivalents 1 — 2 — 3 Interest-bearing cash — intercompany — — 2 (2 ) — Operating leases 5 — 764 — 769 Total financing (loss) revenue and other interest income (29 ) — 2,145 (7 ) 2,109 Interest expense Interest on deposits 2 — 191 — 193 Interest on short-term borrowings 10 — 3 — 13 Interest on long-term debt 289 — 153 — 442 Interest on intercompany debt 4 — 3 (7 ) — Total interest expense 305 — 350 (7 ) 648 Net depreciation expense on operating lease assets 4 — 506 — 510 Net financing revenue (338 ) — 1,289 — 951 Cash dividends from subsidiaries Nonbank subsidiaries 482 — — (482 ) — Other revenue Insurance premiums and service revenue earned — — 230 — 230 (Loss) gain on mortgage and automotive loans, net (3 ) — 4 — 1 Loss on extinguishment of debt (2 ) — (2 ) — (4 ) Other gain on investments, net — — 54 — 54 Other income, net of losses 374 — 217 (496 ) 95 Total other revenue 369 — 503 (496 ) 376 Total net revenue 513 — 1,792 (978 ) 1,327 Provision for loan losses 60 — 160 — 220 Noninterest expense Compensation and benefits expense 147 — 105 — 252 Insurance losses and loss adjustment expenses — — 73 — 73 Other operating expenses 340 — 542 (497 ) 385 Total noninterest expense 487 — 720 (497 ) 710 (Loss) income from continuing operations before income tax (benefit) expense and undistributed income (loss) of subsidiaries (34 ) — 912 (481 ) 397 Income tax (benefit) expense from continuing operations (43 ) — 193 — 150 Net (loss) income from continuing operations 9 — 719 (481 ) 247 Income (loss) from discontinued operations, net of tax 6 — (3 ) — 3 Undistributed income (loss) of subsidiaries Bank subsidiary 270 270 — (540 ) — Nonbank subsidiaries (35 ) — — 35 — Net income 250 270 716 (986 ) 250 Other comprehensive income, net of tax 146 84 151 (235 ) 146 Comprehensive income $ 396 $ 354 $ 867 $ (1,221 ) $ 396 Condensed Consolidating Balance Sheet March 31, 2017 ($ in millions) Parent (a) Guarantors Nonguarantors (a) Consolidating adjustments Ally consolidated Assets Cash and cash equivalents Noninterest-bearing $ 690 $ — $ 823 $ — $ 1,513 Interest-bearing 800 — 1,989 — 2,789 Interest-bearing — intercompany — — 641 (641 ) — Total cash and cash equivalents 1,490 — 3,453 (641 ) 4,302 Available-for-sale securities 6 — 20,308 (6 ) 20,308 Held-to-maturity securities — — 1,155 (51 ) 1,104 Loans held-for-sale, net — — 1 — 1 Finance receivables and loans, net Finance receivables and loans, net 4,864 — 114,138 — 119,002 Intercompany loans to Bank subsidiary 425 — — (425 ) — Nonbank subsidiaries 1,376 — 456 (1,832 ) — Allowance for loan losses (121 ) — (1,034 ) — (1,155 ) Total finance receivables and loans, net 6,544 — 113,560 (2,257 ) 117,847 Investment in operating leases, net 35 — 10,426 — 10,461 Intercompany receivables from Bank subsidiary 32 — — (32 ) — Nonbank subsidiaries 46 — 255 (301 ) — Investment in subsidiaries Bank subsidiary 18,405 18,405 — (36,810 ) — Nonbank subsidiaries 9,680 — — (9,680 ) — Premiums receivable and other insurance assets — — 1,974 (30 ) 1,944 Other assets 4,275 — 4,764 (2,905 ) 6,134 Total assets $ 40,513 $ 18,405 $ 155,896 $ (52,713 ) $ 162,101 Liabilities Deposit liabilities Noninterest-bearing $ — $ — $ 102 $ — $ 102 Interest-bearing 85 — 84,299 — 84,384 Total deposit liabilities 85 — 84,401 — 84,486 Short-term borrowings 4,901 — 3,470 — 8,371 Long-term debt 20,156 — 30,905 — 51,061 Intercompany debt to Bank subsidiary 51 — — (51 ) — Nonbank subsidiaries 1,097 — 1,807 (2,904 ) — Intercompany payables to Bank subsidiary 127 — — (127 ) — Nonbank subsidiaries 180 — 57 (237 ) — Interest payable 231 — 151 — 382 Unearned insurance premiums and service revenue — — 2,514 — 2,514 Accrued expenses and other liabilities 320 — 4,506 (2,904 ) 1,922 Total liabilities 27,148 — 127,811 (6,223 ) 148,736 Total equity 13,365 18,405 28,085 (46,490 ) 13,365 Total liabilities and equity $ 40,513 $ 18,405 $ 155,896 $ (52,713 ) $ 162,101 (a) Amounts presented are based upon the legal transfer of the underlying assets to VIEs in order to reflect legal ownership. December 31, 2016 ($ in millions) Parent (a) Guarantors Nonguarantors (a) Consolidating adjustments Ally consolidated Assets Cash and cash equivalents Noninterest-bearing $ 720 $ — $ 827 $ — $ 1,547 Interest-bearing 100 — 4,287 — 4,387 Interest-bearing — intercompany — — 401 (401 ) — Total cash and cash equivalents 820 — 5,515 (401 ) 5,934 Trading securities — — 82 (82 ) — Available-for-sale securities — — 19,253 (327 ) 18,926 Held-to-maturity securities — — 839 — 839 Finance receivables and loans, net Finance receivables and loans, net 4,705 — 114,239 — 118,944 Intercompany loans to Bank subsidiary 1,125 — — (1,125 ) — Nonbank subsidiaries 1,779 — 626 (2,405 ) — Allowance for loan losses (115 ) — (1,029 ) — (1,144 ) Total finance receivables and loans, net 7,494 — 113,836 (3,530 ) 117,800 Investment in operating leases, net 42 — 11,428 — 11,470 Intercompany receivables from Bank subsidiary 299 — — (299 ) — Nonbank subsidiaries 107 — 67 (174 ) — Investment in subsidiaries Bank subsidiary 17,727 17,727 — (35,454 ) — Nonbank subsidiaries 10,318 — — (10,318 ) — Premiums receivable and other insurance assets — — 1,936 (31 ) 1,905 Other assets 4,347 — 5,085 (2,578 ) 6,854 Total assets $ 41,154 $ 17,727 $ 158,041 $ (53,194 ) $ 163,728 Liabilities Deposit liabilities Noninterest-bearing $ — $ — $ 84 $ — $ 84 Interest-bearing 167 — 78,771 — 78,938 Total deposit liabilities 167 — 78,855 — 79,022 Short-term borrowings 3,622 — 9,051 — 12,673 Long-term debt 21,798 — 32,330 — 54,128 Intercompany debt to Bank subsidiary 330 — — (330 ) — Nonbank subsidiaries 1,027 — 2,903 (3,930 ) — Intercompany payables to Nonbank subsidiaries 153 — 351 (504 ) — Interest payable 253 — 98 — 351 Unearned insurance premiums and service revenue — — 2,500 — 2,500 Accrued expenses and other liabilities 487 — 3,911 (2,661 ) 1,737 Total liabilities 27,837 — 129,999 (7,425 ) 150,411 Total equity 13,317 17,727 28,042 (45,769 ) 13,317 Total liabilities and equity $ 41,154 $ 17,727 $ 158,041 $ (53,194 ) $ 163,728 (a) Amounts presented are based upon the legal transfer of the underlying assets to VIEs in order to reflect legal ownership. Condensed Consolidating Statement of Cash Flows Three months ended March 31, 2017 ($ in millions) Parent Guarantors Nonguarantors Consolidating adjustments Ally consolidated Operating activities Net cash (used in) provided by operating activities $ (149 ) $ — $ 1,284 $ 40 $ 1,175 Investing activities Purchases of available-for-sale securities — — (2,833 ) — (2,833 ) Proceeds from sales of available-for-sale securities — — 1,045 — 1,045 Proceeds from maturities and repayments of available-for-sale securities — — 589 — 589 Purchases of held-to-maturity securities — — (215 ) — (215 ) Proceeds from maturities and repayments of held-to-maturity securities — — 5 — 5 Net change in investment securities — intercompany 1 — 261 (262 ) — Purchases of loans held-for-investment (15 ) — (390 ) — (405 ) Proceeds from sales of finance receivables and loans originated as held-for-investment — — 1,164 — 1,164 Originations and repayments of loans held-for-investment and other 931 — (1,145 ) (960 ) (1,174 ) Net change in loans — intercompany 1,146 — 170 (1,316 ) — Purchases of operating lease assets — — (893 ) — (893 ) Disposals of operating lease assets 1 — 1,544 — 1,545 Capital contributions to subsidiaries (83 ) — — 83 — Returns of contributed capital 645 — — (645 ) — Net change in restricted cash (27 ) — 385 (3 ) 355 Net change in nonmarketable equity investments — — 213 — 213 Other, net (26 ) — 58 (91 ) (59 ) Net cash provided by (used in) investing activities 2,573 — (42 ) (3,194 ) (663 ) Financing activities Net change in short-term borrowings — third party 1,278 — (5,581 ) — (4,303 ) Net (decrease) increase in deposits (82 ) — 5,533 — 5,451 Proceeds from issuance of long-term debt — third party 330 — 3,196 962 4,488 Repayments of long-term debt — third party (2,870 ) — (4,703 ) — (7,573 ) Net change in debt — intercompany (203 ) — (1,146 ) 1,349 — Repurchase of common stock (169 ) — — — (169 ) Dividends paid — third party (38 ) — — — (38 ) Dividends paid and returns of contributed capital — intercompany — — (686 ) 686 — Capital contributions from parent — — 83 (83 ) — Net cash used in financing activities (1,754 ) — (3,304 ) 2,914 (2,144 ) Effect of exchange-rate changes on cash and cash equivalents — — — — — Net increase (decrease) in cash and cash equivalents 670 — (2,062 ) (240 ) (1,632 ) Cash and cash equivalents at beginning of year 820 — 5,515 (401 ) 5,934 Cash and cash equivalents at March 31, $ 1,490 $ — $ 3,453 $ (641 ) $ 4,302 Three months ended March 31, 2016 ($ in millions) Parent Guarantors Nonguarantors Consolidating adjustments Ally consolidated Operating activities Net cash (used in) provided by operating activities $ (24 ) $ — $ 1,708 $ (482 ) $ 1,202 Investing activities Purchases of available-for-sale securities — — (4,870 ) — (4,870 ) Proceeds from sales of available-for-sale securities — — 4,175 — 4,175 Proceeds from maturities and repayments of available-for-sale securities — — 409 — 409 Purchases of held-to-maturity securities — — (118 ) — (118 ) Purchases of loans held-for-investment — — (1,402 ) — (1,402 ) Proceeds from sales of finance receivables and loans originated as held-for-investment — — 2,594 — 2,594 Originations and repayments of loans held-for-investment and other (292 ) — (392 ) — (684 ) Net change in loans — intercompany 683 — (44 ) (639 ) — Purchases of operating lease assets — — (701 ) — (701 ) Disposals of operating lease assets 2 — 1,533 — 1,535 Capital contributions to subsidiaries (128 ) — — 128 — Returns of contributed capital 223 — — (223 ) — Net change in restricted cash — — 48 — 48 Net change in nonmarketable equity investments — — (315 ) — (315 ) Other, net (32 ) — 12 — (20 ) Net cash provided by investing activities 456 — 929 (734 ) 651 Financing activities Net change in short-term borrowings — third party 187 — (2,926 ) — (2,739 ) Net (decrease) increase in deposits (10 ) — 3,790 — 3,780 Proceeds from issuance of long-term debt — third party 178 — 4,066 — 4,244 Repayments of long-term debt — third party (580 ) — (7,910 ) — (8,490 ) Net change in debt — intercompany (68 ) — (684 ) 752 — Repurchase of common stock (14 ) — — — (14 ) Dividends paid — third party (15 ) — — — (15 ) Dividends paid and returns of contributed capital — intercompany — — (705 ) 705 — Capital contributions from parent — — 128 (128 ) — Net cash used in financing activities (322 ) — (4,241 ) 1,329 (3,234 ) Effect of exchange-rate changes on cash and cash equivalents — — 2 — 2 Net increase (decrease) in cash and cash equivalents 110 — (1,602 ) 113 (1,379 ) Cash and cash equivalents at beginning of year 1,635 — 5,595 (850 ) 6,380 Cash and cash equivalents at March 31, $ 1,745 $ — $ 3,993 $ (737 ) $ 5,001

Contingencies and Other Risks

Contingencies and Other Risks	3 Months Ended
	Mar. 31, 2017
Loss Contingency [Abstract]
Contingencies Disclosure [Text Block]	Contingencies and Other Risks Legal Matters Ally and its subsidiaries, including Ally Bank, are or may be subject to potential liability in connection with pending or threatened legal proceedings and other matters. These legal matters may be formal or informal and include litigation and arbitration with one or more identified claimants, certified or purported class actions with yet-to-be-identified claimants, and regulatory or other governmental information-gathering requests, examinations, investigations, and enforcement proceedings. Our legal matters exist in varying stages of adjudication, arbitration, negotiation, or investigation and span our lines of business and operations. Claims may be based in law or equity—such as those arising under contracts or in tort and those involving banking, consumer-protection, securities, tax, employment, and other laws—and some can present novel legal theories and allege substantial or indeterminate damages. We accrue for a legal matter when a loss becomes probable and the amount of loss can be reasonably estimated. Accruals are evaluated each quarter and may be adjusted, upward or downward, based on our best judgment after consultation with counsel. No assurance exists that our accruals will not need to be adjusted in the future. The course and outcome of legal matters are inherently unpredictable. This is especially so when a matter is still in its early stages, the damages sought are indeterminate or unsupported, significant facts are unclear or disputed, novel questions of law or other meaningful legal uncertainties exist, a request to certify a proceeding as a class action is outstanding or granted, multiple parties are named, or regulatory or other governmental entities are involved. As a result, we cannot state with confidence how or when threatened or pending legal matters will be resolved and what losses may be incurred. Actual losses may be higher or lower than any amounts accrued for those matters, possibly to a significant degree. On the basis of information currently available, advice of counsel, available insurance coverage, and established reserves, it is the opinion of management that, except as described in the next paragraph, the eventual outcome of our existing legal matters will not have a material adverse effect on our consolidated financial condition, results of operations, or cash flows. It is possible, however, that an unfavorable resolution of legal matters may be material to our consolidated financial condition, results of operations, or cash flows in a particular period. Descriptions of our material legal matters follow. In each case, the matter could have material adverse consequences for us, including substantial damages or settlements, injunctions, governmental fines or penalties, and reputational or operational risks. We do not believe, however, that an estimate of reasonably possible losses or a range of reasonably possible losses in excess of established reserves—whether in excess of any related accrual or where no accrual exists—can be made for any of these matters. Securities Litigation In October 2016, a purported class action—Bucks County Employees Retirement Fund v. Ally Financial Inc. et al.—was filed in the Circuit Court for Wayne County in the State of Michigan. This matter was removed to the U.S. District Court for the Eastern District of Michigan on November 18, 2016, and is currently pending there as Case No. 2:16-CV-14104. The complaint alleges material misstatements and omissions in connection with Ally’s initial public offering in April 2014, including a failure to adequately disclose the severity of rising subprime automotive loan delinquency rates, deficient underwriting measures employed in the origination of subprime automotive loans, and aggressive tactics used with low-income borrowers. The request for relief includes an indeterminate amount of damages, fees, and costs and other remedies. In January 2017, another purported class action—National Shopmen Pension Fund v. Ally Financial Inc. et al.—was filed in the Circuit Court for Oakland County in the State of Michigan. This matter was removed to the U.S. District Court for the Eastern District of Michigan on January 30, 2017, and is currently pending there as Case No. 2:17-CV-10289. In March 2017, a third purported class action—James McIntire v. Ally Financial Inc. et al.—was filed in the Circuit Court for Wayne County in the State of Michigan. This matter was removed to the U.S. District Court for the Eastern District of Michigan on March 15, 2017, and is currently pending there as Case No. 2:17-CV-10833. The allegations and requested relief in the National Shopmen Pension Fund and James McIntire complaints are substantially similar to those included in the complaint filed by Bucks County Employees Retirement Fund. We intend to vigorously defend against each of these actions. Automotive Subprime Matters In October 2014, we received a document request from the SEC in connection with its investigation related to subprime automotive finance and related securitization activities. Separately, in December 2014, we received a subpoena from the DOJ requesting similar information. In May 2015 and December 2016, we received information requests from the New York Department of Financial Services requesting similar information. We have cooperated with each of these agencies with respect to these matters. Indirect Automotive Finance Matters In December 2013, Ally Financial Inc. and Ally Bank entered into a Consent Order issued by the U.S. Consumer Financial Protection Bureau (CFPB) and a Consent Order jointly submitted with the DOJ and entered by the U.S. District Court for the Eastern District of Michigan (United States v. Ally Financial Inc. and Ally Bank, Civil Action No. 13-15180), in each case, pertaining to allegations of discrimination involving the automotive finance business. The Consent Orders require Ally to create a compliance plan addressing, at a minimum, the communication of Ally’s expectations of Equal Credit Opportunity Act (ECOA) compliance to our automotive dealer clients, maintenance of Ally’s existing limits on dealer finance income for contracts acquired by Ally, and monitoring for potential discrimination both at the dealer level and within our portfolio of contracts acquired across all of our automotive dealer clients. Ally formed a compliance committee consisting of certain Ally Financial Inc. and Ally Bank directors to oversee Ally’s execution of the Consent Orders’ terms. Ally is required to meet certain stipulations under the Consent Orders, including a requirement to make monetary payments when ongoing remediation targets are not attained. Since 2013, Ally has recognized expenses of approximately $240 million for judgments, fines, and monetary remuneration payments to customers related to the Consent Orders. The Consent Orders terminate, according to their terms, in 2017, and preclude the CFPB and the DOJ from pursuing any potential violations of the ECOA against Ally Financial Inc. or Ally Bank for conduct undertaken pursuant to the Consent Orders during the period of the Consent Orders. If the CFPB or the DOJ were to assert that Ally Financial Inc. or Ally Bank is violating the ECOA after the Consent Orders terminate, further legal proceedings could occur. Other Contingencies Ally and its subsidiaries, including Ally Bank, are or may be subject to potential liability under various other contingent exposures, including indemnification, tax, self-insurance, and other miscellaneous contingencies. We accrue for a contingent exposure when a loss becomes probable and the amount of loss can be reasonably estimated. Accruals are evaluated each quarter and may be adjusted, upward or downward, based on our best judgment. No assurance exists that our accruals will not need to be adjusted in the future, and actual losses may be higher or lower than any amounts accrued for those exposures, possibly to a significant degree. On the basis of information currently available, available insurance coverage, and established reserves, it is the opinion of management that the eventual outcome of our other contingent exposures will not have a material adverse effect on our consolidated financial condition, results of operations, or cash flows. Refer to Note 1 to the Consolidated Financial Statements included in our 2016 Annual Report on Form 10-K for additional information related to our policy for establishing reserves for legal and regulatory matters.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2017
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events Declaration of Quarterly Dividend Payment On April 14, 2017 , the Ally Board of Directors declared a quarterly cash dividend payment of $0.08 per share on all common stock. The dividend is payable on May 15, 2017 , to shareholders of record at the close of business on May 1, 2017.

Description of Business, Basi33

Description of Business, Basis of Presentation, and Changes in Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Our accounting and reporting policies conform to accounting principles generally accepted in the United States of America (GAAP). Additionally, where applicable, the policies conform to the accounting and reporting guidelines prescribed by bank regulatory authorities. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and that affect income and expenses during the reporting period and related disclosures. In developing the estimates and assumptions, management uses all available evidence; however, actual results could differ because of uncertainties associated with estimating the amounts, timing, and likelihood of possible outcomes.
Income Tax, Policy [Policy Text Block]	Income Taxes In calculating the provision for interim income taxes, in accordance with Accounting Standards Codification (ASC) 740, Income Taxes , we apply an estimated annual effective tax rate to year-to-date ordinary income. At the end of each interim period, we estimate the effective tax rate expected to be applicable for the full fiscal year. This method differs from that described in Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K, which describes our annual significant income tax accounting policy and related methodology.
Transfers and Servicing of Financial Assets, Transfers of Financial Assets, Policy [Policy Text Block]	Securitizations and Variable Interest Entities We securitize, transfer, and service consumer and commercial automotive loans and operating leases. Securitization transactions typically involve the use of variable interest entities (VIEs) and are accounted for either as sales or secured borrowings. We may retain economic interests in securitized and sold assets, which are generally in the form of senior or subordinated interests, other residual interests, and servicing rights. In order to conclude whether or not a VIE is required to be consolidated, careful consideration and judgment must be given to our continuing involvement with the variable interest entity. In circumstances where we have both the power to direct the activities of the entity that most significantly impact the entity's performance and the obligation to absorb losses or the right to receive benefits of the entity that could be significant, we would conclude that we would consolidate the entity, which would also preclude us from recording an accounting sale on the transaction. In the case of a consolidated VIE, the accounting is consistent with a secured borrowing, (e.g., we continue to carry the loans and we record the related securitized debt on our Condensed Consolidated Balance Sheet ). In transactions where we are not determined to be the primary beneficiary of the VIE, we must determine whether or not we achieve a sale for accounting purposes. In order to achieve a sale for accounting purposes, the assets being transferred must be legally isolated, not be constrained by restrictions from further transfer, and be deemed to be beyond our control. If we were to fail any of the three criteria for sale accounting, the accounting would be consistent with the preceding paragraph (i.e., a secured borrowing) . Refer to Note 10 to the Condensed Consolidated Financial Statements for discussion on VIEs. Gains or losses on off-balance sheet securitizations take into consideration the fair value of any retained interests including the value of certain servicing assets or liabilities, if any, which are initially recorded at fair value at the date of sale. The estimate of the fair value of the retained interests and servicing requires us to exercise significant judgment about the timing and amount of future cash flows from the interests. Refer to Note 21 to the Condensed Consolidated Financial Statements for a discussion of fair value estimates. Gains or losses on off-balance sheet securitizations and sales are reported in gain on mortgage and automotive loans, net, in our Condensed Consolidated Statement of Comprehensive Income . Retained interests are classified as securities or as other assets depending on their nature. On December 24, 2016, the risk retention rules under the Dodd-Frank Wall Street Reform and Consumer Protection Act (Dodd-Frank Act) of 2010 became effective, requiring us to retain at least five percent of the credit risk of the assets underlying asset-backed securitizations . Our note was updated to address this guidance. We retain servicing responsibilities for all of our consumer and commercial automotive loan and operating lease securitizations. We may receive servicing fees for off-balance sheet securitizations based on the securitized loan balances and certain ancillary fees, all of which are reported in servicing fees in the Condensed Consolidated Statement of Comprehensive Income. Typically, the fee we are paid for servicing consumer automotive finance receivables represents adequate compensation, and consequently, we do not recognize a servicing asset or liability. Whether on- or off-balance sheet, the investors in the securitization trusts generally have no recourse to our assets outside of protections afforded through customary market representation and warranty repurchase provisions. Refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K regarding additional significant accounting policies.
New Accounting Pronouncements, Policy [Text Block]	Recently Adopted Accounting Standards Stock Compensation — Improvements to Employee Share-Based Payment Accounting (ASU 2016-09) As of December 31, 2016, we adopted Accounting Standards Update (ASU) 2016-09. The amendments in this update include changes to several aspects of share-based payment accounting. The amendments allow for an entity-wide accounting policy election to either account for forfeitures as they occur or estimate the number of awards that are expected to vest. We elected to account for forfeitures as they occur. The amendments modify the tax withholding requirements to allow entities to withhold an amount up to the employee’s maximum individual statutory tax rates without resulting in a liability classification of the award as opposed to limiting the withholding to the minimum statutory tax rates as required under previous accounting guidance. The amendments require that all excess tax benefits and tax deficiencies related to share-based payment awards should be recognized in income tax expense or benefit in the income statement in the period in which they occur. The adoption of these amendments did not have a material impact to the financial statements. The amendments also address the classification and presentation of certain items on the cash flow statement. Specifically, cash flows related to excess tax benefits should be classified as an operating activity instead of a financing activity and cash flows related to cash paid to a tax authority by an employer when withholding shares from an employee’s award for tax withholding purposes should be classified as a financing activity. The adoption of the amendment requiring excess tax benefits to be classified as an operating activity did not have a material impact to our Condensed Consolidated Statement of Cash Flows . The adoption of the amendment requiring amounts paid to a tax authority by an employer when withholding shares from an employee’s award for tax withholding purposes to be classified as a financing activity resulted in the reclassification of cash flows in our Condensed Consolidated Statement of Cash Flows for the three months ended March 31, 2016 , of $14 million from operating activities to financing activities. Recently Issued Accounting Standards Revenue from Contracts with Customers (ASU 2014-09) and Revenue from Contracts with Customers — Deferral of the Effective Date (ASU 2015-14) In May 2014, the Financial Accounting Standards Board (FASB) issued ASU 2014-09. The purpose of this guidance is to streamline and consolidate existing revenue recognition principles in GAAP and to converge revenue recognition principles with International Financial Reporting Standards (IFRS). The core principle of the amendments is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to receive in exchange for those goods or services. The amendments include a five step process for consideration of the main principle, guidance on the accounting treatment for costs associated with a contract, and disclosure requirements related to the revenue process. As originally issued, the amendments in ASU 2014-09 were to be effective beginning on January 1, 2017. However, in August 2015, the FASB issued ASU 2015-14, which deferred the effective date of the guidance until January 1, 2018, and permitted early adoption as of the original effective date in ASU 2014-09. The FASB created a transition resource group to work with stakeholders and clarify the new guidance as necessary. The FASB has issued several additional ASUs to clarify guidance and provide implementation support for ASU 2014-09. The clarifying guidance elaborates on the key concepts within ASU 2014-09 and clarifies how those concepts interact with other GAAP requirements. Management has considered these additional ASUs when assessing the overall impact of ASU 2014-09. The amendments to the revenue recognition principles can be applied on adoption either through a full retrospective application or on a modified basis with a cumulative effect adjustment on the date of initial adoption with certain practical expedients. A majority of our revenue streams are not within the scope of this ASU as they are governed by other accounting standards. Management has determined that certain revenue streams and contractual arrangements are in scope of this guidance, including deposit fees, premiums on certain noninsurance contracts, brokering commissions through our insurance operations, remarketing fee income through SmartAuction, and investment advisory fee income through TradeKing. Management does not expect these amendments to impact current revenue recognition patterns for a majority of the in scope revenue streams and contracts. However, we expect that the application of this guidance to noninsurance contracts within our insurance business will result in the deferral of certain amounts we currently recognize as revenue upon the origination of the contract. We do not expect the impact of the new guidance to these specific contracts to be material to the financial statements. Management continues to evaluate whether we will adopt this guidance using the full retrospective approach or the modified retrospective approach. Financial Instruments — Recognition and Measurement of Financial Assets (ASU 2016-01) In January 2016, the FASB issued ASU 2016-01. The amendments in this update modify the requirements related to the measurement of certain financial instruments in the statement of financial condition and results of operations. For equity investments (other than investments accounted for using the equity method), entities must measure such instruments at fair value with changes in fair value recognized in net income. Changes in fair value for available-for-sale equity securities will no longer be recognized through other comprehensive income. Reporting entities may continue to elect to measure equity investments that do not have a readily determinable fair value at cost with adjustments for impairment and observable changes in price. In addition, for a liability (other than a derivative liability) that an entity measures at fair value, any change in fair value related to the instrument-specific credit risk, that is the entity’s own-credit, should be presented separately in other comprehensive income and not as a component of net income. The amendments are effective on January 1, 2018, with early adoption permitted solely for the provisions pertaining to instrument-specific credit risk for liabilities measured at fair value. The amendments must be applied on a modified retrospective basis with a cumulative effect adjustment as of the beginning of the fiscal year of initial adoption. The amendment requiring equity investments to be measured at fair value with changes in fair value recognized in net income will create additional volatility in our consolidated results of operations since changes in fair value for available-for-sale securities will be recognized in net income as opposed to other comprehensive income as required under existing accounting guidance. Management continues to evaluate the impact of the other amendments. However, we do not anticipate the other amendments to have a material impact to our financial statements. Management currently plans to adopt these amendments on January 1, 2018, and expects to use the modified retrospective approach as required. Leases (ASU 2016-02) In February 2016, the FASB issued ASU 2016-02. The amendments in this update primarily replace the existing accounting requirements for operating leases for lessees. Lessee accounting requirements for finance leases and lessor accounting requirements for both operating leases and sales type and direct financing leases (both of which were previously referred to as capital leases) are largely unchanged. The amendments require the lessee of an operating lease to record a balance sheet gross-up upon lease commencement by recognizing a right-of-use asset and lease liability equal to the present value of the lease payments. The right-of-use asset and lease liability should be derecognized in a manner that effectively yields a straight line lease expense over the lease term. In addition to the changes to the lessee operating lease accounting requirements, the amendments also change the types of costs that can be capitalized related to a lease agreement for both lessees and lessors for all types of leases. The amendments also require additional disclosures for all lease types for both lessees and lessors. The amendments are effective on January 1, 2019, with early adoption permitted. The amendments must be applied on a modified retrospective basis with a cumulative adjustment to the beginning of the earliest fiscal year presented in the financial statements in the period of adoption. Management is currently evaluating the impact of these amendments. Upon adoption, we expect to record a balance sheet gross up, reflecting our right-of-use asset and lease liability for our operating leases where we are the lessee (for example, our facility leases). We are currently reviewing our operating lease contracts where we are the lessee to determine the impact of the gross up and the changes to capitalizable costs. We are also reviewing our leases where we are the lessor to determine the impact of the changes to capitalizable costs. Management currently plans to adopt these amendments on January 1, 2019, and expects to use the modified retrospective approach as required. Financial Instruments — Credit Losses (ASU 2016-13) In June 2016, the FASB issued ASU 2016-13. The amendments in this update introduce a new accounting model to measure credit losses for financial assets measured at amortized cost. Credit losses for financial assets measured at amortized cost should be determined based on the total current expected credit losses over the life of the financial asset or group of financial assets. In effect, the financial asset or group of financial assets should be presented at the net amount expected to be collected. Credit losses will no longer be measured as they are incurred for financial assets measured at amortized cost. The amendments also modify the accounting for available-for-sale debt securities whereby credit losses will be recorded through an allowance for credit losses rather than a write-down to the security’s cost basis, which allows for reversals of credit losses when estimated credit losses decline. Credit losses for available-for-sale debt securities should be measured in a manner similar to current GAAP. The amendments are effective on January 1, 2020, with early adoption permitted as of January 1, 2019. The amendments must be applied using a modified retrospective approach with a cumulative-effect adjustment through retained earnings as of the beginning of the fiscal year upon adoption. The new accounting model for credit losses represents a significant departure from existing GAAP, and will likely materially increase the allowance for credit losses with a resulting negative adjustment to retained earnings. Management created a formal working group to govern the implementation of these amendments consisting of key stakeholders from finance, risk, and accounting and is currently evaluating the impact of the amendments. Management currently plans to adopt these amendments on January 1, 2020, and expects to use the modified retrospective approach as required. Statement of Cash Flows — Restricted Cash (ASU 2016-18) In November 2016, the FASB issued ASU 2016-18. The amendments in this update require that amounts classified as restricted cash and restricted cash equivalents be included within the beginning-of-period and end-of-period amounts along with cash and cash equivalents on the statement of cash flows. Prior to this ASU, specific guidance on the presentation of changes in restricted cash and restricted cash equivalents within the statement of cash flows did not exist. The amendments are effective on January 1, 2018, with early adoption permitted. The amendments must be applied retrospectively to all periods presented within the statement of cash flows upon adoption. Management is currently evaluating the impact of these amendments. Receivables — Nonrefundable Fees and Other Costs: Premium Amortization on Purchased Callable Debt Securities (ASU 2017-08) In March 2017, the FASB issued ASU 2017-08. The amendments in this update require premiums on purchased callable debt securities to be amortized to the security’s earliest call date. Prior to this ASU, premiums and discounts on purchased callable debt securities were generally required to be amortized to the security’s maturity date. The amendments do not require an accounting change for securities held at a discount. The amendments are effective on January 1, 2019, with early adoption permitted. The amendments must be applied using a modified retrospective approach with a cumulative-effect adjustment through retained earnings as of the beginning of the fiscal year upon adoption. Management is currently evaluating the impact of these amendments.

Discontinued Operations Discont

Discontinued Operations Discontinued Operations (Policies)	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Discontinued Operations, Policy [Policy Text Block]	Prior to the adoption of ASU 2014-08, which was prospectively applied only to newly identified disposals that qualify as discontinued operations beginning after January 1, 2015, we have classified operations as discontinued when operations and cash flows will be eliminated from our ongoing operations and we do not expect to retain any significant continuing involvement in their operations after the respective sale or disposal transactions. For all periods presented, the operating results for these discontinued operations have been removed from continuing operations and presented separately as discontinued operations, net of tax, in the Condensed Consolidated Statement of Comprehensive Income . The Notes to the Condensed Consolidated Financial Statements have been adjusted to exclude discontinued operations unless otherwise noted.

Acquisitions Acquisitions (Tabl

Acquisitions Acquisitions (Tables)	3 Months Ended
	Mar. 31, 2017
Acquisitions [Abstract]
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	The following table summarizes the allocation of cash consideration paid for TradeKing and the amounts of the identifiable assets acquired and liabilities assumed recognized at the acquisition date. ($ in millions) Purchase price Cash consideration $ 298 Allocation of purchase price to net assets acquired Intangible assets (a) 82 Cash and short-term investments (b) 50 Other assets 14 Deferred tax asset, net 4 Employee compensation and benefits (41 ) Other liabilities (4 ) Goodwill $ 193 (a) We recorded $3 million of amortization on these intangible assets during the three months ended March 31, 2017. (b) Includes $40 million in cash proceeds from the acquisition transaction in order to pay employee compensation and benefits that vested upon acquisition as a result of the change in control.

Discontinued Operations (Tables

Discontinued Operations (Tables)	3 Months Ended
	Mar. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations [Table Text Block]	Select financial information of discontinued operations is summarized below. Three months ended March 31, ($ in millions) 2017 2016 Pretax income $ 1 $ 4 Tax expense — 1

Other Income, Net of Losses (Ta

Other Income, Net of Losses (Tables)	3 Months Ended
	Mar. 31, 2017
Other Nonoperating Income (Expense) [Abstract]
Schedule of Other Nonoperating Income, by Component [Table Text Block]	Details of other income, net of losses, were as follows. Three months ended March 31, ($ in millions) 2017 2016 Remarketing fees $ 29 $ 28 Late charges and other administrative fees 27 25 Servicing fees 16 13 Income from equity-method investments — 6 Other, net 43 23 Total other income, net of losses $ 115 $ 95

Reserves for Insurance Losses38

Reserves for Insurance Losses and Loss Adjustment Expenses Reserves for Insurance Losses and Loss Adjustment Expenses (Tables)	3 Months Ended
	Mar. 31, 2017
Insurance Liability for Unpaid Claims and Claims Adjustment Expenses [Abstract]
Schedule of Liability for Unpaid Claims and Claims Adjustment Expense	The following table shows a rollforward of our reserves for insurance losses and loss adjustment expenses. ($ in millions) 2017 2016 Total gross reserves for insurance losses and loss adjustment expenses at January 1, $ 149 $ 169 Less: Reinsurance recoverable 108 120 Net reserves for insurance losses and loss adjustment expenses at January 1, 41 49 Net insurance losses and loss adjustment expenses incurred related to: Current year 89 77 Prior years (a) (1 ) (4 ) Total net insurance losses and loss adjustment expenses incurred 88 73 Net insurance losses and loss adjustment expenses paid or payable related to: Current year (45 ) (37 ) Prior years (23 ) (22 ) Total net insurance losses and loss adjustment expenses paid or payable (68 ) (59 ) Foreign exchange and other 2 3 Net reserves for insurance losses and loss adjustment expenses at March 31, 63 66 Plus: Reinsurance recoverable 112 118 Total gross reserves for insurance losses and loss adjustment expenses at March 31, $ 175 $ 184 (a) There have been no material adverse changes to the reserve for prior years.

Other Operating Expenses (Table

Other Operating Expenses (Tables)	3 Months Ended
	Mar. 31, 2017
Operating Expenses [Abstract]
Schedule of Other Operating Cost and Expense, by Component [Table Text Block]	Details of other operating expenses were as follows. Three months ended March 31, ($ in millions) 2017 2016 Insurance commissions $ 99 $ 94 Technology and communications 69 66 Lease and loan administration 36 32 Advertising and marketing 30 27 Vehicle remarketing and repossession 28 24 Regulatory and licensing fees 27 21 Professional services 26 24 Premises and equipment depreciation 22 21 Occupancy 12 13 Non-income taxes 8 9 Other 48 54 Total other operating expenses $ 405 $ 385

Investment Securities (Tables)

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Investment [Table Text Block]	Our portfolio of securities includes bonds, equity securities, asset-backed securities, commercial and residential mortgage-backed securities, and other investments. The cost, fair value, and gross unrealized gains and losses on investment securities were as follows. March 31, 2017 December 31, 2016 Amortized cost Gross unrealized Fair value Amortized cost Gross unrealized Fair ($ in millions) gains losses gains losses Available-for-sale securities Debt securities U.S. Treasury $ 2,276 $ 1 $ (52 ) $ 2,225 $ 1,680 $ — $ (60 ) $ 1,620 U.S. States and political subdivisions 803 9 (17 ) 795 794 7 (19 ) 782 Foreign government 143 3 — 146 157 5 — 162 Agency mortgage-backed residential 12,054 31 (223 ) 11,862 10,473 29 (212 ) 10,290 Mortgage-backed residential 2,053 4 (61 ) 1,996 2,162 5 (70 ) 2,097 Mortgage-backed commercial 533 2 (1 ) 534 537 2 (2 ) 537 Asset-backed 1,046 6 (1 ) 1,051 1,396 6 (2 ) 1,400 Corporate debt 1,262 6 (13 ) 1,255 1,452 7 (16 ) 1,443 Total debt securities (a) (b) 20,170 62 (368 ) 19,864 18,651 61 (381 ) 18,331 Equity securities 481 9 (46 ) 444 642 7 (54 ) 595 Total available-for-sale securities $ 20,651 $ 71 $ (414 ) $ 20,308 $ 19,293 $ 68 $ (435 ) $ 18,926 Held-to-maturity securities Debt securities Agency mortgage-backed residential (c) $ 1,052 $ 2 $ (43 ) $ 1,011 $ 839 $ — $ (50 ) $ 789 Asset-backed retained notes 52 — — 52 — — — — Total held-to-maturity securities (d) $ 1,104 $ 2 $ (43 ) $ 1,063 $ 839 $ — $ (50 ) $ 789 (a) Certain entities related to our Insurance operations are required to deposit securities with state regulatory authorities. These deposited securities totaled $12 million and $14 million at March 31, 2017 , and December 31, 2016 , respectively. (b) Investment securities with a fair value of $3,235 million and $4,881 million at March 31, 2017 , and December 31, 2016 , respectively, were pledged to secure advances from the Federal Home Loan Bank (FHLB), short-term borrowings or repurchase agreements and for other purposes as required by contractual obligation or law. Under these agreements, Ally has granted the counterparty the right to sell or pledge $1,257 million and $737 million of the underlying investment securities at March 31, 2017 , and December 31, 2016 , respectively. (c) Agency-backed residential mortgage-backed debt securities are held for liquidity purposes. (d) Held-to-maturity securities are recorded at amortized cost. Held-to-maturity securities with a fair value of $0 million and $87 million at March 31, 2017, and December 31, 2016 , respectively, were pledged to secure advances from the FHLB
Investments Classified by Contractual Maturity Date [Table Text Block]	The maturity distribution of investment securities outstanding is summarized in the following tables. Call or prepayment options may cause actual maturities to differ from contractual maturities. Total Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years ($ in millions) Amount Yield Amount Yield Amount Yield Amount Yield Amount Yield March 31, 2017 Fair value of available-for-sale debt securities (a) U.S. Treasury $ 2,225 1.8 % $ — — % $ 262 1.8 % $ 1,963 1.8 % $ — — % U.S. States and political subdivisions 795 3.1 66 2.4 34 2.5 175 2.9 520 3.3 Foreign government 146 2.5 — — 66 2.7 80 2.4 — — Agency mortgage-backed residential 11,862 3.0 — — — — 3 2.9 11,859 3.0 Mortgage-backed residential 1,996 2.9 — — — — — — 1,996 2.9 Mortgage-backed commercial 534 2.8 — — — — 3 2.8 531 2.8 Asset-backed 1,051 2.9 — — 829 2.9 59 3.2 163 2.6 Corporate debt 1,255 2.9 99 2.1 642 2.6 468 3.2 46 4.7 Total available-for-sale debt securities $ 19,864 2.8 $ 165 2.2 $ 1,833 2.6 $ 2,751 2.2 $ 15,115 3.0 Amortized cost of available-for-sale debt securities $ 20,170 $ 165 $ 1,826 $ 2,806 $ 15,373 Amortized cost of held-to-maturity securities Agency mortgage-backed residential 1,052 3.0 % — — % — — % — — % 1,052 3.0 % Asset-backed retained notes 52 1.5 10 0.8 40 1.6 2 2.7 — — Total held-to-maturity securities $ 1,104 2.9 $ 10 0.8 $ 40 1.6 $ 2 2.7 $ 1,052 3.0 December 31, 2016 Fair value of available-for-sale debt securities (a) U.S. Treasury $ 1,620 1.7 % $ 2 4.6 % $ 60 1.6 % $ 1,558 1.7 % $ — — % U.S. States and political subdivisions 782 3.1 64 1.7 29 2.3 172 2.8 517 3.4 Foreign government 162 2.6 — — 58 2.8 104 2.4 — — Agency mortgage-backed residential 10,290 2.9 — — — — 29 2.6 10,261 2.9 Mortgage-backed residential 2,097 2.9 — — — — — — 2,097 2.9 Mortgage-backed commercial 537 2.6 — — — — 3 2.8 534 2.6 Asset-backed 1,400 2.8 — — 1,059 2.8 143 3.2 198 2.6 Corporate debt 1,443 2.8 72 2.2 840 2.6 489 3.2 42 4.7 Total available-for-sale debt securities $ 18,331 2.8 $ 138 2.0 $ 2,046 2.7 $ 2,498 2.2 $ 13,649 2.9 Amortized cost of available-for-sale debt securities $ 18,651 $ 138 $ 2,040 $ 2,563 $ 13,910 Amortized cost of held-to-maturity securities $ 839 2.9 % $ — — % $ — — % $ — — % $ 839 2.9 % (a) Yield is calculated using the effective yield of each security at the end of the period, weighted based on the market value. The effective yield considers the contractual coupon and amortized cost, and excludes expected capital gains and losses
Investment Income [Table Text Block]	The following table presents interest and dividends on investment securities. Three months ended March 31, ($ in millions) 2017 2016 Taxable interest $ 119 $ 94 Taxable dividends 2 4 Interest and dividends exempt from U.S. federal income tax 5 4 Interest and dividends on investment securities $ 126 $ 102
Schedule of Unrealized Loss on Investments [Table Text Block]	The table below summarizes available-for-sale securities in an unrealized loss position in accumulated other comprehensive income. Based on the assessment of whether such losses were deemed to be other-than-temporary, we believe that the unrealized losses are not indicative of an other-than-temporary impairment of these securities. As of March 31, 2017 , we did not have the intent to sell the debt securities with an unrealized loss position in accumulated other comprehensive income, it is not more likely than not that we will be required to sell these securities before recovery of their amortized cost basis, and we expect to recover the entire amortized cost basis of the securities. As of March 31, 2017 , we had the ability and intent to hold equity securities with an unrealized loss position in accumulated other comprehensive income, and it is not more likely than not that we will be required to sell these securities before recovery of their amortized cost basis. As a result, we believe that the securities with an unrealized loss position in accumulated other comprehensive income are not considered to be other-than-temporarily impaired at March 31, 2017 . Refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K for additional information related to investment securities and our methodology for evaluating potential other-than-temporary impairments. March 31, 2017 December 31, 2016 Less than 12 months 12 months or longer Less than 12 months 12 months or longer $ in millions) Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss Available-for-sale securities Debt securities U.S. Treasury $ 2,070 $ (52 ) $ — $ — $ 1,612 $ (60 ) $ — $ — U.S. States and political subdivisions 435 (16 ) 26 (1 ) 524 (19 ) — — Foreign government 13 — — — 38 — — — Agency mortgage-backed residential 8,874 (209 ) 531 (14 ) 8,052 (196 ) 587 (16 ) Mortgage-backed residential 768 (16 ) 816 (45 ) 813 (17 ) 860 (53 ) Mortgage-backed commercial 79 (1 ) 77 — 47 (1 ) 149 (1 ) Asset-backed 175 — 134 (1 ) 375 (2 ) 127 — Corporate debt 565 (11 ) 46 (2 ) 744 (14 ) 46 (2 ) Total temporarily impaired debt securities 12,979 (305 ) 1,630 (63 ) 12,205 (309 ) 1,769 (72 ) Temporarily impaired equity securities 72 (6 ) 162 (40 ) 151 (8 ) 269 (46 ) Total temporarily impaired available-for-sale securities $ 13,051 $ (311 ) $ 1,792 $ (103 ) $ 12,356 $ (317 ) $ 2,038 $ (118 )

Finance Receivables and Loans41

Finance Receivables and Loans, Net (Tables)	3 Months Ended
	Mar. 31, 2017
Loans and Leases Receivable, Net Amount [Abstract]
Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]	The composition of finance receivables and loans reported at gross carrying value was as follows. ($ in millions) March 31, 2017 December 31, 2016 Consumer automotive (a) $ 65,663 $ 65,793 Consumer mortgage Mortgage Finance (b) 8,331 8,294 Mortgage — Legacy (c) 2,606 2,756 Total consumer mortgage 10,937 11,050 Total consumer 76,600 76,843 Commercial Commercial and industrial Automotive 34,911 35,041 Other 3,499 3,248 Commercial real estate — Automotive 3,992 3,812 Total commercial 42,402 42,101 Total finance receivables and loans (d) $ 119,002 $ 118,944 (a) Includes $34 million and $43 million of fair value adjustment for loans in hedge accounting relationships at March 31, 2017 , and December 31, 2016 , respectively. Refer to Note 19 for additional information. (b) Includes loans originated as interest-only mortgage loans of $26 million and $30 million at March 31, 2017 , and December 31, 2016 , respectively, 3% of which are expected to start principal amortization in 2017 , none in 2018 , 37% in 2019 , 42% in 2020 , and none thereafter. (c) Includes loans originated as interest-only mortgage loans of $653 million and $714 million at March 31, 2017 , and December 31, 2016 , respectively, 17% of which are expected to start principal amortization in 2017 , 2% in 2018 , none in 2019 , none in 2020 , and 1% thereafter. (d) Totals include net increases of $393 million and $359 million at March 31, 2017 , and December 31, 2016 , respectively, for unearned income, unamortized premiums and discounts, and deferred fees and costs.
Allowance for Credit Losses on Financing Receivables [Table Text Block]	The following tables present an analysis of the activity in the allowance for loan losses on finance receivables and loans. Three months ended March 31, 2017 ($ in millions) Consumer automotive Consumer mortgage Commercial Total Allowance at January 1, 2017 $ 932 $ 91 $ 121 $ 1,144 Charge-offs (a) (341 ) (9 ) — (350 ) Recoveries 90 7 — 97 Net charge-offs (251 ) (2 ) — (253 ) Provision for loan losses 267 (3 ) 7 271 Other (b) (7 ) — — (7 ) Allowance at March 31, 2017 $ 941 $ 86 $ 128 $ 1,155 Allowance for loan losses at March 31, 2017 Individually evaluated for impairment $ 32 $ 33 $ 24 $ 89 Collectively evaluated for impairment 909 53 104 1,066 Finance receivables and loans at gross carrying value Ending balance $ 65,663 $ 10,937 $ 42,402 $ 119,002 Individually evaluated for impairment 388 249 120 757 Collectively evaluated for impairment 65,275 10,688 42,282 118,245 (a) Represents the amount of the gross carrying value directly written-off. For consumer and commercial loans, the loss from a charge-off is measured as the difference between the gross carrying value of a loan and the fair value of the collateral, less costs to sell. Refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K for more information regarding our charge-off policies. (b) Primarily related to the transfer of finance receivables and loans from held-for-investment to held-for-sale. Three months ended March 31, 2016 ($ in millions) Consumer automotive Consumer mortgage Commercial Total Allowance at January 1, 2016 $ 834 $ 114 $ 106 $ 1,054 Charge-offs (a) (253 ) (10 ) — (263 ) Recoveries 80 4 — 84 Net charge-offs (173 ) (6 ) — (179 ) Provision for loan losses 207 7 6 220 Other (b) (18 ) — — (18 ) Allowance at March 31, 2016 $ 850 $ 115 $ 112 $ 1,077 Allowance for loan losses at March 31, 2016 Individually evaluated for impairment $ 25 $ 43 $ 18 $ 86 Collectively evaluated for impairment 825 72 94 991 Finance receivables and loans at gross carrying value Ending balance $ 63,013 $ 10,675 $ 37,188 $ 110,876 Individually evaluated for impairment 337 261 90 688 Collectively evaluated for impairment 62,676 10,414 37,098 110,188 (a) Represents the amount of the gross carrying value directly written-off. For consumer and commercial loans, the loss from a charge-off is measured as the difference between the gross carrying value of a loan and the fair value of the collateral, less costs to sell. Refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K for more information regarding our charge-off policies. (b) Primarily related to the transfer of finance receivables and loans from held-for-investment to held-for-sale.
Schedule Of Sales Of Financing Receivables And Loans [Table Text Block]	The following table presents information about significant sales of finance receivables and loans and transfers of finance receivables and loans from held-for-investment to held-for-sale. Three months ended March 31, ($ in millions) 2017 2016 Consumer automotive $ 1,213 $ 2,599 Consumer mortgage 3 2 Total sales and transfers $ 1,216 $ 2,601
Schedule of Purchases of Financing Receivables and Loans [Table Text Block]	The following table presents information about significant purchases of finance receivables and loans. Three months ended March 31, ($ in millions) 2017 2016 Consumer automotive $ 68 $ — Consumer mortgage 327 1,370 Total purchases of finance receivables and loans $ 395 $ 1,370
Past Due Financing Receivables [Table Text Block]	The following table presents an analysis of our past due finance receivables and loans recorded at gross carrying value. ($ in millions) 30–59 days past due 60–89 days past due 90 days or more past due Total past due Current Total finance receivables and loans March 31, 2017 Consumer automotive $ 1,346 $ 308 $ 263 $ 1,917 $ 63,746 $ 65,663 Consumer mortgage Mortgage Finance 30 2 7 39 8,292 8,331 Mortgage — Legacy 33 14 57 104 2,502 2,606 Total consumer mortgage 63 16 64 143 10,794 10,937 Total consumer 1,409 324 327 2,060 74,540 76,600 Commercial Commercial and industrial Automotive — — 6 6 34,905 34,911 Other — — — — 3,499 3,499 Commercial real estate — Automotive — — — — 3,992 3,992 Total commercial — — 6 6 42,396 42,402 Total consumer and commercial $ 1,409 $ 324 $ 333 $ 2,066 $ 116,936 $ 119,002 December 31, 2016 Consumer automotive $ 1,850 $ 428 $ 302 $ 2,580 $ 63,213 $ 65,793 Consumer mortgage Mortgage Finance 39 6 4 49 8,245 8,294 Mortgage — Legacy 45 18 57 120 2,636 2,756 Total consumer mortgage 84 24 61 169 10,881 11,050 Total consumer 1,934 452 363 2,749 74,094 76,843 Commercial Commercial and industrial Automotive 3 — 7 10 35,031 35,041 Other — — — — 3,248 3,248 Commercial real estate — Automotive — — — — 3,812 3,812 Total commercial 3 — 7 10 42,091 42,101 Total consumer and commercial $ 1,937 $ 452 $ 370 $ 2,759 $ 116,185 $ 118,944
Schedule of Financing Receivables, Non Accrual Status [Table Text Block]	The following table presents the gross carrying value of our finance receivables and loans on nonaccrual status. ($ in millions) March 31, 2017 December 31, 2016 Consumer automotive $ 573 $ 598 Consumer mortgage Mortgage Finance 10 10 Mortgage — Legacy 95 89 Total consumer mortgage 105 99 Total consumer 678 697 Commercial Commercial and industrial Automotive 34 33 Other 81 84 Commercial real estate — Automotive 5 5 Total commercial 120 122 Total consumer and commercial finance receivables and loans $ 798 $ 819
Financing Receivable Credit Quality Indicators - Performing and Nonperforming [Table Text Block]	The following table presents performing and nonperforming credit quality indicators in accordance with our internal accounting policies for our consumer finance receivables and loans recorded at gross carrying value. Nonperforming loans include finance receivables and loans on nonaccrual status when the principal or interest has been delinquent for 90 days or when full collection is not expected. Refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K for additional information. March 31, 2017 December 31, 2016 ($ in millions) Performing Nonperforming Total Performing Nonperforming Total Consumer automotive $ 65,090 $ 573 $ 65,663 $ 65,195 $ 598 $ 65,793 Consumer mortgage Mortgage Finance 8,321 10 8,331 8,284 10 8,294 Mortgage — Legacy 2,511 95 2,606 2,667 89 2,756 Total consumer mortgage 10,832 105 10,937 10,951 99 11,050 Total consumer $ 75,922 $ 678 $ 76,600 $ 76,146 $ 697 $ 76,843
Schedule Of Pass And Criticized Credit Quality Indicators Of Finance Receivables [Table Text Block]	The following table presents pass and criticized credit quality indicators based on regulatory definitions for our commercial finance receivables and loans recorded at gross carrying value. March 31, 2017 December 31, 2016 ($ in millions) Pass Criticized (a) Total Pass Criticized (a) Total Commercial and industrial Automotive $ 32,878 $ 2,033 $ 34,911 $ 33,160 $ 1,881 $ 35,041 Other 2,814 685 3,499 2,597 651 3,248 Commercial real estate — Automotive 3,816 176 3,992 3,653 159 3,812 Total commercial $ 39,508 $ 2,894 $ 42,402 $ 39,410 $ 2,691 $ 42,101 (a) Includes loans classified as special mention, substandard, or doubtful. These classifications are based on regulatory definitions and generally represent loans within our portfolio that have a higher default risk or have already defaulted.
Impaired Financing Receivables [Table Text Block]	The following table presents information about our impaired finance receivables and loans. ( $ in millions ) Unpaid principal balance (a) Gross carrying value Impaired with no allowance Impaired with an allowance Allowance for impaired loans March 31, 2017 Consumer automotive $ 422 $ 388 $ 124 $ 264 $ 32 Consumer mortgage Mortgage Finance 8 8 4 4 — Mortgage — Legacy 245 241 56 185 33 Total consumer mortgage 253 249 60 189 33 Total consumer 675 637 184 453 65 Commercial Commercial and industrial Automotive 34 34 7 27 2 Other 98 81 19 62 21 Commercial real estate — Automotive 5 5 — 5 1 Total commercial 137 120 26 94 24 Total consumer and commercial finance receivables and loans $ 812 $ 757 $ 210 $ 547 $ 89 December 31, 2016 Consumer automotive $ 407 $ 370 $ 131 $ 239 $ 28 Consumer mortgage Mortgage Finance 8 8 3 5 — Mortgage — Legacy 243 239 56 183 34 Total consumer mortgage 251 247 59 188 34 Total consumer 658 617 190 427 62 Commercial Commercial and industrial Automotive 33 33 7 26 3 Other 99 84 — 84 19 Commercial real estate — Automotive 5 5 2 3 1 Total commercial 137 122 9 113 23 Total consumer and commercial finance receivables and loans $ 795 $ 739 $ 199 $ 540 $ 85 (a) Adjusted for charge-offs.
Schedule of Average Balance And Interest Income Of Impaired Finance Receivables [Table Text Block]	The following table presents average balance and interest income for our impaired finance receivables and loans. 2017 2016 Three months ended March 31, ($ in millions) Average balance Interest income Average balance Interest income Consumer automotive $ 379 $ 5 $ 326 $ 4 Consumer mortgage Mortgage Finance 8 — 9 — Mortgage — Legacy 241 2 255 2 Total consumer mortgage 249 2 264 2 Total consumer 628 7 590 6 Commercial Commercial and industrial Automotive 33 — 23 — Other 83 — 49 1 Commercial real estate — Automotive 5 — 6 — Total commercial 121 — 78 1 Total consumer and commercial finance receivables and loans $ 749 $ 7 $ 668 $ 7
Troubled Debt Restructurings on Financing Receivables [Table Text Block]	The following table presents information related to finance receivables and loans recorded at gross carrying value modified in connection with a TDR during the period. 2017 2016 Three months ended March 31, ($ in millions) Number of loans Pre-modification gross carrying value Post-modification gross carrying value Number of loans Pre-modification gross carrying value Post-modification gross carrying value Consumer automotive 6,447 $ 115 $ 99 5,622 $ 89 $ 76 Consumer mortgage Mortgage Finance 1 — — 1 1 1 Mortgage — Legacy 53 12 12 31 4 4 Total consumer mortgage 54 12 12 32 5 5 Total consumer 6,501 127 111 5,654 94 81 Commercial Commercial and industrial Automotive — — — — — — Other 1 23 23 — — — Commercial real estate — Automotive — — — — — — Total commercial 1 23 23 — — — Total consumer and commercial finance receivables and loans 6,502 $ 150 $ 134 5,654 $ 94 $ 81
Finance receivables and loans redefaulted during the period [Table Text Block]	The following table presents information about finance receivables and loans recorded at gross carrying value that have redefaulted during the reporting period and were within 12 months or less of being modified as a TDR. Redefault is when finance receivables and loans meet the requirements for evaluation under our charge-off policy (refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K for additional information) except for commercial finance receivables and loans, where redefault is defined as 90 days past due. 2017 2016 Three months ended March 31, ($ in millions) Number of loans Gross carrying value Charge-off amount Number of loans Gross carrying value Charge-off amount Consumer automotive 1,989 $ 24 $ 16 1,800 $ 23 $ 12 Consumer mortgage Mortgage Finance 1 1 — — — — Mortgage — Legacy — — — 1 — — Total consumer finance receivables and loans 1,990 $ 25 $ 16 1,801 $ 23 $ 12

Investment in Operating Lease42

Investment in Operating Leases, Net (Tables)	3 Months Ended
	Mar. 31, 2017
Leases, Operating [Abstract]
Schedule of Property Subject to or Available for Operating Lease [Table Text Block]	Investments in operating leases were as follows. ($ in millions) March 31, 2017 December 31, 2016 Vehicles $ 13,240 $ 14,584 Accumulated depreciation (2,779 ) (3,114 ) Investment in operating leases, net $ 10,461 $ 11,470
Depreciation Expense On Operating Lease Assets [Table Text Block]	Depreciation expense on operating lease assets includes remarketing gains and losses recognized on the sale of operating lease assets. The following summarizes the components of depreciation expense on operating lease assets. Three months ended March 31, ($ in millions) 2017 2016 Depreciation expense on operating lease assets (excluding remarketing gains and losses) $ 386 $ 565 Remarketing losses (gains) 3 (55 ) Net depreciation expense on operating lease assets $ 389 $ 510

Securitizations and Variable 43

Securitizations and Variable Interest Entities (Tables)	3 Months Ended
	Mar. 31, 2017
Securitizations And Variable Interest Entities [Abstract]
Schedule of Variable Interest Entities [Table Text Block]	The following table presents our involvement in consolidated and nonconsolidated VIEs in which we hold variable interests. For additional detail related to the assets and liabilities of consolidated variable interest entities refer to the Condensed Consolidated Balance Sheet. ($ in millions) Carrying value of total assets Carrying value of total liabilities Assets sold to Maximum exposure to March 31, 2017 On-balance sheet variable interest entities Consumer automotive $ 19,632 (b) $ 8,298 (c) Commercial automotive 14,113 5,109 Off-balance sheet variable interest entities Consumer automotive 79 (d) — $ 3,571 $ 3,650 (e) Commercial other 505 (f) 205 (g) — 695 (h) Total $ 34,329 $ 13,612 $ 3,571 $ 4,345 December 31, 2016 On-balance sheet variable interest entities Consumer automotive $ 20,869 (b) $ 8,557 (c) Commercial automotive 16,278 4,764 Off-balance sheet variable interest entities Consumer automotive 24 (d) — $ 2,899 $ 2,923 (e) Commercial other 460 (f) 169 (g) — 651 (h) Total $ 37,631 $ 13,490 $ 2,899 $ 3,574 (a) Asset values represent the current unpaid principal balance of outstanding consumer finance receivables and loans within the VIEs. (b) Includes $9.2 billion and $9.6 billion of assets that are not encumbered by VIE beneficial interests held by third parties at March 31, 2017 , and December 31, 2016 , respectively. Ally or consolidated affiliates hold the interests in these assets, which eliminate in consolidation. (c) Includes $64 million and $50 million of liabilities due to consolidated affiliates at March 31, 2017 , and December 31, 2016 , respectively. These liabilities are not obligations to third-party beneficial interest holders. These liabilities are secured by a portion of the unencumbered assets and eliminate in consolidation. (d) Includes $52 million classified as held-to-maturity securities and $27 million classified as other assets at March 31, 2017 . Of the total amount at March 31, 2017 , $53 million represents retained notes and certificated residual interests. These assets represent our compliance with the risk retention rules under the Dodd-Frank Act, requiring us to retain at least five percent of the credit risk of the assets underlying asset-backed securitizations , which became effective on December 24, 2016. Amounts at December 31, 2016 , are classified as other assets. (e) Maximum exposure to loss represents the current unpaid principal balance of outstanding loans, retained notes, certificated residual interests, as well as certain noncertificated interests retained from the sale of automotive finance receivables. This measure is based on the very unlikely event that all of our sold loans have defects that would trigger a representation and warranty provision and the underlying collateral supporting the loans becomes worthless. This required disclosure is not an indication of our expected loss. (f) Amounts are classified as other assets. (g) Amounts are classified as accrued expenses and other liabilities. (h) For certain nonconsolidated affordable housing entities, maximum exposure to loss represents the yield we guaranteed investors through long-term guarantee contracts. The amount disclosed is based on the unlikely event that the underlying properties cease generating yield to investors and the yield delivered to investors in the form of low income tax housing credits is recaptured. For nonconsolidated equity investments, maximum exposure to loss represents our outstanding investment, additional committed capital, and low income housing tax credits subject to recapture. The amount disclosed is based on the unlikely event that our committed capital is funded, our investments become worthless, and the tax credits previously delivered to us are recaptured. This required disclosure is not an indication of our expected loss.
Schedule Of Cash Flow Received And Paid To Nonconsolidated Securitization Entities [Table Text Block]	The following table summarizes cash flows received and paid related to securitization entities and asset-backed financings where the transfer is accounted for as a sale and we have a continuing involvement with the transferred assets (e.g., servicing) that were outstanding during the three months ended March 31, 2017 , and 2016 . Additionally, this table contains information regarding cash flows received from and paid to nonconsolidated securitization entities that existed during each period. Three months ended March 31, ($ in millions) Consumer automotive 2017 Cash proceeds from transfers completed during the period $ 1,138 Servicing fees 9 Other cash flows 2 2016 Cash proceeds from transfers completed during the period $ 1,025 Servicing fees 8 Other cash flows 2
Schedule of Quantitative Information and Net Credit Losses about Securitized and Other Financial Assets Managed Together [Table Text Block]	The following tables represent on-balance sheet loans held-for-sale and finance receivables and loans, off-balance sheet securitizations, and whole-loan sales where we have continuing involvement. The tables present quantitative information about delinquencies and net credit losses. Total Amount Amount 60 days or more ($ in millions) March 31, 2017 December 31, 2016 March 31, 2017 December 31, 2016 On-balance sheet loans Consumer automotive $ 65,663 $ 65,793 $ 571 $ 730 Consumer mortgage 10,938 11,050 80 85 Commercial automotive 38,903 38,853 6 7 Commercial other 3,499 3,248 — — Total on-balance sheet loans 119,003 118,944 657 822 Off-balance sheet securitization entities Consumer automotive 3,067 2,392 12 13 Total off-balance sheet securitization entities 3,067 2,392 12 13 Whole-loan sales (a) 2,787 3,164 5 6 Total $ 124,857 $ 124,500 $ 674 $ 841 (a) Whole-loan sales are not part of a securitization transaction, but represent consumer automotive pools of loans sold to third-party investors. Net credit losses Three months ended March 31, ($ in millions) 2017 2016 On-balance sheet loans Consumer automotive $ 251 $ 173 Consumer mortgage 2 6 Total on-balance sheet loans 253 179 Off-balance sheet securitization entities Consumer automotive 3 2 Total off-balance sheet securitization entities 3 2 Whole-loan sales (a) 1 — Total $ 257 $ 181 (a) Whole-loan sales are not part of a securitization transaction, but represent consumer automotive pools of loans sold to third-party investors.

Servicing Activities (Tables)

Servicing Activities (Tables)	3 Months Ended
	Mar. 31, 2017
Servicing Asset [Abstract]
Schedule Of Total Serviced Automobile Loans Outstanding [Table Text Block]	The current unpaid principal balance and any related unamortized deferred fees and costs of total serviced automotive finance loans and leases outstanding were as follows. ($ in millions) March 31, 2017 December 31, 2016 On-balance sheet automotive finance loans and leases Consumer automotive $ 65,464 $ 65,646 Commercial automotive 38,903 38,853 Operating leases 10,332 11,311 Other 67 67 Off-balance sheet automotive finance loans Securitizations 3,103 2,412 Whole-loan 2,824 3,191 Total serviced automotive finance loans and leases $ 120,693 $ 121,480

Other Assets (Tables)

Other Assets (Tables)	3 Months Ended
	Mar. 31, 2017
Other Assets [Abstract]
Schedule of Other Assets [Table Text Block]	The components of other assets were as follows. ($ in millions) March 31, 2017 December 31, 2016 Property and equipment at cost $ 939 $ 901 Accumulated depreciation (542 ) (525 ) Net property and equipment 397 376 Restricted cash collections for securitization trusts (a) 1,359 1,694 Net deferred tax assets 900 994 Nonmarketable equity investments (b) 833 1,046 Accrued interest and rent receivables 457 476 Goodwill (c) 240 240 Other accounts receivable 165 100 Cash reserve deposits held-for-securitization trusts (d) 164 184 Cash collateral placed with counterparties 119 167 Restricted cash and cash equivalents 111 111 Fair value of derivative contracts in receivable position (e) 80 95 Other assets 1,309 1,371 Total other assets $ 6,134 $ 6,854 (a) Represents cash collections from customer payments on securitized receivables. These funds are distributed to investors as payments on the related secured debt. (b) Includes investments in FHLB stock of $359 million and $577 million at March 31, 2017 , and December 31, 2016 , respectively; and Federal Reserve Bank (FRB) stock of $435 million at both March 31, 2017 , and December 31, 2016 . (c) Includes goodwill of $27 million at our Insurance operations at both March 31, 2017 , and December 31, 2016 ; $193 million within Corporate and Other at both March 31, 2017 , and December 31, 2016 ; and $20 million within Automotive Finance operations at both March 31, 2017 , and December 31, 2016 . No changes to the carrying amount of goodwill were recorded during the three months ended March 31, 2017 . (d) Represents credit enhancement in the form of cash reserves for various securitization transactions. (e) For additional information on derivative instruments and hedging activities, refer to Note 19 .

Deposit Liabilities (Tables)

Deposit Liabilities (Tables)	3 Months Ended
	Mar. 31, 2017
Deposits [Abstract]
Schedule of Deposit Liabilities [Table Text Block]	Deposit liabilities consisted of the following. ( $ in millions ) March 31, 2017 December 31, 2016 Noninterest-bearing deposits $ 102 $ 84 Interest-bearing deposits Savings and money market checking accounts 51,150 46,976 Certificates of deposit 33,148 31,795 Dealer deposits 86 167 Total deposit liabilities $ 84,486 $ 79,022

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Schedule of Short-term Debt [Table Text Block]	The following table presents the composition of our short-term borrowings portfolio. March 31, 2017 December 31, 2016 ($ in millions) Unsecured Secured (a) Total Unsecured Secured (a) Total Demand notes $ 3,652 $ — $ 3,652 $ 3,622 $ — $ 3,622 Federal Home Loan Bank — 1,850 1,850 — 7,875 7,875 Financial instruments sold under agreements to repurchase — 1,620 1,620 — 1,176 1,176 Other 1,249 (b) — 1,249 — — — Total short-term borrowings $ 4,901 $ 3,470 $ 8,371 $ 3,622 $ 9,051 $ 12,673 (a) Refer to the section below titled Long-term Debt for further details on assets restricted as collateral for payment of the related debt. (b) Balance represents private unsecured committed credit facility and includes debt issuance costs of $1 million as of March 31, 2017 . This debt is scheduled to mature in December 2017.
Schedule of Debt [Table Text Block]	The following table presents the composition of our long-term debt portfolio. March 31, 2017 December 31, 2016 ($ in millions) Unsecured Secured Total Unsecured Secured Total Long-term debt Due within one year $ 2,329 $ 9,048 $ 11,377 $ 4,274 $ 10,279 $ 14,553 Due after one year (a) 14,893 24,492 39,385 15,450 23,810 39,260 Fair value adjustment (b) 308 (9 ) 299 326 (11 ) 315 Total long-term debt (c) $ 17,530 $ 33,531 $ 51,061 $ 20,050 $ 34,078 $ 54,128 (a) Includes $2.6 billion of trust preferred securities at both March 31, 2017, and December 31, 2016. (b) Represents the fair value adjustment associated with the application of hedge accounting on certain of our long-term debt positions. Refer to Note 19 for additional information. (c) Includes advances from the FHLB of Pittsburgh of $6.1 billion at both March 31, 2017, and December 31, 2016
Scheduled Remaining Maturity of Long-term Debt [Table Text Block]	The following table presents the scheduled remaining maturity of long-term debt at March 31, 2017 , assuming no early redemptions will occur. The actual payment of secured debt may vary based on the payment activity of the related pledged assets. ($ in millions) 2017 2018 2019 2020 2021 2022 and thereafter Fair value adjustment Total Unsecured Long-term debt $ 1,811 $ 3,700 $ 1,681 $ 2,236 $ 638 $ 8,460 $ 308 $ 18,834 Original issue discount (69 ) (101 ) (39 ) (39 ) (42 ) (1,014 ) — (1,304 ) Total unsecured 1,742 3,599 1,642 2,197 596 7,446 308 17,530 Secured Long-term debt 7,575 8,534 8,080 5,175 2,558 1,618 (9 ) 33,531 Total long-term debt $ 9,317 $ 12,133 $ 9,722 $ 7,372 $ 3,154 $ 9,064 $ 299 $ 51,061
Pledged assets for the payment of the related secured borrowings and repurchase agreements [Table Text Block]	The following summarizes assets restricted as collateral for the payment of the related debt obligation primarily arising from securitization transactions accounted for as secured borrowings and repurchase agreements. March 31, 2017 December 31, 2016 ($ in millions) Total (a) Ally Bank Total (a) Ally Bank Investment securities (b) $ 3,175 $ 1,978 $ 4,895 $ 4,231 Mortgage assets held-for-investment and lending receivables 10,847 10,847 10,954 10,954 Consumer automotive finance receivables (b) 26,420 4,523 27,846 5,751 Commercial automotive finance receivables 17,901 17,709 19,487 19,280 Investment in operating leases, net 1,412 314 2,040 913 Total assets restricted as collateral (c) (d) $ 59,755 $ 35,371 $ 65,222 $ 41,129 Secured debt $ 37,001 (e) $ 15,120 $ 43,129 (e) $ 22,149 (a) Ally Bank is a component of the total column. (b) A portion of the restricted investment securities and consumer automotive finance receivables are restricted under repurchase agreements. Refer to the section above titled Short-term Borrowings for information on the repurchase agreements. (c) Ally Bank has an advance agreement with the FHLB, and had assets pledged to secure borrowings that were restricted as collateral to the FHLB totaling $16.8 billion and $19.0 billion at March 31, 2017 , and December 31, 2016 , respectively. These assets were composed primarily of consumer mortgage finance receivables and loans and investment securities. Ally Bank has access to the Federal Reserve Bank Discount Window. Ally Bank had assets pledged and restricted as collateral to the Federal Reserve Bank totaling $2.3 billion and $2.4 billion at March 31, 2017 , and December 31, 2016 , respectively. These assets were composed of consumer automotive finance receivables and loans and operating lease assets. Availability under these programs is only for the operations of Ally Bank and cannot be used to fund the operations or liabilities of Ally or its subsidiaries. (d) Excludes restricted cash and cash reserves for securitization trusts recorded within other assets on the Condensed Consolidated Balance Sheet . Refer to Note 12 for additional information. (e) Includes $3.5 billion and $9.1 billion of short-term borrowings at March 31, 2017 , and December 31, 2016 , respectively.
Schedule Of Committed Funding Facilities [Table Text Block]	Committed Funding Facilities Outstanding Unused capacity (a) Total capacity ($ in millions) March 31, 2017 December 31, 2016 March 31, 2017 December 31, 2016 March 31, 2017 December 31, 2016 Bank funding Secured (b) $ 2,050 $ 3,250 $ 350 $ 350 $ 2,400 $ 3,600 Parent funding Secured 12,123 11,550 652 1,975 12,775 13,525 Unsecured 1,250 — — 1,250 1,250 1,250 Total committed facilities $ 15,423 $ 14,800 $ 1,002 $ 3,575 $ 16,425 $ 18,375 (a) Funding from committed secured facilities is available on request in the event excess collateral resides in certain facilities or is available to the extent incremental collateral is available and contributed to the facilities. (b) Excludes off-balance sheet credit facility amounts.

Accrued Expenses and Other Li48

Accrued Expenses and Other Liabilities (Tables)	3 Months Ended
	Mar. 31, 2017
Accounts Payable and Accrued Liabilities [Abstract]
Schedule of Accrued Liabilities [Table Text Block]	The components of accrued expenses and other liabilities were as follows. ( $ in millions ) March 31, 2017 December 31, 2016 Accounts payable $ 851 $ 649 Reserves for insurance losses and loss adjustment expenses 175 149 Employee compensation and benefits 156 232 Fair value of derivative contracts in payable position (a) 81 95 Deferred revenue 47 56 Cash collateral received from counterparties 12 10 Other liabilities 600 546 Total accrued expenses and other liabilities $ 1,922 $ 1,737 (a) For additional information on derivative instruments and hedging activities, refer to Note 19 .

Accumulated Other Comprehensi49

Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following table presents changes, net of tax, in each component of accumulated other comprehensive loss. ($ in millions) Unrealized (losses) gains on investment securities (a) Translation adjustments and net investment hedges (b) Cash flow hedges (b) Defined benefit pension plans Accumulated other comprehensive loss Balance at December 31, 2015 $ (159 ) $ 9 $ 8 $ (89 ) $ (231 ) 2016 net change 142 5 — (1 ) 146 Balance at March 31, 2016 $ (17 ) $ 14 $ 8 $ (90 ) $ (85 ) Balance at December 31, 2016 $ (273 ) $ 14 $ 8 $ (90 ) $ (341 ) 2017 net change 21 — — (1 ) 20 Balance at March 31, 2017 $ (252 ) $ 14 $ 8 $ (91 ) $ (321 ) (a) Represents the after-tax difference between the fair value and amortized cost of our available-for-sale securities portfolio. (b) For additional information on derivative instruments and hedging activities, refer to Note 19 .
Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]	The following tables present the before- and after-tax changes in each component of accumulated other comprehensive loss. Three months ended March 31, 2017 ($ in millions) Before tax Tax effect After tax Investment securities Net unrealized gains arising during the period $ 51 $ (5 ) $ 46 Less: Net realized gains reclassified to income from continuing operations 27 (a) (2 ) (b) 25 Net change 24 (3 ) 21 Translation adjustments Net unrealized gains arising during the period 2 (1 ) 1 Net investment hedges (c) Net unrealized losses arising during the period (2 ) 1 (1 ) Defined benefit pension plans Net unrealized losses arising during the period (1 ) — (1 ) Other comprehensive income $ 23 $ (3 ) $ 20 (a) Includes gains reclassified to other gain on investments, net in our Condensed Consolidated Statement of Comprehensive Income . (b) Includes amounts reclassified to income tax expense from continuing operations in our Condensed Consolidated Statement of Comprehensive Income . (c) For additional information on derivative instruments and hedging activities, refer to Note 19 . Three months ended March 31, 2016 ($ in millions) Before tax Tax effect After tax Investment securities Net unrealized gains arising during the period $ 280 $ (104 ) $ 176 Less: Net realized gains reclassified to income from continuing operations 54 (a) (20 ) (b) 34 Net change 226 (84 ) 142 Translation adjustments Net unrealized gains arising during the period 13 (5 ) 8 Net investment hedges (c) Net unrealized losses arising during the period (6 ) 3 (3 ) Defined benefit pension plans Net unrealized losses arising during the period (1 ) — (1 ) Other comprehensive income $ 232 $ (86 ) $ 146 (a) Includes gains reclassified to other gain on investments, net in our Condensed Consolidated Statement of Comprehensive Income . (b) Includes amounts reclassified to income tax expense from continuing operations in our Condensed Consolidated Statement of Comprehensive Income . (c) For additional information on derivative instruments and hedging activities, refer to Note 19 .

Earnings per Common Share (Tabl

Earnings per Common Share (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table presents the calculation of basic and diluted earnings per common share. Three months ended March 31, ( $ in millions, except per share data; shares in thousands ) (a) 2017 2016 Net income from continuing operations $ 213 $ 247 Preferred stock dividends — (15 ) Net income from continuing operations attributable to common shareholders 213 232 Income from discontinued operations, net of tax 1 3 Net income attributable to common shareholders $ 214 $ 235 Basic weighted-average common shares outstanding (b) 465,961 484,233 Diluted weighted-average common shares outstanding (b) 466,829 484,654 Basic earnings per common share Net income from continuing operations $ 0.46 $ 0.48 Income from discontinued operations, net of tax — 0.01 Net income $ 0.46 $ 0.49 Diluted earnings per common share Net income from continuing operations $ 0.46 $ 0.48 Income from discontinued operations, net of tax — 0.01 Net income $ 0.46 $ 0.49 (a) Figures in the table may not recalculate exactly due to rounding. Earnings per share is calculated based on unrounded numbers. (b) Includes shares related to share-based compensation that vested but were not yet issued for the three months ended March 31, 2017 , and 2016 , respectively.

Regulatory Capital and Other 51

Regulatory Capital and Other Regulatory Matters (Tables)	3 Months Ended
	Mar. 31, 2017
Regulatory Capital Requirements [Abstract]
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block]	The following table summarizes our capital ratios under the U.S. Basel III capital framework. March 31, 2017 December 31, 2016 Required Well-capitalized ( $ in millions ) Amount Ratio Amount Ratio Capital ratios Common Equity Tier 1 (to risk-weighted assets) Ally Financial Inc. $ 12,923 9.40 % $ 12,978 9.37 % 4.50 % (a) Ally Bank 18,562 17.74 17,888 16.70 4.50 6.50 % Tier 1 (to risk-weighted assets) Ally Financial Inc. $ 15,245 11.09 % $ 15,147 10.93 % 6.00 % 6.00 % Ally Bank 18,562 17.74 17,888 16.70 6.00 8.00 Total (to risk-weighted assets) Ally Financial Inc. $ 17,459 12.70 % $ 17,419 12.57 % 8.00 % 10.00 % Ally Bank 19,167 18.32 18,458 17.24 8.00 10.00 Tier 1 leverage (to adjusted quarterly average assets) (b) Ally Financial Inc. $ 15,245 9.51 % $ 15,147 9.54 % 4.00 % (a) Ally Bank 18,562 15.38 17,888 15.21 15.00 (c) 5.00 % (a) Currently, there is no ratio component for determining whether a BHC is "well-capitalized." (b) Federal regulatory reporting guidelines require the calculation of adjusted quarterly average assets using a daily average methodology. (c) Ally Bank has committed to the FRB to maintain a Tier 1 leverage ratio of at least 15% .

Derivative Instruments and He52

Derivative Instruments and Hedging Activities (Tables)	3 Months Ended
	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value Amounts of Derivative Instruments Reported On Our Condensed Consolidated Balance Sheet [Table Text Block]	The following table summarizes the fair value amounts of derivative instruments reported on our Condensed Consolidated Balance Sheet . The fair value amounts are presented on a gross basis, are segregated by derivatives that are designated and qualifying as hedging instruments or those that are not, and are further segregated by type of contract within those two categories. Notional amounts are reference amounts from which contractual obligations are derived and are not recorded on the balance sheet. In our view, derivative notional is not an accurate measure of our derivative exposure when viewed in isolation from other factors, such as market rate fluctuations and counterparty credit risk. March 31, 2017 December 31, 2016 Derivative contracts in a Notional Derivative contracts in a Notional ($ in millions) receivable payable receivable payable Derivatives designated as accounting hedges Interest rate contracts Swaps (c) (d) (e) $ 18 $ 17 $ 3,939 $ 19 $ 21 $ 4,731 Foreign exchange contracts Forwards — 1 150 1 — 171 Total derivatives designated as accounting hedges 18 18 4,089 20 21 4,902 Derivatives not designated as accounting hedges Interest rate contracts Swaps — — 43 — — 137 Futures and forwards — — 25 — — — Written options — 62 13,432 — 73 14,518 Purchased options 62 — 13,407 73 — 14,517 Total interest rate risk 62 62 26,907 73 73 29,172 Foreign exchange contracts Futures and forwards — 1 94 1 — 92 Total foreign exchange risk — 1 94 1 — 92 Equity contracts Written options — — — — 1 — Purchased options — — — 1 — — Total equity risk — — — 1 1 — Total derivatives not designated as accounting hedges 62 63 27,001 75 74 29,264 Total derivatives $ 80 $ 81 $ 31,090 $ 95 $ 95 $ 34,166 (a) Derivative contracts in a receivable position are classified as other assets on the Condensed Consolidated Balance Sheet , and include accrued interest of $3 million and $7 million at March 31, 2017 , and December 31, 2016 , respectively. (b) Derivative contracts in a liability position are classified as accrued expenses and other liabilities on the Condensed Consolidated Balance Sheet , and include accrued interest of $0 million and $1 million at March 31, 2017 , and December 31, 2016 , respectively. (c) Includes fair value hedges consisting of receive-fixed swaps on fixed-rate unsecured debt obligations with $11 million and $8 million in a receivable position, $18 million and $14 million in a payable position, and a $2.6 billion and $1.7 billion notional amount at March 31, 2017 , and December 31, 2016 , respectively. The hedge notional amount of $2.6 billion at March 31, 2017 , is associated with debt maturing in approximately five or more years. (d) Includes fair value hedges consisting of receive-fixed swaps on fixed-rate secured debt obligations (FHLB advances) with $0 million and $0 million in a receivable position, $0 million and $7 million in a payable position, and a $0 million and $240 million notional amount at March 31, 2017 , and December 31, 2016 , respectively. (e) Other fair value hedges include pay-fixed swaps on portfolios of held-for-investment automotive loan assets with $7 million and $10 million in a receivable position, $0 million and $1 million in a payable position, and a $1.4 billion and $2.8 billion notional amount at March 31, 2017 , and December 31, 2016 , respectively.
Gains and Losses On Derivative Instruments Reported in Statement of Comprehensive Income [Table Text Block]	The following table summarizes the location and amounts of gains and losses on derivative instruments reported in our Condensed Consolidated Statement of Comprehensive Income . Three months ended March 31, ( $ in millions ) 2017 2016 Derivatives qualifying for hedge accounting Gain (loss) recognized in earnings on derivatives Interest rate contracts Interest and fees on finance receivables and loans (a) $ 2 $ (28 ) Interest on long-term debt (b) (c) 4 191 (Loss) gain recognized in earnings on hedged items Interest rate contracts Interest and fees on finance receivables and loans (d) (4 ) 28 Interest on long-term debt (e) (f) (3 ) (196 ) Total derivatives qualifying for hedge accounting (1 ) (5 ) Derivatives not designated as accounting hedges (Loss) gain recognized in earnings on derivatives Interest rate contracts Other income, net of losses (2 ) 2 Total interest rate contracts (2 ) 2 Foreign exchange contracts (g) Interest on long-term debt — (1 ) Other income, net of losses (1 ) (4 ) Total foreign exchange contracts (1 ) (5 ) Equity contracts Compensation and benefits expense — (1 ) Total equity contracts — (1 ) Loss recognized in earnings on derivatives $ (4 ) $ (9 ) (a) Amounts exclude losses related to interest for qualifying accounting hedges of retail automotive loans held-for-investment, which are primarily offset by the fixed coupon payments of the loans. The losses were $1 million and $7 million for the three months ended March 31, 2017 , and 2016 , respectively. (b) Amounts exclude gains related to interest for qualifying accounting hedges of unsecured debt, which are primarily offset by the fixed coupon payment on the long-term debt. The gains were $5 million and $16 million for the three months ended March 31, 2017 , and 2016 , respectively. (c) Amounts exclude gains related to interest for qualifying accounting hedges of secured debt (FHLB advances), which are primarily offset by the fixed coupon payment on the long-term debt. The gains were $0 million and $1 million for the three months ended March 31, 2017 , and 2016 , respectively. (d) Amounts exclude losses related to amortization of deferred loan basis adjustments on the de-designated hedged item of $5 million for both the three months ended March 31, 2017 , and 2016 . (e) Amounts exclude gains related to amortization of deferred debt basis adjustments on the de-designated hedged item of $20 million and $18 million for the three months ended March 31, 2017 , and 2016 , respectively. (f) Amounts exclude losses related to amortization of deferred debt basis adjustments (FHLB advances) on the de-designated hedge item of $1 million and $0 million for the three months ended March 31, 2017, and 2016, respectively. (g) Amounts exclude gains and losses related to the revaluation of the related foreign-denominated debt or receivable. Gains of $1 million and $4 million were recognized for the three months ended March 31, 2017 , and 2016 , respectively.
Derivative Instruments Used in Cash Flow and Net Investment Hedge Accounting Relationships [Table Text Block]	Losses of $2 million and $6 million were recognized in other comprehensive income for the three months ended March 31, 2017, and 2016, respectively. These amounts represent the effective portion of net investment hedges. There are offsetting amounts recognized in accumulated other comprehensive loss related to the revaluation of the related net investment in foreign operations, including the tax impacts of the hedge and related net investment, as disclosed separately in Note 16 . There were gains of $3 million and $11 million for the three months ended March 31, 2017 , and 2016, respectively.

Fair Value (Tables)

Fair Value (Tables)	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements - Recurring Basis [Table Text Block]	The following tables display the assets and liabilities measured at fair value on a recurring basis including financial instruments elected for the fair value option. We often economically hedge the fair value change of our assets or liabilities with derivatives and other financial instruments. The tables below display the hedges separately from the hedged items; therefore, they do not directly display the impact of our risk management activities. Recurring fair value measurements March 31, 2017 ($ in millions) Level 1 Level 2 Level 3 Total Assets Investment securities Available-for-sale securities Debt securities U.S. Treasury $ 2,225 $ — $ — $ 2,225 U.S. States and political subdivisions — 795 — 795 Foreign government 9 137 — 146 Agency mortgage-backed residential — 11,862 — 11,862 Mortgage-backed residential — 1,996 — 1,996 Mortgage-backed commercial — 534 — 534 Asset-backed — 1,051 — 1,051 Corporate debt — 1,255 — 1,255 Total debt securities 2,234 17,630 — 19,864 Equity securities (a) 444 — — 444 Total available-for-sale securities 2,678 17,630 — 20,308 Mortgage loans held-for-sale — — 1 1 Interests retained in financial asset sales — — 31 31 Derivative contracts in a receivable position (b) Interest rate — 80 — 80 Total derivative contracts in a receivable position — 80 — 80 Total assets $ 2,678 $ 17,710 $ 32 $ 20,420 Liabilities Accrued expenses and other liabilities Derivative contracts in a payable position (b) Interest rate $ — $ (80 ) $ — $ (80 ) Foreign currency — (1 ) — (1 ) Total derivative contracts in a payable position — (81 ) — (81 ) Total liabilities $ — $ (81 ) $ — $ (81 ) (a) Our investment in any one industry did not exceed 16% . (b) For additional information on derivative instruments and hedging activities, refer to Note 19 . Recurring fair value measurements December 31, 2016 ($ in millions) Level 1 Level 2 Level 3 Total Assets Investment securities Available-for-sale securities Debt securities U.S. Treasury $ 1,620 $ — $ — $ 1,620 U.S. States and political subdivisions — 782 — 782 Foreign government 11 151 — 162 Agency mortgage-backed residential — 10,290 — 10,290 Mortgage-backed residential — 2,097 — 2,097 Mortgage-backed commercial — 537 — 537 Asset-backed — 1,400 — 1,400 Corporate debt — 1,443 — 1,443 Total debt securities 1,631 16,700 — 18,331 Equity securities (a) 595 — — 595 Total available-for-sale securities 2,226 16,700 — 18,926 Other assets Interests retained in financial asset sales — — 29 29 Derivative contracts in a receivable position (b) Interest rate — 92 — 92 Foreign currency — 2 — 2 Other 1 — — 1 Total derivative contracts in a receivable position 1 94 — 95 Total assets $ 2,227 $ 16,794 $ 29 $ 19,050 Liabilities Accrued expenses and other liabilities Derivative contracts in a payable position (b) Interest rate $ — $ (94 ) $ — $ (94 ) Other (1 ) — — (1 ) Total derivative contracts in a payable position (1 ) (94 ) — (95 ) Total liabilities $ (1 ) $ (94 ) $ — $ (95 ) (a) Our investment in any one industry did not exceed 14% . (b) For additional information on derivative instruments and hedging activities, refer to Note 19 . The following tables present the reconciliation for all Level 3 assets and liabilities measured at fair value on a recurring basis. We often economically hedge the fair value change of our assets or liabilities with derivatives and other financial instruments. The Level 3 items presented below may be hedged by derivatives and other financial instruments that are classified as Level 1 or Level 2. Thus, the following tables do not fully reflect the impact of our risk management activities.
Fair Value Measurements - Reconciliation of Level 3 Assets and Liabilities [Table Text Block]	The following tables present the reconciliation for all Level 3 assets and liabilities measured at fair value on a recurring basis. We often economically hedge the fair value change of our assets or liabilities with derivatives and other financial instruments. The Level 3 items presented below may be hedged by derivatives and other financial instruments that are classified as Level 1 or Level 2. Thus, the following tables do not fully reflect the impact of our risk management activities. Level 3 recurring fair value measurements Net realized/unrealized Fair value at Net unrealized gains included in earnings ($ in millions) Fair value at Jan. 1, 2017 included in earnings included in OCI Purchases Sales Issuances Settlements Assets Mortgage loans held-for-sale $ — $ — $ — $ 3 $ (2 ) $ — $ — $ 1 $ — Other assets Interests retained in financial asset sales 29 — — — 4 — (2 ) 31 — Total assets $ 29 $ — $ — $ 3 $ 2 $ — $ (2 ) $ 32 $ — Level 3 recurring fair value measurements Fair value at Jan. 1, 2016 Net realized/unrealized Purchases Sales Issuances Settlements Fair value at Net unrealized gains included in earnings ($ in millions) included in earnings included in OCI Assets Other assets Interests retained in financial asset sales $ 40 $ 2 (a) $ — $ — $ 4 $ — $ (15 ) $ 31 $ — Total assets $ 40 $ 2 $ — $ — $ 4 $ — $ (15 ) $ 31 $ — (a) Reported as other income, net of losses, in the Condensed Consolidated Statement of Comprehensive Income .
Fair Value Measurements - Nonrecurring Basis [Table Text Block]	The following tables display the assets and liabilities measured at fair value on a nonrecurring basis. Nonrecurring Lower-of-cost or Total gain (loss) included in earnings for the three months ended March 31, 2017 ($ in millions) Level 1 Level 2 Level 3 Total Assets Commercial finance receivables and loans, net (a) Commercial and industrial Automotive $ — $ — $ 29 $ 29 $ (3 ) n/m (b) Other — — 61 61 (21 ) n/m (b) Total commercial finance receivables and loans, net — — 90 90 (24 ) n/m (b) Other assets Repossessed and foreclosed assets (c) — — 15 15 (2 ) n/m (b) Other — — 4 4 — n/m (b) Total assets $ — $ — $ 109 $ 109 $ (26 ) n/m n/m = not meaningful (a) Represents the portion of the portfolio specifically impaired during 2017 . The related valuation allowance represents the cumulative adjustment to fair value of those specific receivables. (b) We consider the applicable valuation or loan loss allowance to be the most relevant indicator of the impact on earnings caused by the fair value measurement. Accordingly, the table above excludes total gains and losses included in earnings for these items. The carrying values are inclusive of the respective valuation or loan loss allowance. (c) The allowance provided for repossessed and foreclosed assets represents any cumulative valuation adjustment recognized to adjust the assets to fair value. Nonrecurring Lower-of-cost or Total gain (loss) included in earnings for the three months ended March 31, 2016 ($ in millions) Level 1 Level 2 Level 3 Total Assets Loans held-for-sale, net $ — $ — $ 39 $ 39 $ — n/m (a) Commercial finance receivables and loans, net (b) Commercial and industrial Automotive — — 17 17 (3 ) n/m (a) Other — — 28 28 (15 ) n/m (a) Total commercial finance receivables and loans, net — — 45 45 (18 ) n/m (a) Other assets Repossessed and foreclosed assets (c) — — 12 12 (3 ) n/m (a) Other — — 6 6 — n/m (a) Total assets $ — $ — $ 102 $ 102 $ (21 ) n/m n/m = not meaningful (a) We consider the applicable valuation or loan loss allowance to be the most relevant indicator of the impact on earnings caused by the fair value measurement. Accordingly, the table above excludes total gains and losses included in earnings for these items. The carrying values are inclusive of the respective valuation or loan loss allowance. (b) Represents the portion of the portfolio specifically impaired during 2016 . The related valuation allowance represents the cumulative adjustment to fair value of those specific receivables. (c) The allowance provided for repossessed and foreclosed assets represents any cumulative valuation adjustment recognized to adjust the assets to fair value.
Fair Value of Financial Intruments [Table Text Block]	The following table presents the carrying and estimated fair value of financial instruments, except for those recorded at fair value on a recurring basis presented in the previous section of this note titled Recurring Fair Value. When possible, we use quoted market prices to determine fair value. Where quoted market prices are not available, the fair value is internally derived based on appropriate valuation methodologies with respect to the amount and timing of future cash flows and estimated discount rates. However, considerable judgment is required in interpreting current market data to develop the market assumptions and inputs necessary to estimate fair value. As such, the actual amount received to sell an asset or the amount paid to settle a liability could differ from our estimates. Fair value information presented herein was based on information available at March 31, 2017 , and December 31, 2016 . Estimated fair value ($ in millions) Carrying value Level 1 Level 2 Level 3 Total March 31, 2017 Financial assets Held-to-maturity securities $ 1,104 $ — $ 1,063 $ — $ 1,063 Finance receivables and loans, net 117,847 — — 119,420 119,420 Nonmarketable equity investments 833 — 795 59 854 Financial liabilities Deposit liabilities $ 84,486 $ — $ — $ 82,715 $ 82,715 Short-term borrowings 8,371 — — 8,372 8,372 Long-term debt 51,061 — 19,604 33,511 53,115 December 31, 2016 Financial assets Held-to-maturity securities $ 839 $ — $ 789 $ — $ 789 Finance receivables and loans, net 117,800 — — 118,750 118,750 Nonmarketable equity investments 1,046 — 1,012 55 1,067 Financial liabilities Deposit liabilities $ 79,022 $ — $ — $ 78,469 $ 78,469 Short-term borrowings 12,673 — — 12,675 12,675 Long-term debt 54,128 — 22,036 34,084 56,120 The following describes the methodologies and assumptions used to determine fair value for the significant classes of financial instruments. In addition to the valuation methods discussed below, we also followed guidelines for determining whether a market was not active and a transaction was not distressed. We assumed the price that would be received in an orderly transaction (including a market-based return) and not in forced liquidation or distressed sale.

Offsetting Assets and Liabili54

Offsetting Assets and Liabilities Offsetting Assets and Liabilities (Assets) (Tables)	3 Months Ended
	Mar. 31, 2017
Offsetting Assets and Liabilities [Abstract]
Offsetting Assets [Table Text Block]	The composition of offsetting derivative instruments, financial assets, and financial liabilities was as follows. Gross amounts of recognized assets/(liabilities) Gross amounts offset in the Condensed Consolidated Balance Sheet Net amounts of assets/(liabilities) Gross amounts not offset in the Condensed Consolidated Balance Sheet March 31, 2017 ($ in millions) Financial instruments Collateral Net amount Assets Derivative assets in net asset positions $ 78 $ — $ 78 $ (5 ) $ (8 ) $ 65 Derivative assets in net liability positions 2 — 2 (2 ) — — Total assets (d) $ 80 $ — $ 80 $ (7 ) $ (8 ) $ 65 Liabilities Derivative liabilities in net liability positions $ (76 ) $ — $ (76 ) $ 2 $ 14 $ (60 ) Derivative liabilities in net asset positions (5 ) — (5 ) 5 — — Total derivative liabilities (d) (81 ) — (81 ) 7 14 (60 ) Securities sold under agreements to repurchase (e) (1,146 ) — (1,146 ) — 1,146 — Total liabilities $ (1,227 ) $ — $ (1,227 ) $ 7 $ 1,160 $ (60 ) (a) Financial collateral received/pledged shown as a balance based on the sum of all net asset and liability positions between Ally and each individual derivative counterparty. (b) Amounts disclosed are limited to the financial asset or liability balance and, accordingly, exclude excess collateral received or pledged and noncash collateral received. $6 million of noncash derivative collateral pledged to us was excluded at March 31, 2017 . We do not record such collateral received on our Condensed Consolidated Balance Sheet unless certain conditions are met. (c) Certain agreements grant us the right to sell or pledge the noncash assets we receive as collateral. Noncash collateral pledged to us where the agreement grants us the right to sell or pledge the underlying assets had a fair value of $6 million at March 31, 2017 . We have not sold or pledged any of the noncash collateral received under these agreements as of March 31, 2017 . (d) For additional information on derivative instruments and hedging activities, refer to Note 19 . (e) For additional information on securities sold under agreements to repurchase, refer to Note 14 . Gross amounts of recognized assets/(liabilities) Gross amounts offset in the Condensed Consolidated Balance Sheet Net amounts of assets/(liabilities) Gross amounts not offset in the Condensed Consolidated Balance Sheet December 31, 2016 ( $ in millions ) Financial instruments Collateral Net amount Assets Derivative assets in net asset positions $ 87 $ — $ 87 $ (4 ) $ (9 ) $ 74 Derivative assets in net liability positions 8 — 8 (8 ) — — Total assets (d) $ 95 $ — $ 95 $ (12 ) $ (9 ) $ 74 Liabilities Derivative liabilities in net liability positions $ (91 ) $ — $ (91 ) $ 8 $ 13 $ (70 ) Derivative liabilities in net asset positions (4 ) — (4 ) 4 — — Total derivative liabilities (d) (95 ) — (95 ) 12 13 (70 ) Securities sold under agreements to repurchase (e) (676 ) — (676 ) — 676 — Total liabilities $ (771 ) $ — $ (771 ) $ 12 $ 689 $ (70 ) (a) Financial collateral received/pledged shown as a balance based on the sum of all net asset and liability positions between Ally and each individual derivative counterparty. (b) Amounts disclosed are limited to the financial asset or liability balance and, accordingly, exclude excess collateral received or pledged and noncash collateral received. $6 million of noncash derivative collateral pledged to us was excluded at December 31, 2016. We do not record such collateral received on our Condensed Consolidated Balance Sheet unless certain conditions are met. (c) Certain agreements grant us the right to sell or pledge the noncash assets we receive as collateral. Noncash collateral pledged to us where the agreement grants us the right to sell or pledge the underlying assets had a fair value of $6 million at December 31, 2016. We have not sold or pledged any of the noncash collateral received under these agreements as of December 31, 2016. (d) For additional information on derivative instruments and hedging activities, refer to Note 19 . (e) For additional information on securities sold under agreements to repurchase, refer to Note 14 .

Offsetting Assets and Liabili55

Offsetting Assets and Liabilities Offsetting Assets and Liabilities (Liabilities) (Tables)	3 Months Ended
	Mar. 31, 2017
Offsetting Liabilities [Abstract]
Offsetting Liabilities [Table Text Block]	The composition of offsetting derivative instruments, financial assets, and financial liabilities was as follows. Gross amounts of recognized assets/(liabilities) Gross amounts offset in the Condensed Consolidated Balance Sheet Net amounts of assets/(liabilities) Gross amounts not offset in the Condensed Consolidated Balance Sheet March 31, 2017 ($ in millions) Financial instruments Collateral Net amount Assets Derivative assets in net asset positions $ 78 $ — $ 78 $ (5 ) $ (8 ) $ 65 Derivative assets in net liability positions 2 — 2 (2 ) — — Total assets (d) $ 80 $ — $ 80 $ (7 ) $ (8 ) $ 65 Liabilities Derivative liabilities in net liability positions $ (76 ) $ — $ (76 ) $ 2 $ 14 $ (60 ) Derivative liabilities in net asset positions (5 ) — (5 ) 5 — — Total derivative liabilities (d) (81 ) — (81 ) 7 14 (60 ) Securities sold under agreements to repurchase (e) (1,146 ) — (1,146 ) — 1,146 — Total liabilities $ (1,227 ) $ — $ (1,227 ) $ 7 $ 1,160 $ (60 ) (a) Financial collateral received/pledged shown as a balance based on the sum of all net asset and liability positions between Ally and each individual derivative counterparty. (b) Amounts disclosed are limited to the financial asset or liability balance and, accordingly, exclude excess collateral received or pledged and noncash collateral received. $6 million of noncash derivative collateral pledged to us was excluded at March 31, 2017 . We do not record such collateral received on our Condensed Consolidated Balance Sheet unless certain conditions are met. (c) Certain agreements grant us the right to sell or pledge the noncash assets we receive as collateral. Noncash collateral pledged to us where the agreement grants us the right to sell or pledge the underlying assets had a fair value of $6 million at March 31, 2017 . We have not sold or pledged any of the noncash collateral received under these agreements as of March 31, 2017 . (d) For additional information on derivative instruments and hedging activities, refer to Note 19 . (e) For additional information on securities sold under agreements to repurchase, refer to Note 14 . Gross amounts of recognized assets/(liabilities) Gross amounts offset in the Condensed Consolidated Balance Sheet Net amounts of assets/(liabilities) Gross amounts not offset in the Condensed Consolidated Balance Sheet December 31, 2016 ( $ in millions ) Financial instruments Collateral Net amount Assets Derivative assets in net asset positions $ 87 $ — $ 87 $ (4 ) $ (9 ) $ 74 Derivative assets in net liability positions 8 — 8 (8 ) — — Total assets (d) $ 95 $ — $ 95 $ (12 ) $ (9 ) $ 74 Liabilities Derivative liabilities in net liability positions $ (91 ) $ — $ (91 ) $ 8 $ 13 $ (70 ) Derivative liabilities in net asset positions (4 ) — (4 ) 4 — — Total derivative liabilities (d) (95 ) — (95 ) 12 13 (70 ) Securities sold under agreements to repurchase (e) (676 ) — (676 ) — 676 — Total liabilities $ (771 ) $ — $ (771 ) $ 12 $ 689 $ (70 ) (a) Financial collateral received/pledged shown as a balance based on the sum of all net asset and liability positions between Ally and each individual derivative counterparty. (b) Amounts disclosed are limited to the financial asset or liability balance and, accordingly, exclude excess collateral received or pledged and noncash collateral received. $6 million of noncash derivative collateral pledged to us was excluded at December 31, 2016. We do not record such collateral received on our Condensed Consolidated Balance Sheet unless certain conditions are met. (c) Certain agreements grant us the right to sell or pledge the noncash assets we receive as collateral. Noncash collateral pledged to us where the agreement grants us the right to sell or pledge the underlying assets had a fair value of $6 million at December 31, 2016. We have not sold or pledged any of the noncash collateral received under these agreements as of December 31, 2016. (d) For additional information on derivative instruments and hedging activities, refer to Note 19 . (e) For additional information on securities sold under agreements to repurchase, refer to Note 14 .

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Financial information for our reportable operating segments is summarized as follows. Three months ended March 31, ($ in millions) Automotive Finance operations Insurance operations Mortgage Finance operations Corporate Finance operations Corporate and Other Consolidated (a) 2017 Net financing revenue and other interest income $ 892 $ 15 $ 34 $ 34 $ 4 $ 979 Other revenue 101 264 — 18 13 396 Total net revenue 993 279 34 52 17 1,375 Provision for loan losses 268 — 1 6 (4 ) 271 Total noninterest expense 437 239 24 21 57 778 Income (loss) from continuing operations before income tax expense $ 288 $ 40 $ 9 $ 25 $ (36 ) $ 326 Total assets $ 115,154 $ 7,230 $ 8,362 $ 3,438 $ 27,917 $ 162,101 2016 Net financing revenue and other interest income (loss) $ 896 $ 14 $ 20 $ 28 $ (7 ) $ 951 Other revenue 77 254 — 6 39 376 Total net revenue 973 268 20 34 32 1,327 Provision for loan losses 209 — 3 6 2 220 Total noninterest expense 427 218 15 17 33 710 Income (loss) from continuing operations before income tax expense $ 337 $ 50 $ 2 $ 11 $ (3 ) $ 397 Total assets $ 112,289 $ 7,194 $ 7,493 $ 2,839 $ 26,690 $ 156,505 (a) Net financing revenue and other interest income after the provision for loan losses totaled $708 million and $731 million for the three months ended March 31, 2017 , and 2016 , respectively.

Parent and Guarantor Condense57

Parent and Guarantor Condensed Consolidating Financial Statements (Tables)	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Condensed Income Statement [Table Text Block]	Condensed Consolidating Statements of Comprehensive Income Three months ended March 31, 2017 ($ in millions) Parent Guarantors Nonguarantors Consolidating adjustments Ally consolidated Financing (loss) revenue and other interest income Interest and fees on finance receivables and loans $ (35 ) $ — $ 1,403 $ — $ 1,368 Interest and fees on finance receivables and loans — intercompany 4 — 3 (7 ) — Interest and dividends on investment securities and other earning assets — — 135 (1 ) 134 Interest on cash and cash equivalents 2 — 3 — 5 Interest-bearing cash — intercompany — — 1 (1 ) — Operating leases 3 — 540 — 543 Total financing (loss) revenue and other interest income (26 ) — 2,085 (9 ) 2,050 Interest expense Interest on deposits 1 — 230 — 231 Interest on short-term borrowings 17 — 10 — 27 Interest on long-term debt 281 — 143 — 424 Interest on intercompany debt 4 — 4 (8 ) — Total interest expense 303 — 387 (8 ) 682 Net depreciation expense on operating lease assets 2 — 387 — 389 Net financing revenue (331 ) — 1,311 (1 ) 979 Cash dividends from subsidiaries Nonbank subsidiaries 41 — — (41 ) — Other revenue Insurance premiums and service revenue earned — — 241 — 241 (Loss) gain on mortgage and automotive loans, net (2 ) — 16 — 14 Loss on extinguishment of debt — — (1 ) — (1 ) Other gain on investments, net — — 27 — 27 Other income, net of losses 268 — 224 (377 ) 115 Total other revenue 266 — 507 (377 ) 396 Total net revenue (24 ) — 1,818 (419 ) 1,375 Provision for loan losses 107 — 164 — 271 Noninterest expense Compensation and benefits expense 122 — 163 — 285 Insurance losses and loss adjustment expenses — — 88 — 88 Other operating expenses 288 — 494 (377 ) 405 Total noninterest expense 410 — 745 (377 ) 778 (Loss) income from continuing operations before income tax (benefit) expense and undistributed income (loss) of subsidiaries (541 ) — 909 (42 ) 326 Income tax (benefit) expense from continuing operations (134 ) — 247 — 113 Net (loss) income from continuing operations (407 ) — 662 (42 ) 213 Income (loss) from discontinued operations, net of tax 2 — (1 ) — 1 Undistributed income of subsidiaries Bank subsidiary 389 389 — (778 ) — Nonbank subsidiaries 230 — — (230 ) — Net income 214 389 661 (1,050 ) 214 Other comprehensive income, net of tax 20 5 19 (24 ) 20 Comprehensive income $ 234 $ 394 $ 680 $ (1,074 ) $ 234 Three months ended March 31, 2016 ($ in millions) Parent Guarantors Nonguarantors Consolidating adjustments Ally consolidated Financing (loss) revenue and other interest income Interest and fees on finance receivables and loans $ (38 ) $ — $ 1,273 $ — $ 1,235 Interest and fees on finance receivables and loans — intercompany 3 — 2 (5 ) — Interest and dividends on investment securities and other earning assets — — 102 — 102 Interest on cash and cash equivalents 1 — 2 — 3 Interest-bearing cash — intercompany — — 2 (2 ) — Operating leases 5 — 764 — 769 Total financing (loss) revenue and other interest income (29 ) — 2,145 (7 ) 2,109 Interest expense Interest on deposits 2 — 191 — 193 Interest on short-term borrowings 10 — 3 — 13 Interest on long-term debt 289 — 153 — 442 Interest on intercompany debt 4 — 3 (7 ) — Total interest expense 305 — 350 (7 ) 648 Net depreciation expense on operating lease assets 4 — 506 — 510 Net financing revenue (338 ) — 1,289 — 951 Cash dividends from subsidiaries Nonbank subsidiaries 482 — — (482 ) — Other revenue Insurance premiums and service revenue earned — — 230 — 230 (Loss) gain on mortgage and automotive loans, net (3 ) — 4 — 1 Loss on extinguishment of debt (2 ) — (2 ) — (4 ) Other gain on investments, net — — 54 — 54 Other income, net of losses 374 — 217 (496 ) 95 Total other revenue 369 — 503 (496 ) 376 Total net revenue 513 — 1,792 (978 ) 1,327 Provision for loan losses 60 — 160 — 220 Noninterest expense Compensation and benefits expense 147 — 105 — 252 Insurance losses and loss adjustment expenses — — 73 — 73 Other operating expenses 340 — 542 (497 ) 385 Total noninterest expense 487 — 720 (497 ) 710 (Loss) income from continuing operations before income tax (benefit) expense and undistributed income (loss) of subsidiaries (34 ) — 912 (481 ) 397 Income tax (benefit) expense from continuing operations (43 ) — 193 — 150 Net (loss) income from continuing operations 9 — 719 (481 ) 247 Income (loss) from discontinued operations, net of tax 6 — (3 ) — 3 Undistributed income (loss) of subsidiaries Bank subsidiary 270 270 — (540 ) — Nonbank subsidiaries (35 ) — — 35 — Net income 250 270 716 (986 ) 250 Other comprehensive income, net of tax 146 84 151 (235 ) 146 Comprehensive income $ 396 $ 354 $ 867 $ (1,221 ) $ 396
Condensed Balance Sheet [Table Text Block]	Condensed Consolidating Balance Sheet March 31, 2017 ($ in millions) Parent (a) Guarantors Nonguarantors (a) Consolidating adjustments Ally consolidated Assets Cash and cash equivalents Noninterest-bearing $ 690 $ — $ 823 $ — $ 1,513 Interest-bearing 800 — 1,989 — 2,789 Interest-bearing — intercompany — — 641 (641 ) — Total cash and cash equivalents 1,490 — 3,453 (641 ) 4,302 Available-for-sale securities 6 — 20,308 (6 ) 20,308 Held-to-maturity securities — — 1,155 (51 ) 1,104 Loans held-for-sale, net — — 1 — 1 Finance receivables and loans, net Finance receivables and loans, net 4,864 — 114,138 — 119,002 Intercompany loans to Bank subsidiary 425 — — (425 ) — Nonbank subsidiaries 1,376 — 456 (1,832 ) — Allowance for loan losses (121 ) — (1,034 ) — (1,155 ) Total finance receivables and loans, net 6,544 — 113,560 (2,257 ) 117,847 Investment in operating leases, net 35 — 10,426 — 10,461 Intercompany receivables from Bank subsidiary 32 — — (32 ) — Nonbank subsidiaries 46 — 255 (301 ) — Investment in subsidiaries Bank subsidiary 18,405 18,405 — (36,810 ) — Nonbank subsidiaries 9,680 — — (9,680 ) — Premiums receivable and other insurance assets — — 1,974 (30 ) 1,944 Other assets 4,275 — 4,764 (2,905 ) 6,134 Total assets $ 40,513 $ 18,405 $ 155,896 $ (52,713 ) $ 162,101 Liabilities Deposit liabilities Noninterest-bearing $ — $ — $ 102 $ — $ 102 Interest-bearing 85 — 84,299 — 84,384 Total deposit liabilities 85 — 84,401 — 84,486 Short-term borrowings 4,901 — 3,470 — 8,371 Long-term debt 20,156 — 30,905 — 51,061 Intercompany debt to Bank subsidiary 51 — — (51 ) — Nonbank subsidiaries 1,097 — 1,807 (2,904 ) — Intercompany payables to Bank subsidiary 127 — — (127 ) — Nonbank subsidiaries 180 — 57 (237 ) — Interest payable 231 — 151 — 382 Unearned insurance premiums and service revenue — — 2,514 — 2,514 Accrued expenses and other liabilities 320 — 4,506 (2,904 ) 1,922 Total liabilities 27,148 — 127,811 (6,223 ) 148,736 Total equity 13,365 18,405 28,085 (46,490 ) 13,365 Total liabilities and equity $ 40,513 $ 18,405 $ 155,896 $ (52,713 ) $ 162,101 (a) Amounts presented are based upon the legal transfer of the underlying assets to VIEs in order to reflect legal ownership. December 31, 2016 ($ in millions) Parent (a) Guarantors Nonguarantors (a) Consolidating adjustments Ally consolidated Assets Cash and cash equivalents Noninterest-bearing $ 720 $ — $ 827 $ — $ 1,547 Interest-bearing 100 — 4,287 — 4,387 Interest-bearing — intercompany — — 401 (401 ) — Total cash and cash equivalents 820 — 5,515 (401 ) 5,934 Trading securities — — 82 (82 ) — Available-for-sale securities — — 19,253 (327 ) 18,926 Held-to-maturity securities — — 839 — 839 Finance receivables and loans, net Finance receivables and loans, net 4,705 — 114,239 — 118,944 Intercompany loans to Bank subsidiary 1,125 — — (1,125 ) — Nonbank subsidiaries 1,779 — 626 (2,405 ) — Allowance for loan losses (115 ) — (1,029 ) — (1,144 ) Total finance receivables and loans, net 7,494 — 113,836 (3,530 ) 117,800 Investment in operating leases, net 42 — 11,428 — 11,470 Intercompany receivables from Bank subsidiary 299 — — (299 ) — Nonbank subsidiaries 107 — 67 (174 ) — Investment in subsidiaries Bank subsidiary 17,727 17,727 — (35,454 ) — Nonbank subsidiaries 10,318 — — (10,318 ) — Premiums receivable and other insurance assets — — 1,936 (31 ) 1,905 Other assets 4,347 — 5,085 (2,578 ) 6,854 Total assets $ 41,154 $ 17,727 $ 158,041 $ (53,194 ) $ 163,728 Liabilities Deposit liabilities Noninterest-bearing $ — $ — $ 84 $ — $ 84 Interest-bearing 167 — 78,771 — 78,938 Total deposit liabilities 167 — 78,855 — 79,022 Short-term borrowings 3,622 — 9,051 — 12,673 Long-term debt 21,798 — 32,330 — 54,128 Intercompany debt to Bank subsidiary 330 — — (330 ) — Nonbank subsidiaries 1,027 — 2,903 (3,930 ) — Intercompany payables to Nonbank subsidiaries 153 — 351 (504 ) — Interest payable 253 — 98 — 351 Unearned insurance premiums and service revenue — — 2,500 — 2,500 Accrued expenses and other liabilities 487 — 3,911 (2,661 ) 1,737 Total liabilities 27,837 — 129,999 (7,425 ) 150,411 Total equity 13,317 17,727 28,042 (45,769 ) 13,317 Total liabilities and equity $ 41,154 $ 17,727 $ 158,041 $ (53,194 ) $ 163,728 (a) Amounts presented are based upon the legal transfer of the underlying assets to VIEs in order to reflect legal ownership.
Condensed Cash Flow Statement [Table Text Block]	Condensed Consolidating Statement of Cash Flows Three months ended March 31, 2017 ($ in millions) Parent Guarantors Nonguarantors Consolidating adjustments Ally consolidated Operating activities Net cash (used in) provided by operating activities $ (149 ) $ — $ 1,284 $ 40 $ 1,175 Investing activities Purchases of available-for-sale securities — — (2,833 ) — (2,833 ) Proceeds from sales of available-for-sale securities — — 1,045 — 1,045 Proceeds from maturities and repayments of available-for-sale securities — — 589 — 589 Purchases of held-to-maturity securities — — (215 ) — (215 ) Proceeds from maturities and repayments of held-to-maturity securities — — 5 — 5 Net change in investment securities — intercompany 1 — 261 (262 ) — Purchases of loans held-for-investment (15 ) — (390 ) — (405 ) Proceeds from sales of finance receivables and loans originated as held-for-investment — — 1,164 — 1,164 Originations and repayments of loans held-for-investment and other 931 — (1,145 ) (960 ) (1,174 ) Net change in loans — intercompany 1,146 — 170 (1,316 ) — Purchases of operating lease assets — — (893 ) — (893 ) Disposals of operating lease assets 1 — 1,544 — 1,545 Capital contributions to subsidiaries (83 ) — — 83 — Returns of contributed capital 645 — — (645 ) — Net change in restricted cash (27 ) — 385 (3 ) 355 Net change in nonmarketable equity investments — — 213 — 213 Other, net (26 ) — 58 (91 ) (59 ) Net cash provided by (used in) investing activities 2,573 — (42 ) (3,194 ) (663 ) Financing activities Net change in short-term borrowings — third party 1,278 — (5,581 ) — (4,303 ) Net (decrease) increase in deposits (82 ) — 5,533 — 5,451 Proceeds from issuance of long-term debt — third party 330 — 3,196 962 4,488 Repayments of long-term debt — third party (2,870 ) — (4,703 ) — (7,573 ) Net change in debt — intercompany (203 ) — (1,146 ) 1,349 — Repurchase of common stock (169 ) — — — (169 ) Dividends paid — third party (38 ) — — — (38 ) Dividends paid and returns of contributed capital — intercompany — — (686 ) 686 — Capital contributions from parent — — 83 (83 ) — Net cash used in financing activities (1,754 ) — (3,304 ) 2,914 (2,144 ) Effect of exchange-rate changes on cash and cash equivalents — — — — — Net increase (decrease) in cash and cash equivalents 670 — (2,062 ) (240 ) (1,632 ) Cash and cash equivalents at beginning of year 820 — 5,515 (401 ) 5,934 Cash and cash equivalents at March 31, $ 1,490 $ — $ 3,453 $ (641 ) $ 4,302 Three months ended March 31, 2016 ($ in millions) Parent Guarantors Nonguarantors Consolidating adjustments Ally consolidated Operating activities Net cash (used in) provided by operating activities $ (24 ) $ — $ 1,708 $ (482 ) $ 1,202 Investing activities Purchases of available-for-sale securities — — (4,870 ) — (4,870 ) Proceeds from sales of available-for-sale securities — — 4,175 — 4,175 Proceeds from maturities and repayments of available-for-sale securities — — 409 — 409 Purchases of held-to-maturity securities — — (118 ) — (118 ) Purchases of loans held-for-investment — — (1,402 ) — (1,402 ) Proceeds from sales of finance receivables and loans originated as held-for-investment — — 2,594 — 2,594 Originations and repayments of loans held-for-investment and other (292 ) — (392 ) — (684 ) Net change in loans — intercompany 683 — (44 ) (639 ) — Purchases of operating lease assets — — (701 ) — (701 ) Disposals of operating lease assets 2 — 1,533 — 1,535 Capital contributions to subsidiaries (128 ) — — 128 — Returns of contributed capital 223 — — (223 ) — Net change in restricted cash — — 48 — 48 Net change in nonmarketable equity investments — — (315 ) — (315 ) Other, net (32 ) — 12 — (20 ) Net cash provided by investing activities 456 — 929 (734 ) 651 Financing activities Net change in short-term borrowings — third party 187 — (2,926 ) — (2,739 ) Net (decrease) increase in deposits (10 ) — 3,790 — 3,780 Proceeds from issuance of long-term debt — third party 178 — 4,066 — 4,244 Repayments of long-term debt — third party (580 ) — (7,910 ) — (8,490 ) Net change in debt — intercompany (68 ) — (684 ) 752 — Repurchase of common stock (14 ) — — — (14 ) Dividends paid — third party (15 ) — — — (15 ) Dividends paid and returns of contributed capital — intercompany — — (705 ) 705 — Capital contributions from parent — — 128 (128 ) — Net cash used in financing activities (322 ) — (4,241 ) 1,329 (3,234 ) Effect of exchange-rate changes on cash and cash equivalents — — 2 — 2 Net increase (decrease) in cash and cash equivalents 110 — (1,602 ) 113 (1,379 ) Cash and cash equivalents at beginning of year 1,635 — 5,595 (850 ) 6,380 Cash and cash equivalents at March 31, $ 1,745 $ — $ 3,993 $ (737 ) $ 5,001

Description of Business, Basi58

Description of Business, Basis of Presentation, and Changes in Significant Accounting Policies Description of Business, Basis of Presentation, and Changes in Significant Accounting Policies (Details) $ in Millions	Mar. 31, 2016USD ($)
Accounting Standards Adopted or Issued [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 14

Acquisitions Acquisitions (Deta

Acquisitions Acquisitions (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Aug. 01, 2016	Jun. 01, 2016
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross			$ 28,000,000	$ 298,000,000
Amortization of Intangible Assets	$ 3,000,000
Goodwill	240,000,000	$ 240,000,000
Business Acquisition, Goodwill, Expected Tax Deductible Amount				0
Other Intangible Assets [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill				82,000,000
Cash and Cash Equivalents [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents				50,000,000
Other Assets [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill				14,000,000
Deferred Tax Asset [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill				4,000,000
Employee compensation and benefits [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents				40,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities				(41,000,000)
Other Liabilities [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities				(4,000,000)
Corporate and Other [Member]
Business Acquisition [Line Items]
Goodwill	193,000,000	193,000,000		$ 193,000,000
Automotive Finance Operations [Member]
Business Acquisition [Line Items]
Goodwill	$ 20,000,000	$ 20,000,000	$ 20,000,000

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Discontinued Operations and Disposal Groups [Abstract]
Disposal Group, Including Discontinued Operation, Operating Income (Loss)	$ 1	$ 4
Discontinued Operation, Tax Effect of Discontinued Operation	$ 0	$ 1

Other Income, Net of Losses (Sc

Other Income, Net of Losses (Schedule of Other Income, Net of Losses) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Other Nonoperating Income (Expense) [Abstract]
Remarketing Fees	$ 29	$ 28
Fees and Commissions, Other	27	25
Contractually Specified Servicing Fees, Late Fees, and Ancillary Fees Earned in Exchange for Servicing Financial Assets	16	13
Income (Loss) from Equity Method Investments	0	6
Other Income	43	23
Noninterest Income, Other Operating Income	$ 115	$ 95

Reserves for Insurance Losses62

Reserves for Insurance Losses and Loss Adjustment Expenses Reserves for Insurance Losses and Loss Adjustment Expenses (Schedule of Liability for Unpaid Claims and Claims Adjustment Expense) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Liability for Claims and Claims Adjustment Expenses (Rollforward) [Abstract]
Liability for Claims and Claims Adjustment Expense	$ 149	$ 169
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	108	120
Liability for Unpaid Claims and Claims Adjustment Expense, Net	41	49
Current Year Claims and Claims Adjustment Expense	89	77
Prior Year Claims and Claims Adjustment Expense	(1)	(4)
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	88	73
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year	(45)	(37)
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years	(23)	(22)
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid	(68)	(59)
Liability for Unpaid Claims and Claims Adjustment Expense, Foreign Currency Translation Gain (Loss)	2	3
Liability for Unpaid Claims and Claims Adjustment Expense, Net	63	66
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	112	118
Liability for Claims and Claims Adjustment Expense	$ 175	$ 184

Other Operating Expenses (Sched

Other Operating Expenses (Schedule Of Other Operating Expenses) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating Expenses [Abstract]
Insurance Commissions	$ 99	$ 94
Communications and Information Technology	69	66
Lease And Loan Administration	36	32
Marketing and Advertising Expense	30	27
Vehicle remarketing and repossession	28	24
Regulatory and licensing fees	27	21
Professional Fees	26	24
Depreciation, Nonproduction	22	21
Occupancy, Net	12	13
Taxes, Miscellaneous	8	9
Other Cost and Expense, Operating	48	54
Other Noninterest Expense	$ 405	$ 385

Investment Securities (Investme

Investment Securities (Investment Table) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 20,651	$ 19,293
Available-for-sale Securities, Gross Unrealized Gains	71	68
Available-for-sale Securities, Gross Unrealized Losses	(414)	(435)
Available-for-sale securities	20,308	18,926
Held-to-maturity securities	1,104	839
Held-to-maturity Securities, Unrecognized Holding Gain	2	0
Held-to-maturity Securities, Unrecognized Holding Loss	(43)	50
Held-to-maturity Securities, Fair Value	1,063	789
Deposit Assets	12	14
Pledged Assets Separately Reported, Securities Pledged for Federal Home Loan Bank, at Fair Value	3,235	4,881
Financial Instruments Owned and Pledged as Collateral, Amount Eligible to be Repledged by Counterparty	1,257	737
Cash Equivalents, at Carrying Value	1,100	291
Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	20,170	18,651
Available-for-sale Debt Securities Gross Unrealized Gain	62	61
Available-for-sale Debt Securities, Gross Unrealized Loss	(368)	(381)
Available-for-sale Securities, Debt Securities	19,864	18,331
US Treasury and Government [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	2,276	1,680
Available-for-sale Debt Securities Gross Unrealized Gain	1	0
Available-for-sale Debt Securities, Gross Unrealized Loss	(52)	(60)
Available-for-sale Securities, Debt Securities	2,225	1,620
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	803	794
Available-for-sale Debt Securities Gross Unrealized Gain	9	7
Available-for-sale Debt Securities, Gross Unrealized Loss	(17)	(19)
Available-for-sale Securities, Debt Securities	795	782
Foreign Government Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	143	157
Available-for-sale Debt Securities Gross Unrealized Gain	3	5
Available-for-sale Debt Securities, Gross Unrealized Loss	0	0
Available-for-sale Securities, Debt Securities	146	162
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	12,054	10,473
Available-for-sale Debt Securities Gross Unrealized Gain	31	29
Available-for-sale Debt Securities, Gross Unrealized Loss	(223)	(212)
Available-for-sale Securities, Debt Securities	11,862	10,290
Held-to-maturity securities	1,052	839
Held-to-maturity Securities, Unrecognized Holding Gain	2	0
Held-to-maturity Securities, Unrecognized Holding Loss	(43)	(50)
Held-to-maturity Securities, Fair Value	1,011	789
Residential Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	2,053	2,162
Available-for-sale Debt Securities Gross Unrealized Gain	4	5
Available-for-sale Debt Securities, Gross Unrealized Loss	(61)	(70)
Available-for-sale Securities, Debt Securities	1,996	2,097
Commercial Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	533	537
Available-for-sale Debt Securities Gross Unrealized Gain	2	2
Available-for-sale Debt Securities, Gross Unrealized Loss	(1)	(2)
Available-for-sale Securities, Debt Securities	534	537
Asset-backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1,046	1,396
Available-for-sale Debt Securities Gross Unrealized Gain	6	6
Available-for-sale Debt Securities, Gross Unrealized Loss	(1)	(2)
Available-for-sale Securities, Debt Securities	1,051	1,400
Held-to-maturity securities	52	0
Held-to-maturity Securities, Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Unrecognized Holding Loss	0	0
Held-to-maturity Securities, Fair Value	52	0
Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1,262	1,452
Available-for-sale Debt Securities Gross Unrealized Gain	6	7
Available-for-sale Debt Securities, Gross Unrealized Loss	(13)	(16)
Available-for-sale Securities, Debt Securities	1,255	1,443
Equity Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Equity Securities, Amortized Cost Basis	481	642
Available-for-sale Equity Securities, Gross Unrealized Gain	9	7
Available-for-sale Equity Securities, Gross Unrealized Loss	(46)	(54)
Available-for-sale Securities, Equity Securities	444	595
Federal Home Loan Bank Certificates and Obligations (FHLB) [Member]
Schedule of Investments [Line Items]
Held-to-maturity Securities, Fair Value	$ 0	$ 87

Investment Securities (Invest65

Investment Securities (Investments Classified by Contractual Maturity Date) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment		$ 839
Held-to-Maturity Debt Securities, Yield		2.90%
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount		$ 0
Held-to-Maturity Debt Securities, Due in One Year or Less, Yield		0.00%
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount		$ 0
Held-to-Maturity Debt Securities, Due After One Year Through Five Years, Yield		0.00%
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount		$ 0
Held-to-Maturity Debt Securities, Due After Five Years Through Ten Years, Yield		0.00%
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount		$ 839
Held-to-Maturity Securities, Due After Ten Years, Yield		2.90%
Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 19,864	$ 18,331
Available-for-sale debt securities, Yield	2.80%	2.80%
Available-for-sale debt securities, Due in one year or less, Amount	$ 165	$ 138
Available-for-sale debt securities, Due in one year or less, Yield	2.20%	2.00%
Available-for-sale debt securities, Due after one year through five years, Amount	$ 1,833	$ 2,046
Available-for-sale debt securities, Due after one year through five years, Yield	2.60%	2.70%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 2,751	$ 2,498
Available-for-sale debt securities, Due after five years through ten years, Yield	2.20%	2.20%
Available-for-sale debt securities, Due after ten years, Amount	$ 15,115	$ 13,649
Available-for-sale debt securities, Due after ten years, Yield	3.00%	2.90%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 20,170	$ 18,651
Amortized cost of available-for-sale debt securities, Due in one year or less, Amount	165	138
Amortized cost of available-for-sale debt securities, Due after one year through five years, Amount	1,826	2,040
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Amortized Cost Basis	2,806	2,563
Amortized cost of available-for-sale debt securities, Due after ten years, Amount	15,373	13,910
US Treasury and Government [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 2,225	$ 1,620
Available-for-sale debt securities, Yield	1.80%	1.70%
Available-for-sale debt securities, Due in one year or less, Amount	$ 0	$ 2
Available-for-sale debt securities, Due in one year or less, Yield	0.00%	4.60%
Available-for-sale debt securities, Due after one year through five years, Amount	$ 262	$ 60
Available-for-sale debt securities, Due after one year through five years, Yield	1.80%	1.60%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 1,963	$ 1,558
Available-for-sale debt securities, Due after five years through ten years, Yield	1.80%	1.70%
Available-for-sale debt securities, Due after ten years, Amount	$ 0	$ 0
Available-for-sale debt securities, Due after ten years, Yield	0.00%	0.00%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 2,276	$ 1,680
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 795	$ 782
Available-for-sale debt securities, Yield	3.10%	3.10%
Available-for-sale debt securities, Due in one year or less, Amount	$ 66	$ 64
Available-for-sale debt securities, Due in one year or less, Yield	2.40%	1.70%
Available-for-sale debt securities, Due after one year through five years, Amount	$ 34	$ 29
Available-for-sale debt securities, Due after one year through five years, Yield	2.50%	2.30%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 175	$ 172
Available-for-sale debt securities, Due after five years through ten years, Yield	2.90%	2.80%
Available-for-sale debt securities, Due after ten years, Amount	$ 520	$ 517
Available-for-sale debt securities, Due after ten years, Yield	3.30%	3.40%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 803	$ 794
Foreign Government Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 146	$ 162
Available-for-sale debt securities, Yield	2.50%	2.60%
Available-for-sale debt securities, Due in one year or less, Amount	$ 0	$ 0
Available-for-sale debt securities, Due in one year or less, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after one year through five years, Amount	$ 66	$ 58
Available-for-sale debt securities, Due after one year through five years, Yield	2.70%	2.80%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 80	$ 104
Available-for-sale debt securities, Due after five years through ten years, Yield	2.40%	2.40%
Available-for-sale debt securities, Due after ten years, Amount	$ 0	$ 0
Available-for-sale debt securities, Due after ten years, Yield	0.00%	0.00%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 143	$ 157
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 11,862	$ 10,290
Available-for-sale debt securities, Yield	3.00%	2.90%
Available-for-sale debt securities, Due in one year or less, Amount	$ 0	$ 0
Available-for-sale debt securities, Due in one year or less, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after one year through five years, Amount	$ 0	$ 0
Available-for-sale debt securities, Due after one year through five years, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 3	$ 29
Available-for-sale debt securities, Due after five years through ten years, Yield	2.90%	2.60%
Available-for-sale debt securities, Due after ten years, Amount	$ 11,859	$ 10,261
Available-for-sale debt securities, Due after ten years, Yield	3.00%	2.90%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 12,054	$ 10,473
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	$ 1,052
Held-to-Maturity Debt Securities, Yield	3.00%
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount	$ 0
Held-to-Maturity Debt Securities, Due in One Year or Less, Yield	0.00%
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	$ 0
Held-to-Maturity Debt Securities, Due After One Year Through Five Years, Yield	0.00%
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	$ 0
Held-to-Maturity Debt Securities, Due After Five Years Through Ten Years, Yield	0.00%
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount	$ 1,052
Held-to-Maturity Securities, Due After Ten Years, Yield	3.00%
Residential Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 1,996	$ 2,097
Available-for-sale debt securities, Yield	2.90%	2.90%
Available-for-sale debt securities, Due in one year or less, Amount	$ 0	$ 0
Available-for-sale debt securities, Due in one year or less, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after one year through five years, Amount	$ 0	$ 0
Available-for-sale debt securities, Due after one year through five years, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 0	$ 0
Available-for-sale debt securities, Due after five years through ten years, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after ten years, Amount	$ 1,996	$ 2,097
Available-for-sale debt securities, Due after ten years, Yield	2.90%	2.90%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 2,053	$ 2,162
Commercial Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 534	$ 537
Available-for-sale debt securities, Yield	2.80%	2.60%
Available-for-sale debt securities, Due in one year or less, Amount	$ 0	$ 0
Available-for-sale debt securities, Due in one year or less, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after one year through five years, Amount	$ 0	$ 0
Available-for-sale debt securities, Due after one year through five years, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 3	$ 3
Available-for-sale debt securities, Due after five years through ten years, Yield	2.80%	2.80%
Available-for-sale debt securities, Due after ten years, Amount	$ 531	$ 534
Available-for-sale debt securities, Due after ten years, Yield	2.80%	2.60%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 533	$ 537
Asset-backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 1,051	$ 1,400
Available-for-sale debt securities, Yield	2.90%	2.80%
Available-for-sale debt securities, Due in one year or less, Amount	$ 0	$ 0
Available-for-sale debt securities, Due in one year or less, Yield	0.00%	0.00%
Available-for-sale debt securities, Due after one year through five years, Amount	$ 829	$ 1,059
Available-for-sale debt securities, Due after one year through five years, Yield	2.90%	2.80%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 59	$ 143
Available-for-sale debt securities, Due after five years through ten years, Yield	3.20%	3.20%
Available-for-sale debt securities, Due after ten years, Amount	$ 163	$ 198
Available-for-sale debt securities, Due after ten years, Yield	2.60%	2.60%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 1,046	$ 1,396
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	$ 52
Held-to-Maturity Debt Securities, Yield	1.50%
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount	$ 10
Held-to-Maturity Debt Securities, Due in One Year or Less, Yield	0.80%
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	$ 40
Held-to-Maturity Debt Securities, Due After One Year Through Five Years, Yield	1.60%
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	$ 2
Held-to-Maturity Debt Securities, Due After Five Years Through Ten Years, Yield	2.70%
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount	$ 0
Held-to-Maturity Securities, Due After Ten Years, Yield	0.00%
Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 1,255	$ 1,443
Available-for-sale debt securities, Yield	2.90%	2.80%
Available-for-sale debt securities, Due in one year or less, Amount	$ 99	$ 72
Available-for-sale debt securities, Due in one year or less, Yield	2.10%	2.20%
Available-for-sale debt securities, Due after one year through five years, Amount	$ 642	$ 840
Available-for-sale debt securities, Due after one year through five years, Yield	2.60%	2.60%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 468	$ 489
Available-for-sale debt securities, Due after five years through ten years, Yield	3.20%	3.20%
Available-for-sale debt securities, Due after ten years, Amount	$ 46	$ 42
Available-for-sale debt securities, Due after ten years, Yield	4.70%	4.70%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 1,262	$ 1,452
Held-to-maturity Securities [Member]
Schedule of Investments [Line Items]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	$ 1,104
Held-to-Maturity Debt Securities, Yield	2.90%
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount	$ 10
Held-to-Maturity Debt Securities, Due in One Year or Less, Yield	0.80%
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	$ 40
Held-to-Maturity Debt Securities, Due After One Year Through Five Years, Yield	1.60%
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	$ 2
Held-to-Maturity Debt Securities, Due After Five Years Through Ten Years, Yield	2.70%
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount	$ 1,052
Held-to-Maturity Securities, Due After Ten Years, Yield	3.00%

Investment Securities (Invest66

Investment Securities (Investment Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Taxable interest	$ 119	$ 94
Taxable dividends	2	4
Interest and dividends exempt from U.S. federal income tax	5	4
Interest and Dividend Income, Securities, Operating, Available-for-sale	134	$ 102
Excludes Other Earning Assets [Member]
Interest and Dividend Income, Securities, Operating, Available-for-sale	$ 126

Investment Securities (Schedule

Investment Securities (Schedule Of Realized Gain (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Available-for-sale Securities [Abstract]
Available-for-sale Securities, Gross Realized Gains	$ 27
Available-for-sale Securities, Gross Realized Gain (Loss)		$ 54

Investment Securities (Schedu68

Investment Securities (Schedule of Unrealized Loss on Investments) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	$ 13,051	$ 12,356
Available-for-sale Securities, Unrealized Loss Less than 12 months	(311)	(317)
Available-for-sale Securities, Fair value 12 months or longer	1,792	2,038
Available-for-sale Securities, Unrealized Loss 12 months or longer	(103)	(118)
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	12,979	12,205
Available-for-sale Securities, Unrealized Loss Less than 12 months	(305)	(309)
Available-for-sale Securities, Fair value 12 months or longer	1,630	1,769
Available-for-sale Securities, Unrealized Loss 12 months or longer	(63)	(72)
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	2,070	1,612
Available-for-sale Securities, Unrealized Loss Less than 12 months	(52)	(60)
Available-for-sale Securities, Fair value 12 months or longer	0	0
Available-for-sale Securities, Unrealized Loss 12 months or longer	0	0
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	435	524
Available-for-sale Securities, Unrealized Loss Less than 12 months	(16)	(19)
Available-for-sale Securities, Fair value 12 months or longer	26	0
Available-for-sale Securities, Unrealized Loss 12 months or longer	(1)	0
Foreign Government Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	13	38
Available-for-sale Securities, Unrealized Loss Less than 12 months	0	0
Available-for-sale Securities, Fair value 12 months or longer	0	0
Available-for-sale Securities, Unrealized Loss 12 months or longer	0	0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	8,874	8,052
Available-for-sale Securities, Unrealized Loss Less than 12 months	(209)	(196)
Available-for-sale Securities, Fair value 12 months or longer	531	587
Available-for-sale Securities, Unrealized Loss 12 months or longer	(14)	(16)
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	768	813
Available-for-sale Securities, Unrealized Loss Less than 12 months	(16)	(17)
Available-for-sale Securities, Fair value 12 months or longer	816	860
Available-for-sale Securities, Unrealized Loss 12 months or longer	(45)	(53)
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	79	47
Available-for-sale Securities, Unrealized Loss Less than 12 months	(1)	(1)
Available-for-sale Securities, Fair value 12 months or longer	77	149
Available-for-sale Securities, Unrealized Loss 12 months or longer	0	(1)
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	175	375
Available-for-sale Securities, Unrealized Loss Less than 12 months	0	(2)
Available-for-sale Securities, Fair value 12 months or longer	134	127
Available-for-sale Securities, Unrealized Loss 12 months or longer	(1)	0
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	565	744
Available-for-sale Securities, Unrealized Loss Less than 12 months	(11)	(14)
Available-for-sale Securities, Fair value 12 months or longer	46	46
Available-for-sale Securities, Unrealized Loss 12 months or longer	(2)	(2)
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	72	151
Available-for-sale Securities, Unrealized Loss Less than 12 months	(6)	(8)
Available-for-sale Securities, Fair value 12 months or longer	162	269
Available-for-sale Securities, Unrealized Loss 12 months or longer	$ (40)	$ (46)

Finance Receivables and Loans69

Finance Receivables and Loans, Net (Schedule of Accounts, Notes, Loans and Financing Receivables) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 119,002	$ 118,944	$ 110,876
Derivative, Amount of Hedged Item	299	315
Loans and Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	393	359
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	76,600	76,843
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	65,663	65,793	63,013
Consumer Portfolio Segment [Member] | Automobile Loan [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Derivative, Amount of Hedged Item	34	43
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	10,937	11,050	10,675
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	8,331	8,294
Held For Investment Mortgage Finance Receivables Interest Only Mortgage Loans	$ 26	30
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | One year and nine months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	0.00%
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Two years and nine months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	37.00%
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Three years and nine months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	42.00%
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Four years and nine months, or greater [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	0.00%
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | nine months or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	3.00%
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 2,606	2,756
Held For Investment Mortgage Finance Receivables Interest Only Mortgage Loans	$ 653	714
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | One year and nine months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	2.00%
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Two years and nine months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	0.00%
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Three years and nine months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	0.00%
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Four years and nine months, or greater [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	1.00%
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | nine months or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	17.00%
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 42,402	42,101	$ 37,188
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	34,911	35,041
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	3,499	3,248
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 3,992	$ 3,812

Finance Receivables and Loans70

Finance Receivables and Loans, Net (Allowance for Credit Losses on Financing Receivables) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Financing Receivable, Allowance for Loan and Lease Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning Balance	$ 1,144	$ 1,054
Allowance for Loan and Lease Losses, Write-offs	(350)	(263)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	97	84
Allowance for Loan and Lease Losses Write-offs, Net	(253)	(179)
Provision for Loan and Lease Losses	(271)	(220)
Allowance for Loan and Lease Losses, Adjustments, Other	7	18
Loans and Leases Receivable, Allowance, Ending Balance	1,155	1,077
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	89	86
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,066	991
Loans and Leases Receivable, Gross	119,002	110,876	$ 118,944
Financing Receivable, Individually Evaluated for Impairment	757	688
Financing Receivable, Collectively Evaluated for Impairment	118,245	110,188
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Allowance for Loan and Lease Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning Balance	932	834
Allowance for Loan and Lease Losses, Write-offs	(341)	(253)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	90	80
Allowance for Loan and Lease Losses Write-offs, Net	(251)	(173)
Provision for Loan and Lease Losses	(267)	(207)
Allowance for Loan and Lease Losses, Adjustments, Other	7	18
Loans and Leases Receivable, Allowance, Ending Balance	941	850
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	32	25
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	909	825
Loans and Leases Receivable, Gross	65,663	63,013	65,793
Financing Receivable, Individually Evaluated for Impairment	388	337
Financing Receivable, Collectively Evaluated for Impairment	65,275	62,676
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Allowance for Loan and Lease Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning Balance	91	114
Allowance for Loan and Lease Losses, Write-offs	(9)	(10)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	7	4
Allowance for Loan and Lease Losses Write-offs, Net	(2)	(6)
Provision for Loan and Lease Losses	3	(7)
Allowance for Loan and Lease Losses, Adjustments, Other	0	0
Loans and Leases Receivable, Allowance, Ending Balance	86	115
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	33	43
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	53	72
Loans and Leases Receivable, Gross	10,937	10,675	11,050
Financing Receivable, Individually Evaluated for Impairment	249	261
Financing Receivable, Collectively Evaluated for Impairment	10,688	10,414
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Allowance for Loan and Lease Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning Balance	121	106
Allowance for Loan and Lease Losses, Write-offs	0	0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	0	0
Allowance for Loan and Lease Losses Write-offs, Net	0	0
Provision for Loan and Lease Losses	(7)	(6)
Allowance for Loan and Lease Losses, Adjustments, Other	0	0
Loans and Leases Receivable, Allowance, Ending Balance	128	112
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	24	18
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	104	94
Loans and Leases Receivable, Gross	42,402	37,188	$ 42,101
Financing Receivable, Individually Evaluated for Impairment	120	90
Financing Receivable, Collectively Evaluated for Impairment	$ 42,282	$ 37,098

Finance Receivables and Loans71

Finance Receivables and Loans, Net (Schedule of Sales of Financing Receivables and Loans) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Sales and Transfers	$ 1,216	$ 2,601
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Sales and Transfers	1,213	2,599
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Sales and Transfers	$ 3	$ 2

Finance Receivables and Loans72

Finance Receivables and Loans, Net Finance Receivables and Loans, Net (Schedule of Purchases of Financing Receivables and Loans) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Purchases	$ 395	$ 1,370
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Purchases	68	0
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Purchases	$ 327	$ 1,370

Finance Receivables and Loans73

Finance Receivables and Loans, Net (Past Due Financing Receivables and Loans) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 2,066	$ 2,759
Financing Receivable, Recorded Investment, Current	116,936	116,185
Loans and Leases Receivable, Gross	119,002	118,944	$ 110,876
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	2,060	2,749
Financing Receivable, Recorded Investment, Current	74,540	74,094
Loans and Leases Receivable, Gross	76,600	76,843
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,917	2,580
Financing Receivable, Recorded Investment, Current	63,746	63,213
Loans and Leases Receivable, Gross	65,663	65,793	63,013
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	143	169
Financing Receivable, Recorded Investment, Current	10,794	10,881
Loans and Leases Receivable, Gross	10,937	11,050	10,675
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	39	49
Financing Receivable, Recorded Investment, Current	8,292	8,245
Loans and Leases Receivable, Gross	8,331	8,294
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	104	120
Financing Receivable, Recorded Investment, Current	2,502	2,636
Loans and Leases Receivable, Gross	2,606	2,756
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	6	10
Financing Receivable, Recorded Investment, Current	42,396	42,091
Loans and Leases Receivable, Gross	42,402	42,101	$ 37,188
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	6	10
Financing Receivable, Recorded Investment, Current	34,905	35,031
Loans and Leases Receivable, Gross	34,911	35,041
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Financing Receivable, Recorded Investment, Current	3,499	3,248
Loans and Leases Receivable, Gross	3,499	3,248
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Financing Receivable, Recorded Investment, Current	3,992	3,812
Loans and Leases Receivable, Gross	3,992	3,812
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,409	1,937
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,409	1,934
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,346	1,850
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	63	84
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	30	39
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	33	45
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	3
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	3
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	324	452
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	324	452
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	308	428
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	16	24
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	2	6
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	14	18
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	333	370
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	327	363
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	263	302
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	64	61
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	7	4
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	57	57
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	6	7
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	6	7
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 0	$ 0

Finance Receivables and Loans74

Finance Receivables and Loans, Net (Schedule of Financing Receivables, Non Accrual Status) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 798	$ 819
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	678	697
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	573	598
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	105	99
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	10	10
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	95	89
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	120	122
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	34	33
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	81	84
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 5	$ 5

Finance Receivables and Loans75

Finance Receivables and Loans, Net (Financing Receivable Credit Quality Indicators) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 119,002	$ 118,944	$ 110,876
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	76,600	76,843
Consumer Portfolio Segment [Member] | Consumer Loan [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	75,922	76,146
Consumer Portfolio Segment [Member] | Consumer Loan [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	678	697
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	65,663	65,793	63,013
Consumer Portfolio Segment [Member] | Automobile Loan [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	65,090	65,195
Consumer Portfolio Segment [Member] | Automobile Loan [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	573	598
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	10,937	11,050	$ 10,675
Consumer Portfolio Segment [Member] | Residential Mortgage [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	10,832	10,951
Consumer Portfolio Segment [Member] | Residential Mortgage [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	105	99
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	8,331	8,294
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	8,321	8,284
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	10	10
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,606	2,756
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,511	2,667
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 95	$ 89

Finance Receivables and Loans76

Finance Receivables and Loans, Net (Schedule of Pass And Criticized Credit Quality Indicators of Finance Receivables) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 119,002	$ 118,944	$ 110,876
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	42,402	42,101	$ 37,188
Commercial Portfolio Segment [Member] | Commercial Loan [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	39,508	39,410
Commercial Portfolio Segment [Member] | Commercial Loan [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,894	2,691
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	34,911	35,041
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	32,878	33,160
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,033	1,881
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	3,499	3,248
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,814	2,597
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	685	651
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	3,992	3,812
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	3,816	3,653
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 176	$ 159

Finance Receivables and Loans77

Finance Receivables and Loans, Net (Impaired Financing Receivables) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	$ 812	$ 795
Impaired Financing Receivable, Recorded Investment	757	739
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	210	199
Impaired Financing Receivable, with Related Allowance, Recorded Investment	547	540
Impaired Financing Receivable, Related Allowance	89	85
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	675	658
Impaired Financing Receivable, Recorded Investment	637	617
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	184	190
Impaired Financing Receivable, with Related Allowance, Recorded Investment	453	427
Impaired Financing Receivable, Related Allowance	65	62
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	422	407
Impaired Financing Receivable, Recorded Investment	388	370
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	124	131
Impaired Financing Receivable, with Related Allowance, Recorded Investment	264	239
Impaired Financing Receivable, Related Allowance	32	28
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	253	251
Impaired Financing Receivable, Recorded Investment	249	247
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	60	59
Impaired Financing Receivable, with Related Allowance, Recorded Investment	189	188
Impaired Financing Receivable, Related Allowance	33	34
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	8	8
Impaired Financing Receivable, Recorded Investment	8	8
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	4	3
Impaired Financing Receivable, with Related Allowance, Recorded Investment	4	5
Impaired Financing Receivable, Related Allowance	0	0
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	245	243
Impaired Financing Receivable, Recorded Investment	241	239
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	56	56
Impaired Financing Receivable, with Related Allowance, Recorded Investment	185	183
Impaired Financing Receivable, Related Allowance	33	34
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	137	137
Impaired Financing Receivable, Recorded Investment	120	122
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	26	9
Impaired Financing Receivable, with Related Allowance, Recorded Investment	94	113
Impaired Financing Receivable, Related Allowance	24	23
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	34	33
Impaired Financing Receivable, Recorded Investment	34	33
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	7	7
Impaired Financing Receivable, with Related Allowance, Recorded Investment	27	26
Impaired Financing Receivable, Related Allowance	2	3
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	98	99
Impaired Financing Receivable, Recorded Investment	81	84
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	19	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	62	84
Impaired Financing Receivable, Related Allowance	21	19
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	5	5
Impaired Financing Receivable, Recorded Investment	5	5
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	2
Impaired Financing Receivable, with Related Allowance, Recorded Investment	5	3
Impaired Financing Receivable, Related Allowance	$ 1	$ 1

Finance Receivables and Loans78

Finance Receivables and Loans, Net (Schedule of Average Balance and Interest Income of Impaired Finance Receivables) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 749	$ 668
Impaired Financing Receivable, Interest Income, Accrual Method	7	7
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	628	590
Impaired Financing Receivable, Interest Income, Accrual Method	7	6
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	379	326
Impaired Financing Receivable, Interest Income, Accrual Method	5	4
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	249	264
Impaired Financing Receivable, Interest Income, Accrual Method	2	2
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	8	9
Impaired Financing Receivable, Interest Income, Accrual Method	0	0
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	241	255
Impaired Financing Receivable, Interest Income, Accrual Method	2	2
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	121	78
Impaired Financing Receivable, Interest Income, Accrual Method	0	1
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	33	23
Impaired Financing Receivable, Interest Income, Accrual Method	0	0
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	83	49
Impaired Financing Receivable, Interest Income, Accrual Method	0	1
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	5	6
Impaired Financing Receivable, Interest Income, Accrual Method	$ 0	$ 0

Finance Receivables and Loans79

Finance Receivables and Loans, Net (Troubled Debt Restructurings) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	$ 704		$ 663
Financing Receivable, Modifications, Number of Contracts	6,502	5,654
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 150	$ 94
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 134	$ 81
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	6,501	5,654
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 127	$ 94
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 111	$ 81
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	6,447	5,622
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 115	$ 89
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 99	$ 76
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	54	32
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 12	$ 5
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 12	$ 5
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	1	1
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 0	$ 1
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 1
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	53	31
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 12	$ 4
Financing Receivable, Modifications, Post-Modification Recorded Investment	12	$ 4
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Modifications [Line Items]
Loans and Leases Receivable, Impaired, Commitment to Lend	$ 3		$ 2
Financing Receivable, Modifications, Number of Contracts	1	0
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 23	$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 23	$ 0
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	0
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 0	$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 0
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	1	0
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 23	$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 23	$ 0
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	0
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 0	$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 0

Finance Receivables and Loans80

Finance Receivables and Loans, Net (Finance receivables and loans redefaulted during the period) (Details) - Consumer Portfolio Segment [Member] $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1,990	1,801
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 25	$ 23
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	$ 16	$ 12
Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1,989	1,800
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 24	$ 23
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	$ 16	$ 12
Mortgage Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	1	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 1	$ 0
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	$ 0	$ 0
Mortgage - Legacy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	$ 0	$ 0

Investment in Operating Lease81

Investment in Operating Leases, Net (Investments In Operating Leases) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Leases, Operating [Abstract]
Property Subject to or Available for Operating Lease, Gross	$ 13,240	$ 14,584
Property Subject to or Available for Operating Lease, Accumulated Depreciation	(2,779)	(3,114)
Property Subject to or Available for Operating Lease, Net	$ 10,461	$ 11,470

Investment in Operating Lease82

Investment in Operating Leases, Net (Schedule Of Depreciation Expense On Operating Lease Assets) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Leases, Operating [Abstract]
Depreciation Expense On Operating Lease Assets	$ 386	$ 565
Gross Remarketing (Gains) Losses	3	(55)
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	$ 389	$ 510

Securitizations and Variable 83

Securitizations and Variable Interest Entities (Schedule of Variable Interest Entities) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Variable Interest Entity [Line Items]
Assets of nonconsolidated variable interest entities	$ 3,571		$ 2,899
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	4,345		3,574
Carrying value of assets for VIEs for which we have continuing involvement	34,329		37,631
Carrying value of liabilities for VIEs for which we have continuing involvement	13,612		13,490
Retained notes and certificated residual interest	53
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale, Gain (Loss) on Sale	2	$ 0
Commercial Portfolio Segment [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	505		460
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	205		169
Assets of nonconsolidated variable interest entities	0		0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	695		651
Automobile Loan [Member] | Consumer Portfolio Segment [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	19,632		20,869
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	8,298		8,557
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	79		24
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	0		0
Assets of nonconsolidated variable interest entities	3,571		2,899
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	3,650		2,923
Automobile Loan [Member] | Consumer Portfolio Segment [Member] | Held-to-maturity Securities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	52
Automobile Loan [Member] | Consumer Portfolio Segment [Member] | Other Assets [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	27
Automobile Loan [Member] | Commercial Portfolio Segment [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	14,113		16,278
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	5,109		4,764
Unencumbered [Member] | Automobile Loan [Member] | Consumer Portfolio Segment [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	9,200		9,600
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	$ 64		$ 50

Securitizations and Variable 84

Securitizations and Variable Interest Entities (Schedule of Cash Flow Received from and Paid to Nonconsolidated Securitization Entities) (Details) - Consumer Portfolio Segment [Member] - Automobile Loan [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Cash Flows Between Transferor and Transferee, Proceeds from New Transfers	$ 1,138	$ 1,025
Cash Flows Between Transferor and Transferee, Servicing Fees	9	8
Cash Flows Between Transferor and Transferee, Receipts on Transferor's Interest in Transferred Financial Assets, Other	$ 2	$ 2

Securitizations and Variable 85

Securitizations and Variable Interest Entities (Schedule of Quantitative Information and Net Credit Losses about Securitized and Other Financial Assets Managed Together) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	$ 124,857		$ 124,500
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	674		841
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	257	$ 181
On-Balance Sheet Loans [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	119,003		118,944
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	657		822
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	253	179
On-Balance Sheet Loans [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	65,663		65,793
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	571		730
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	251	173
On-Balance Sheet Loans [Member] | Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	10,938		11,050
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	80		85
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	2	6
On-Balance Sheet Loans [Member] | Commercial Portfolio Segment [Member] | Automobile Loan [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	38,903		38,853
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	6		7
On-Balance Sheet Loans [Member] | Commercial Portfolio Segment [Member] | Other Financing Receivables [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	3,499		3,248
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	0		0
Off-Balance Sheet Loans [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	3,067		2,392
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	12		13
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	3	2
Off-Balance Sheet Loans [Member] | Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	3,067		2,392
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	12		13
Whole-Loan Transactions [Member]
Quantitative Information about Securitized and Other Financial Assets Managed Together [Line Items]
Principal Amount Outstanding on Loans Managed and Securitized or Asset-backed Financing Arrangement	2,787		3,164
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	5		$ 6
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	$ 1	$ 0

Servicing Activities (Schedule

Servicing Activities (Schedule of Total Serviced Automobile Loans Outstanding) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Automobile Serviced Assets [Line Items]
Contractually Specified Servicing Fees, Late Fees, and Ancillary Fees Earned in Exchange for Servicing Financial Assets	$ 16	$ 13
Total Primary Serviced Assets	120,693		$ 121,480
Consumer Loan [Member] | On-Balance Sheet Loans [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	65,464		65,646
Commercial Loan [Member] | On-Balance Sheet Loans [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	38,903		38,853
Operating Leases [Member] | On-Balance Sheet Loans [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	10,332		11,311
Other Assets [Member] | On-Balance Sheet Loans [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	67		67
Asset-backed Securities, Securitized Loans and Receivables [Member] | Off-Balance Sheet Loans [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	3,103		2,412
Whole-Loan Transactions [Member] | Off-Balance Sheet Loans [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	$ 2,824		$ 3,191

Other Assets (Schedule of Other

Other Assets (Schedule of Other Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Aug. 01, 2016	Jun. 01, 2016
Goodwill [Line Items]
Goodwill	$ 240	$ 240
Property, Plant and Equipment, Gross	939	901
Accumulated depreciation	(542)	(525)
Property, Plant and Equipment, Net	397	376
Restricted cash collections for securitization trusts	1,359	1,694
Deferred Tax Assets, State Taxes	900	994
Nonmarketable equity investments	833	1,046
Interest Receivable	457	476
Goodwill	240	240
Accounts and Other Receivables, Net, Current	165	100
Cash reserve deposits held for securitization trusts	164	184
Cash and securities collateral placed with counterparties	119	167
Restricted Cash and Cash Equivalents	111	111
Derivative Asset, Fair Value, Gross Asset	80	95
Other Assets, Miscellaneous	1,309	1,371
Other Assets	6,134	6,854
Federal Home Loan Bank Stock	359	577
Federal Reserve Bank Stock	435	435
Insurance Operations Member
Goodwill [Line Items]
Goodwill	27	27
Goodwill	27	27
Corporate and Other [Member]
Goodwill [Line Items]
Goodwill	193	193		$ 193
Goodwill	193	193		$ 193
Automotive Finance Operations [Member]
Goodwill [Line Items]
Goodwill	20	20	$ 20
Goodwill	$ 20	$ 20	$ 20

Deposit Liabilities (Schedule o

Deposit Liabilities (Schedule of Deposit Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Deposits [Abstract]
Noninterest-bearing deposit liabilities	$ 102	$ 84
Interest-bearing Deposit Liabilities, by Component [Abstract]
Deposits, Savings Deposits	51,150	46,976
Time Deposits	33,148	31,795
Deposits, Retail	86	167
Deposits	84,486	79,022
Time Deposits, $100,000 or More	12,200	12,100
Time Deposits, $250,000 or More, Domestic	$ 3,500	$ 3,500

Debt Debt (Schedule of Short-te

Debt Debt (Schedule of Short-term Debt) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Short-term Debt [Line Items]
Demand Notes	$ 3,652	$ 3,622
Federal Home Loan Bank, Advances, Maturities Summary, Due in Next Twelve Months	1,850	7,875
Securities Sold under Agreements to Repurchase, Gross	1,620	1,176
Other Short-term Borrowings	1,249	0
Short-term Debt	8,371	12,673
Non-derivative Cash Collateral Received from Counterparties Associated with the Repurchase Agreements.	1
Non-derivative Cash Collateral Placed with Counterparties Associated with the Repurchase Agreements	5	45
Unsecured Debt [Member]
Short-term Debt [Line Items]
Demand Notes	3,652	3,622
Federal Home Loan Bank, Advances, Maturities Summary, Due in Next Twelve Months	0	0
Securities Sold under Agreements to Repurchase, Gross	0	0
Other Short-term Borrowings	1,249	0
Short-term Debt	4,901	3,622
Secured Debt [Member]
Short-term Debt [Line Items]
Demand Notes	0	0
Federal Home Loan Bank, Advances, Maturities Summary, Due in Next Twelve Months	1,850	7,875
Securities Sold under Agreements to Repurchase, Gross	1,620	1,176
Other Short-term Borrowings	0	0
Short-term Debt	3,470	9,051
Maturity Less than 30 Days [Member] | Secured Debt [Member]
Short-term Debt [Line Items]
Mortgage-backed Residential Securities Sold under Agreements to Repurchase, Maturity Period	520
Maturity 31 to 60 Days [Member] | Secured Debt [Member]
Short-term Debt [Line Items]
Mortgage-backed Residential Securities Sold under Agreements to Repurchase, Maturity Period	0
Maturity 61 to 90 Days [Member] [Member] | Secured Debt [Member]
Short-term Debt [Line Items]
Mortgage-backed Residential Securities Sold under Agreements to Repurchase, Maturity Period	626
One year, or less [Member] | Secured Debt [Member]
Short-term Debt [Line Items]
Asset-backed Automotive Financial Securities Sold under Agreements to Repurchase, Maturity Period	474	$ 500
Committed Funding Facilities Member | Nonbank Funding Member | Unsecured Debt [Member]
Short-term Debt [Line Items]
Debt Issuance Costs, Net	$ 1

Debt (Schedule of Debt) (Detail

Debt (Schedule of Debt) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term Debt, Current Maturities	$ 11,377	$ 14,553
Long-term Debt, Excluding Current Maturities	39,385	39,260
Derivative, Amount of Hedged Item	299	315
Long-term debt	51,061	54,128
Secured Debt	37,001	43,129
Unsecured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Current Maturities	2,329	4,274
Long-term Debt, Excluding Current Maturities	14,893	15,450
Derivative, Amount of Hedged Item	308	326
Long-term debt	17,530	20,050
Secured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Current Maturities	9,048	10,279
Long-term Debt, Excluding Current Maturities	24,492	23,810
Derivative, Amount of Hedged Item	(9)	(11)
Long-term debt	33,531	34,078
Trust Preferred Securities Subject to Mandatory Redemption [Member]
Debt Instrument [Line Items]
Long-term Debt, Excluding Current Maturities	2,600	2,600
Federal Home Loan Bank Advances [Member]
Debt Instrument [Line Items]
Secured Debt	$ 6,100	$ 6,100

Debt (Scheduled Remaining Matur

Debt (Scheduled Remaining Maturity of Long-term Debt) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	$ 9,317
Long-term Debt, Maturities, Repayments of Principal in Year Two	12,133
Long-term Debt, Maturities, Repayments of Principal in Year Three	9,722
Long-term Debt, Maturities, Repayments of Principal in Year Four	7,372
Long-term Debt, Maturities, Repayments of Principal in Year Five	3,154
Long-term Debt, Maturities, Repayments of Principal after Year Five	9,064
Derivative, Amount of Hedged Item	299	$ 315
Long-term debt	51,061	54,128
Unsecured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	1,742
Long-term Debt, Maturities, Repayments of Principal in Year Two	3,599
Long-term Debt, Maturities, Repayments of Principal in Year Three	1,642
Long-term Debt, Maturities, Repayments of Principal in Year Four	2,197
Long-term Debt, Maturities, Repayments of Principal in Year Five	596
Long-term Debt, Maturities, Repayments of Principal after Year Five	7,446
Derivative, Amount of Hedged Item	308	326
Long-term debt	17,530	20,050
Debt Instrument, Unamortized Discount	(69)
Debt Instrument, Unamortized Discount	(1,304)
Unsecured Debt [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount, Noncurrent	(101)
Unsecured Debt [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount, Noncurrent	(39)
Unsecured Debt [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount, Noncurrent	(39)
Unsecured Debt [Member] | Debt Instrument, Redemption, Period Four [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount, Noncurrent	(42)
Unsecured Debt [Member] | Debt Instrument, Redemption, Period Five [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount, Noncurrent	(1,014)
Secured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	7,575
Long-term Debt, Maturities, Repayments of Principal in Year Two	8,534
Long-term Debt, Maturities, Repayments of Principal in Year Three	8,080
Long-term Debt, Maturities, Repayments of Principal in Year Four	5,175
Long-term Debt, Maturities, Repayments of Principal in Year Five	2,558
Long-term Debt, Maturities, Repayments of Principal after Year Five	1,618
Derivative, Amount of Hedged Item	(9)	(11)
Long-term debt	33,531	$ 34,078
Long-term Debt [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	1,811
Long-term Debt, Maturities, Repayments of Principal in Year Two	3,700
Long-term Debt, Maturities, Repayments of Principal in Year Three	1,681
Long-term Debt, Maturities, Repayments of Principal in Year Four	2,236
Long-term Debt, Maturities, Repayments of Principal in Year Five	638
Long-term Debt, Maturities, Repayments of Principal after Year Five	8,460
Derivative, Amount of Hedged Item	308
Long-term debt	18,834
original issue discount [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Derivative, Amount of Hedged Item	$ 0

Debt (Pledged Assets Related to

Debt (Pledged Assets Related to Secured Borrowings and Repurchase Agreement) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Pledged Assets related to secured borrowings [Line Items]
Pledged Financial Instruments, Not Separately Reported, Other Debt Securities Available-for-sale or Held-for-investment	$ 3,175	$ 4,895
Pledged Assets, Mortgage assets held for investment	10,847	10,954
Pledged Assets, Investment in operating leases	1,412	2,040
Pledged Assets, Other, Not Separately Reported on Statement of Financial Position	59,755	65,222
Secured Debt	37,001	43,129
Short-term Debt	8,371	12,673
Ally Bank [Member]
Pledged Assets related to secured borrowings [Line Items]
Pledged Financial Instruments, Not Separately Reported, Other Debt Securities Available-for-sale or Held-for-investment	1,978	4,231
Pledged Assets, Mortgage assets held for investment	10,847	10,954
Pledged Assets, Investment in operating leases	314	913
Pledged Assets, Other, Not Separately Reported on Statement of Financial Position	35,371	41,129
Secured Debt	15,120	22,149
Pledged assets for Federal Home Loan Bank [Member] | Ally Bank [Member]
Pledged Assets related to secured borrowings [Line Items]
Pledged Assets, Other, Not Separately Reported on Statement of Financial Position	16,800	19,000
Pledged assets for Federal Reserve Bank [Member] | Ally Bank [Member]
Pledged Assets related to secured borrowings [Line Items]
Pledged Assets, Other, Not Separately Reported on Statement of Financial Position	2,300	2,400
Secured Debt [Member]
Pledged Assets related to secured borrowings [Line Items]
Short-term Debt	3,470	9,051
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Pledged Assets related to secured borrowings [Line Items]
Pledged Assets, Not Separately Reported, Finance Receivables	26,420	27,846
Consumer Portfolio Segment [Member] | Automobile Loan [Member] | Ally Bank [Member]
Pledged Assets related to secured borrowings [Line Items]
Pledged Assets, Not Separately Reported, Finance Receivables	4,523	5,751
Commercial Portfolio Segment [Member] | Automobile Loan [Member]
Pledged Assets related to secured borrowings [Line Items]
Pledged Assets, Not Separately Reported, Finance Receivables	17,901	19,487
Commercial Portfolio Segment [Member] | Automobile Loan [Member] | Ally Bank [Member]
Pledged Assets related to secured borrowings [Line Items]
Pledged Assets, Not Separately Reported, Finance Receivables	$ 17,709	$ 19,280

Debt Debt (Narrative - Trust Pr

Debt Debt (Narrative - Trust Preferred Securities) (Details) $ / shares in Units, $ in Billions	Mar. 31, 2017USD ($)$ / shares
Narrative - Trust Preferred Securities [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.00%
Preferred Stock, Liquidation Preference Per Share | $ / shares	$ 25
From and including February 15, 2016, to but excluding February 15, 2040, distributions will be payable at an annual rate equal to three-month London interbank offer rate plus:	0.00%
Ally has the right to defer payments of interest for a period not exceeding consecutive quarters of:	20
Percent of principle debt, plus accrued and unpaid interest is the redemption price if Ally redeems the Series 2 TRUPS on or after February 15, 2016.	100.00%
Fixed Income Interest Rate [Member]
Narrative - Trust Preferred Securities [Line Items]
Trust preferred securities | $	$ 2.6

Debt (Committed Funding Facilit

Debt (Committed Funding Facilities) (Details) - Committed Funding Facilities Member - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 16,425	$ 18,375
Long-term Line of Credit	15,423	14,800
Unused capacity	1,002	3,575
Bank Funding Member | Secured Debt [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	2,400	3,600
Long-term Line of Credit	2,050	3,250
Unused capacity	350	350
Revolving secured funding facilities [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	15,600
Revolving secured funding facilities 1 year or greater [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	3,100
Nonbank Funding Member | Secured Debt [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	12,775	13,525
Long-term Line of Credit	12,123	11,550
Unused capacity	652	1,975
Nonbank Funding Member | Unsecured Debt [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,250	1,250
Long-term Line of Credit	1,250	0
Unused capacity	$ 0	$ 1,250

Accrued Expenses and Other Li95

Accrued Expenses and Other Liabilities (Schedule of Accrued Expenses and Other Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Accounts Payable and Accrued Liabilities [Abstract]
Accounts Payable	$ 851	$ 649
Liability for Claims and Claims Adjustment Expense	175	149	$ 184	$ 169
Accrued Employee Benefits	156	232
Derivative Liability, Fair Value, Gross Liability	81	95
Deferred Revenue	47	56
Cash and securities collateral placed with counterparties	12	10
Other Accrued Liabilities	600	546
Accounts Payable and Accrued Liabilities	$ 1,922	$ 1,737

Accumulated Other Comprehensi96

Accumulated Other Comprehensive Loss (Rollforward) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax [Abstract]
Beginning Balance Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	$ (273)	$ (159)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	21	142
Ending Balance Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	(252)	(17)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax [Abstract]
Beginning Balance Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	14	9
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	0	5
Ending Balance Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	14	14
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax [Abstract]
Beginning Balance Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	8	8
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent	0	0
Ending Balance Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	8	8
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax [Abstract]
Beginning Balance Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(90)	(89)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent	(1)	(1)
Ending Balance Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(91)	(90)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(341)	(231)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	20	146
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (321)	$ (85)

Accumulated Other Comprehensi97

Accumulated Other Comprehensive Loss (Before and After Tax) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, [Abstract]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax	$ 51	$ 280
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax	27	54
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent	24	226
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax [Abstract]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	(5)	(104)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax	(2)	(20)
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax, Portion Attributable to Parent	(3)	(84)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax [Abstract]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	46	176
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax	25	34
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	21	142
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax [Abstract]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax	2	13
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax [Abstract]
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	(1)	(5)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax [Abstract]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	1	8
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax [Abstract]
Other Comprehensive Income Unrealized Gain Loss On Net Investment Hedges Arising During the Period, Before Tax	(2)	(6)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax Effect [Abstract]
Other Comprehensive Income Unrealized Gain Loss On Net Investment Hedges Arising During the Period, Tax	1	3
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax [Abstract]
Other Comprehensive Income Unrealized Gain Loss On Net Investment Hedges Arising During the Period Net of Tax	(1)	(3)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax, [Abstract]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	(1)	(1)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax [Abstract]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax	0	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax [Abstract]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Net of Tax	(1)	(1)
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	23	232
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	3	86
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ 20	$ 146

Earnings per Common Share (Sche

Earnings per Common Share (Schedule of Basic and Diluted Earnings per Common Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	$ 213	$ 247
Dividends, Preferred Stock, Cash	0	(15)
Net income (loss) from continuing operations attributable to common shareholders	213	232
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	1	3
Net Income (Loss) Available to Common Stockholders, Basic	$ 214	$ 235
Weighted Average Number of Shares Outstanding, Basic	465,961,123	484,233,246
Weighted Average Number of Shares Outstanding, Diluted	466,829,404	484,654,229
Earnings Per Share, Basic [Abstract]
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.46	$ 0.48
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0	0.01
Earnings Per Share, Basic	0.46	0.49
Earnings Per Share, Diluted [Abstract]
Income (Loss) from Continuing Operations, Per Diluted Share	0.46	0.48
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0	0.01
Earnings Per Share, Diluted	$ 0.46	$ 0.49

Regulatory Capital and Other 99

Regulatory Capital and Other Regulatory Matters (Schedule of Regulatory Capital Amount and Ratios) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Apr. 14, 2017	Dec. 31, 2016	Oct. 18, 2016	Jul. 18, 2016
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 Capital Required for Capital Adequacy to Risk-weighted Assets	4.50%		4.50%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%		6.00%
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%		8.00%
Common equity Tier 1 capital conservation buffer	2.50%		2.50%
Federal Reserve Bank Stock	$ 435		$ 435		$ 435
assets greater than $50 billion	$ 50,000		$ 50,000
Dividends Payable, Amount Per Share	$ 0.08		$ 0.08			$ 0.08	$ 0.08
Stock Repurchase Program, Authorized Amount	$ 700		$ 700
Treasury Stock, Value, Acquired, Cost Method	$ 169	$ 14	$ 495
Treasury Stock, Common, Shares	25,140,190		25,140,190
Reduction in total shares outstanding	5.20%		5.20%
Common Stock, Shares, Outstanding	462,193,424		462,193,424		467,000,306
Subsequent Event [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Dividends Payable, Amount Per Share				$ 0.08
Parent Company [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 Capital Required for Capital Adequacy to Risk-weighted Assets	4.50%		4.50%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%		6.00%
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%		8.00%
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%		4.00%
Common Equity Tier 1 Capital	$ 12,923		$ 12,923		$ 12,978
Percentage of Common Equity Tier 1 Capital to Risk-weighted Assets	9.40%		9.40%		9.37%
Tier One Risk Based Capital	$ 15,245		$ 15,245		$ 15,147
Tier One Risk Based Capital to Risk Weighted Assets	11.09%		11.09%		10.93%
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.00%		6.00%
Capital	$ 17,459		$ 17,459		$ 17,419
Capital to Risk Weighted Assets	12.70%		12.70%		12.57%
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%		10.00%
Tier One Leverage Capital	$ 15,245		$ 15,245		$ 15,147
Tier One Leverage Capital to Average Assets	9.51%		9.51%		9.54%
Subsidiaries [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 Capital Required for Capital Adequacy to Risk-weighted Assets	4.50%		4.50%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%		6.00%
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%		8.00%
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	15.00%		15.00%
Common Equity Tier 1 Capital	$ 18,562		$ 18,562		$ 17,888
Percentage of Common Equity Tier 1 Capital to Risk-weighted Assets	17.74%		17.74%		16.70%
Common Equity Tier 1 Capital Required to be Well Capitalized to Risk-weighted Assets	6.50%		6.50%
Tier One Risk Based Capital	$ 18,562		$ 18,562		$ 17,888
Tier One Risk Based Capital to Risk Weighted Assets	17.74%		17.74%		16.70%
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%		8.00%
Capital	$ 19,167		$ 19,167		$ 18,458
Capital to Risk Weighted Assets	18.32%		18.32%		17.24%
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%		10.00%
Tier One Leverage Capital	$ 18,562		$ 18,562		$ 17,888
Tier One Leverage Capital to Average Assets	15.38%		15.38%		15.21%
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%		5.00%

Derivative Instruments and H100

Derivative Instruments and Hedging Activities (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash Collateral Placed with Counterparties Excluding Cash Collateral Associated with Repurchase Agreements	$ 115	$ 122
Securities Collateral Placed with Counterparties	59	72
Non-derivative Cash Collateral Placed with Counterparties Associated with the Repurchase Agreements	5	45
Cash Collateral Received from Counterparties, Excluding Collateral Associated with Repurchase Agreements	12	10
Non-derivative Cash Collateral Received from Counterparties Associated with the Repurchase Agreements.	1
Non-cash collateral received	$ 6	$ 6

Derivative Instruments and H101

Derivative Instruments and Hedging Activities (Fair Value Amounts of Derivative Instruments Reported on our Condensed Consolidated Balance Sheet) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 80	$ 95
Derivative Liability, Fair Value, Gross Liability	81	95
Derivative, Notional Amount	31,090	34,166
Interest Receivable	457	476
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	18	20
Derivative Liability, Fair Value, Gross Liability	18	21
Derivative, Notional Amount	4,089	4,902
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	18	19
Derivative Liability, Fair Value, Gross Liability	17	21
Derivative, Notional Amount	3,939	4,731
Hedge notional amount associated with debt maturing in five or more years	2,600
Foreign Exchange Forward [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	1
Derivative Liability, Fair Value, Gross Liability	1	0
Derivative, Notional Amount	150	171
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	62	73
Derivative Liability, Fair Value, Gross Liability	62	73
Derivative, Notional Amount	26,907	29,172
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	1
Derivative Liability, Fair Value, Gross Liability	1	0
Derivative, Notional Amount	94	92
Equity Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	1
Derivative Liability, Fair Value, Gross Liability	0	1
Derivative, Notional Amount	0	0
Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Receive-fixed Swaps, Fair Value, Gross Asset	11	8
Receive-fixed Swaps, Fair Value, Gross Liability	18	14
Receive-fixed Swaps, Notional Amount	2,600	1,700
Pay-fixed Swaps, Fair Value, Gross Asset	7	10
Pay-fixed Swaps, Fair Value, Gross Liability	0	1
Pay-fixed Swaps, Notional Amount	1,400	2,800
Interest Rate Swap [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Notional Amount	43	137
Foreign Exchange Forward [Member] | Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	1
Derivative Liability, Fair Value, Gross Liability	1	0
Derivative, Notional Amount	94	92
Futures and Forwards [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Notional Amount	25	0
Written Options [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	62	73
Derivative, Notional Amount	13,432	14,518
Written Options [Member] | Equity Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	1
Derivative, Notional Amount	0	0
Purchased Options [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	62	73
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Notional Amount	13,407	14,517
Purchased Options [Member] | Equity Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	1
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Notional Amount	0	0
Other Trading [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	62	75
Derivative Liability, Fair Value, Gross Liability	63	74
Derivative, Notional Amount	27,001	29,264
Secured Debt [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Receive-fixed Swaps, Fair Value, Gross Asset	0	0
Receive-fixed Swaps, Fair Value, Gross Liability	0	7
Receive-fixed Swaps, Notional Amount	0	240
Derivative assets in net asset position [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	78	87
Interest Receivable	3	7
Derivative assets in net liability positions [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	2	8
Interest Receivable	$ 0	$ 1

Derivative Instruments and H102

Derivative Instruments and Hedging Activities (Statement of Gains and Losses on Derivative Instruments Reported in Statement of Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ (1)	$ (5)
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(4)	(9)
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	(2)	2
Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	(1)	(5)
Equity Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	(1)
Interest Income [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	2	(28)
Interest Income [Member] | Interest Rate Contract [Member] | Hedges of Retail Auto Loans Held for Investment [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	1	7
Interest Income [Member] | Interest Rate Contract [Member] | Losses Related to Amortization of Deferred Basis Adjustments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	5	5
Interest Income [Member] | Interest Rate Contract [Member] | Gains Related to Amortization of Deferred Basis Adjustments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	20	18
Interest Income [Member] | Interest Rate Contract [Member] | Losses Related to Amortization of Deferred Basis Adjustments (FHLB) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	1	0
Interest Income [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(4)	28
Interest Expense [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	4	191
Interest Expense [Member] | Interest Rate Contract [Member] | Hedges of Unsecured Debt Held for Investment [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	5	16
Interest Expense [Member] | Interest Rate Contract [Member] | Hedges of Secured Debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	1
Interest Expense [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(3)	(196)
Interest Expense [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	0	(1)
Other Income [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	(2)	2
Other Income [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	(1)	(4)
Other Income [Member] | Foreign Exchange Contract [Member] | Revaluation of Foreign-Denominated Debt or Receivable [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	1	4
Employee compensation and benefits [Member] | Equity Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ 0	$ (1)

Derivative Instruments and H103

Derivative Instruments and Hedging Activities (Derivative Instruments Used in Net Investment Hedge Accounting Relationships) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Cumulative Translation Adjustment, Net of Tax, Period Increase (Decrease)	$ 3	$ 11
Foreign Exchange Contract [Member] | Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ (2)	$ (6)

Income Taxes Income Taxes (Inco

Income Taxes Income Taxes (Income Tax Expense) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income Tax Expense (Benefit)	$ 113	$ 150

Fair Value (Fair Value Measurme

Fair Value (Fair Value Measurment - Recurring Basis) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 20,308	$ 18,926
Derivative Assets	65	74
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	$ (60)	$ (70)
Available-for-sale, Equity Investment in Any One Industry Did Not Exceed Percentage	16.00%	14.00%
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 20,308	$ 18,926
Mortgages Held-for-sale, Fair Value Disclosure	1
Retained Interest, Fair Value Disclosure	31	29
Derivative Assets	80	95
Assets, Fair Value Disclosure	20,420	19,050
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(81)	(95)
Liabilities, Fair Value Disclosure	(81)	(95)
Fair Value, Measurements, Recurring [Member] | Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(80)	(94)
Fair Value, Measurements, Recurring [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(1)
Fair Value, Measurements, Recurring [Member] | Other Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure		(1)
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	19,864	18,331
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,225	1,620
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	795	782
Fair Value, Measurements, Recurring [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	146	162
Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	11,862	10,290
Fair Value, Measurements, Recurring [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,996	2,097
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	534	537
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,051	1,400
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,255	1,443
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	444	595
Fair Value, Measurements, Recurring [Member] | Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	80	92
Fair Value, Measurements, Recurring [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets		2
Fair Value, Measurements, Recurring [Member] | Other Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets		1
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,678	2,226
Mortgages Held-for-sale, Fair Value Disclosure	0
Retained Interest, Fair Value Disclosure	0	0
Derivative Assets	0	1
Assets, Fair Value Disclosure	2,678	2,227
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0	(1)
Liabilities, Fair Value Disclosure	0	(1)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure		(1)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,234	1,631
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US Treasury and Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,225	1,620
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	9	11
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	444	595
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets		1
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	17,630	16,700
Mortgages Held-for-sale, Fair Value Disclosure	0
Retained Interest, Fair Value Disclosure	0	0
Derivative Assets	80	94
Assets, Fair Value Disclosure	17,710	16,794
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(81)	(94)
Liabilities, Fair Value Disclosure	(81)	(94)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(80)	(94)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(1)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	17,630	16,700
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US Treasury and Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	795	782
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	137	151
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	11,862	10,290
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,996	2,097
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	534	537
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,051	1,400
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,255	1,443
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	80	92
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets		2
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Mortgages Held-for-sale, Fair Value Disclosure	1
Retained Interest, Fair Value Disclosure	31	29
Derivative Assets	0	0
Assets, Fair Value Disclosure	32	29
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | US Treasury and Government [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	$ 0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets		$ 0

Fair Value (Fair Value Measurem

Fair Value (Fair Value Measurement - Reconciliation of Level 3 Assets And Liabilities) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Assets, Beginning balance	$ 29	$ 40
Net realized/unrealized gains (losses) included in earnings, Assets	0	2
Net realized/unrealized gains (losses) included in other comprehensive income, Assets	0	0
Purchases, Assets	3	0
Sales, Assets	2	4
Issuances, Assets	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(2)	(15)
Fair Value, Assets, Ending balance	32	31
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0
Loans Held-for-Sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Assets, Beginning balance	0
Net realized/unrealized gains (losses) included in earnings, Assets	0
Net realized/unrealized gains (losses) included in other comprehensive income, Assets	0
Purchases, Assets	3
Sales, Assets	(2)
Issuances, Assets	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	0
Fair Value, Assets, Ending balance	1
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0
Retained Interest [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Assets, Beginning balance	29	40
Net realized/unrealized gains (losses) included in earnings, Assets	0	2
Net realized/unrealized gains (losses) included in other comprehensive income, Assets	0	0
Purchases, Assets	0	0
Sales, Assets	4	4
Issuances, Assets	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(2)	(15)
Fair Value, Assets, Ending balance	31	31
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 0	$ 0

Fair Value (Fair Value Measu107

Fair Value (Fair Value Measurement - Nonrecurring Basis) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	$ 1	$ 0
Fair Value, Measurements, Nonrecurring [Member] | Loans held-for-sale, Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group			$ 39
Lower of cost or fair value or valuation reserve allowance			0
Fair Value, Measurements, Nonrecurring [Member] | Commercial Finance Receivables And Loans, Automotive [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial Finance Receivables and Loans, Net, Fair Value	29		17
Lower of cost or fair value or valuation reserve allowance	(3)		(3)
Fair Value, Measurements, Nonrecurring [Member] | Commercial Finance Receivables And Loans, Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial Finance Receivables and Loans, Net, Fair Value	61		28
Lower of cost or fair value or valuation reserve allowance	(21)		(15)
Fair Value, Measurements, Nonrecurring [Member] | Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial Finance Receivables and Loans, Net, Fair Value	90		45
Lower of cost or fair value or valuation reserve allowance	(24)		(18)
Fair Value, Measurements, Nonrecurring [Member] | Repossessed And Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	15		12
Lower of cost or fair value or valuation reserve allowance	(2)		(3)
Fair Value, Measurements, Nonrecurring [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	4		6
Lower of cost or fair value or valuation reserve allowance	0		0
Fair Value, Measurements, Nonrecurring [Member] | Assets, Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	109		102
Lower of cost or fair value or valuation reserve allowance	(26)		(21)
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Loans held-for-sale, Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group			0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial Finance Receivables And Loans, Automotive [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial Finance Receivables and Loans, Net, Fair Value	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial Finance Receivables And Loans, Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial Finance Receivables and Loans, Net, Fair Value	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial Finance Receivables and Loans, Net, Fair Value	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Repossessed And Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Assets, Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Loans held-for-sale, Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group			0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial Finance Receivables And Loans, Automotive [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial Finance Receivables and Loans, Net, Fair Value	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial Finance Receivables And Loans, Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial Finance Receivables and Loans, Net, Fair Value	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial Finance Receivables and Loans, Net, Fair Value	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Repossessed And Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Assets, Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Loans held-for-sale, Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group			39
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial Finance Receivables And Loans, Automotive [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial Finance Receivables and Loans, Net, Fair Value	29		17
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial Finance Receivables And Loans, Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial Finance Receivables and Loans, Net, Fair Value	61		28
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial Finance Receivables and Loans, Net, Fair Value	90		45
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Repossessed And Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	15		12
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	4		6
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Assets, Total [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 109		$ 102

Fair Value Fair Value (Fair Val

Fair Value Fair Value (Fair Value Measurements - Nonrecurring Fair Value Inputs) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	$ 1	$ 0

Fair Value (Fair Value of Finan

Fair Value (Fair Value of Financial Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	$ 1,104	$ 839
Loans and Leases Receivable, Net Amount	117,847	117,800
Nonmarketable equity investments	833	1,046
Deposits	84,486	79,022
Short-term Debt	8,371	12,673
Long-term Debt	51,061	54,128
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	1,104	839
Loans and Leases Receivable, Net Amount	117,847	117,800
Nonmarketable equity investments	833	1,046
Deposits	84,486	79,022
Short-term Debt	8,371	12,673
Long-term Debt	51,061	54,128
Portion at Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	1,063	789
Loans and Leases Receivable, Net Amount	119,420	118,750
Nonmarketable equity investments	854	1,067
Deposits	82,715	78,469
Short-term Debt	8,372	12,675
Long-term Debt	53,115	56,120
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	0	0
Loans and Leases Receivable, Net Amount	0	0
Nonmarketable equity investments	0	0
Deposits	0	0
Short-term Debt	0	0
Long-term Debt	0	0
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	1,063	789
Loans and Leases Receivable, Net Amount	0	0
Nonmarketable equity investments	795	1,012
Deposits	0	0
Short-term Debt	0	0
Long-term Debt	19,604	22,036
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	0	0
Loans and Leases Receivable, Net Amount	119,420	118,750
Nonmarketable equity investments	59	55
Deposits	82,715	78,469
Short-term Debt	8,372	12,675
Long-term Debt	$ 33,511	$ 34,084

Offsetting Assets and Liabil110

Offsetting Assets and Liabilities Offsetting Assets and Liabilities (Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 80	$ 95
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	80	95
Derivative Asset, Not Subject to Master Netting Arrangement	(7)	(12)
Derivative, Collateral, Obligation to Return Cash	(8)	(9)
Derivative Asset	65	74
Customer Securities for which Entity has Right to Sell or Repledge, Fair Value	6	6
Derivative assets in net asset position [Member]
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset	78	87
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	78	87
Derivative Asset, Not Subject to Master Netting Arrangement	(5)	(4)
Derivative, Collateral, Obligation to Return Cash	(8)	(9)
Derivative Asset	65	74
Derivative assets in net liability positions [Member]
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset	2	8
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	2	8
Derivative Asset, Not Subject to Master Netting Arrangement	(2)	(8)
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset	$ 0	$ 0

Offsetting Assets and Liabil111

Offsetting Assets and Liabilities Offsetting Assets and Liabilities (Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ (81)	$ (95)
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(81)	(95)
Derivative Liability, Not Subject to Master Netting Arrangement Deduction	7	12
Derivative, Collateral, Right to Reclaim Cash	14	13
Derivative Liability	(60)	(70)
Customer Securities for which Entity has Right to Sell or Repledge, Fair Value	6	6
Derivative Liabilities in Net Liability Positions [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	(76)	(91)
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(76)	(91)
Derivative Liability, Not Subject to Master Netting Arrangement Deduction	2	8
Derivative, Collateral, Right to Reclaim Cash	14	13
Derivative Liability	(60)	(70)
Derivative liabilities in net asset positions [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	(5)	(4)
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(5)	(4)
Derivative Liability, Not Subject to Master Netting Arrangement Deduction	5	4
Derivative, Collateral, Right to Reclaim Cash	0	0
Derivative Liability	0	0
Securities sold under agreement to repurchase [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	(1,146)	(676)
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(1,146)	(676)
Derivative Liability, Not Subject to Master Netting Arrangement Deduction	0	0
Derivative, Collateral, Right to Reclaim Cash	1,146	676
Derivative Liability	0	0
Total Derivative Liabilities [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	(1,227)	(771)
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(1,227)	(771)
Derivative Liability, Not Subject to Master Netting Arrangement Deduction	7	12
Derivative, Collateral, Right to Reclaim Cash	1,160	689
Derivative Liability	$ (60)	$ (70)

Segment Information (Financial

Segment Information (Financial Information Operating Segments) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net Financing Revenue	$ 979	$ 951
Nonoperating Income (Expense)	396	376
Revenues	1,375	1,327
Provision for Loan Losses Expensed	271	220
Noninterest Expense	778	710
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	326	397
Assets	162,101	156,505	$ 163,728
Net Interest Income (Loss) after Provision for Loan Losses	708	731
Automotive Finance Operations [Member]
Segment Reporting Information [Line Items]
Net Financing Revenue	892	896
Nonoperating Income (Expense)	101	77
Revenues	993	973
Provision for Loan Losses Expensed	268	209
Noninterest Expense	437	427
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	288	337
Assets	115,154	112,289
Insurance Operations Member
Segment Reporting Information [Line Items]
Net Financing Revenue	15	14
Nonoperating Income (Expense)	264	254
Revenues	279	268
Provision for Loan Losses Expensed	0	0
Noninterest Expense	239	218
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	40	50
Assets	7,230	7,194
Mortgage Finance Operations [Member]
Segment Reporting Information [Line Items]
Net Financing Revenue	34	20
Nonoperating Income (Expense)	0	0
Revenues	34	20
Provision for Loan Losses Expensed	1	3
Noninterest Expense	24	15
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	9	2
Assets	8,362	7,493
Corporate Finance Operations [Member]
Segment Reporting Information [Line Items]
Net Financing Revenue	34	28
Nonoperating Income (Expense)	18	6
Revenues	52	34
Provision for Loan Losses Expensed	6	6
Noninterest Expense	21	17
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	25	11
Assets	3,438	2,839
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Net Financing Revenue	4	(7)
Nonoperating Income (Expense)	13	39
Revenues	17	32
Provision for Loan Losses Expensed	(4)	2
Noninterest Expense	57	33
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(36)	(3)
Assets	$ 27,917	$ 26,690

Parent and Guarantor Condens113

Parent and Guarantor Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statement of Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	$ 1,368	$ 1,235
Interest and Dividend Income, Securities, Operating	134	102
Interest Income, Deposits with Financial Institutions	5	3
Operating Leases, Income Statement, Lease Revenue	543	769
Total financing revenue and other interest income	2,050	2,109
Interest Expense, Deposits	231	193
Interest Expense, Short-term Borrowings	27	13
Interest Expense, Long-term Debt	424	442
Interest Expense, Related Party	0	0
Interest Expense	682	648
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	389	510
Net Financing Revenue	979	951
Dividends From Non Bank Subsidiary	0	0
Insurance Services Revenue	241	230
Gain (Loss) on Sales of Loans, Net	14	1
Gain (Loss) on Extinguishment of Debt	(1)	(4)
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	27	54
Noninterest Income, Other Operating Income	115	95
Nonoperating Income (Expense)	396	376
Revenues	1,375	1,327
Provision for Loan Losses Expensed	271	220
Labor and Related Expense	285	252
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	88	73
Other Noninterest Expense	405	385
Noninterest Expense	778	710
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	326	397
Income Tax Expense (Benefit)	113	150
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	213	247
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	1	3
Undistributed income of bank subsidiaries	0	0
Undistributed income of nonbank subsidiaries	0	0
Net Income (Loss) Attributable to Parent	214	250
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	20	146
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	234	396
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	(35)	(38)
Interest and Dividend Income, Securities, Operating	0	0
Interest Income, Deposits with Financial Institutions	2	1
Operating Leases, Income Statement, Lease Revenue	3	5
Total financing revenue and other interest income	(26)	(29)
Interest Expense, Deposits	1	2
Interest Expense, Short-term Borrowings	17	10
Interest Expense, Long-term Debt	281	289
Interest Expense, Related Party	4	4
Interest Expense	303	305
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	2	4
Net Financing Revenue	(331)	(338)
Dividends From Non Bank Subsidiary	41	482
Insurance Services Revenue	0	0
Gain (Loss) on Sales of Loans, Net	(2)	(3)
Gain (Loss) on Extinguishment of Debt	0	(2)
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	0	0
Noninterest Income, Other Operating Income	268	374
Nonoperating Income (Expense)	266	369
Revenues	(24)	513
Provision for Loan Losses Expensed	107	60
Labor and Related Expense	122	147
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	0	0
Other Noninterest Expense	288	340
Noninterest Expense	410	487
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(541)	(34)
Income Tax Expense (Benefit)	(134)	(43)
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(407)	9
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	2	6
Undistributed income of bank subsidiaries	389	270
Undistributed income of nonbank subsidiaries	230	(35)
Net Income (Loss) Attributable to Parent	214	250
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	20	146
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	234	396
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	0	0
Interest and Dividend Income, Securities, Operating	0	0
Interest Income, Deposits with Financial Institutions	0	0
Operating Leases, Income Statement, Lease Revenue	0	0
Total financing revenue and other interest income	0	0
Interest Expense, Deposits	0	0
Interest Expense, Short-term Borrowings	0	0
Interest Expense, Long-term Debt	0	0
Interest Expense, Related Party	0	0
Interest Expense	0	0
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	0	0
Net Financing Revenue	0	0
Dividends From Non Bank Subsidiary	0	0
Insurance Services Revenue	0	0
Gain (Loss) on Sales of Loans, Net	0	0
Gain (Loss) on Extinguishment of Debt	0	0
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	0	0
Noninterest Income, Other Operating Income	0	0
Nonoperating Income (Expense)	0	0
Revenues	0	0
Provision for Loan Losses Expensed	0	0
Labor and Related Expense	0	0
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	0	0
Other Noninterest Expense	0	0
Noninterest Expense	0	0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	0	0
Income Tax Expense (Benefit)	0	0
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	0	0
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	0
Undistributed income of bank subsidiaries	389	270
Undistributed income of nonbank subsidiaries	0	0
Net Income (Loss) Attributable to Parent	389	270
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	5	84
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	394	354
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	1,403	1,273
Interest and Dividend Income, Securities, Operating	135	102
Interest Income, Deposits with Financial Institutions	3	2
Operating Leases, Income Statement, Lease Revenue	540	764
Total financing revenue and other interest income	2,085	2,145
Interest Expense, Deposits	230	191
Interest Expense, Short-term Borrowings	10	3
Interest Expense, Long-term Debt	143	153
Interest Expense, Related Party	4	3
Interest Expense	387	350
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	387	506
Net Financing Revenue	1,311	1,289
Dividends From Non Bank Subsidiary	0	0
Insurance Services Revenue	241	230
Gain (Loss) on Sales of Loans, Net	16	4
Gain (Loss) on Extinguishment of Debt	(1)	(2)
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	27	54
Noninterest Income, Other Operating Income	224	217
Nonoperating Income (Expense)	507	503
Revenues	1,818	1,792
Provision for Loan Losses Expensed	164	160
Labor and Related Expense	163	105
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	88	73
Other Noninterest Expense	494	542
Noninterest Expense	745	720
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	909	912
Income Tax Expense (Benefit)	247	193
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	662	719
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	(1)	(3)
Undistributed income of bank subsidiaries	0	0
Undistributed income of nonbank subsidiaries	0	0
Net Income (Loss) Attributable to Parent	661	716
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	19	151
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	680	867
Affiliated Entity [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	0	0
Interest Income, Deposits with Financial Institutions	0	0
Affiliated Entity [Member] | Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	4	3
Interest Income, Deposits with Financial Institutions	0	0
Affiliated Entity [Member] | Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	0	0
Interest Income, Deposits with Financial Institutions	0	0
Affiliated Entity [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	3	2
Interest Income, Deposits with Financial Institutions	1	2
Consolidation, Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	0	0
Interest and Dividend Income, Securities, Operating	(1)	0
Interest Income, Deposits with Financial Institutions	0	0
Operating Leases, Income Statement, Lease Revenue	0	0
Total financing revenue and other interest income	(9)	(7)
Interest Expense, Deposits	0	0
Interest Expense, Short-term Borrowings	0	0
Interest Expense, Long-term Debt	0	0
Interest Expense, Related Party	(8)	(7)
Interest Expense	(8)	(7)
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	0	0
Net Financing Revenue	(1)	0
Dividends From Non Bank Subsidiary	(41)	(482)
Insurance Services Revenue	0	0
Gain (Loss) on Sales of Loans, Net	0	0
Gain (Loss) on Extinguishment of Debt	0	0
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	0	0
Noninterest Income, Other Operating Income	(377)	(496)
Nonoperating Income (Expense)	(377)	(496)
Revenues	(419)	(978)
Provision for Loan Losses Expensed	0	0
Labor and Related Expense	0	0
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	0	0
Other Noninterest Expense	(377)	(497)
Noninterest Expense	(377)	(497)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(42)	(481)
Income Tax Expense (Benefit)	0	0
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(42)	(481)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	0
Undistributed income of bank subsidiaries	(778)	(540)
Undistributed income of nonbank subsidiaries	(230)	35
Net Income (Loss) Attributable to Parent	(1,050)	(986)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(24)	(235)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	(1,074)	(1,221)
Consolidation, Eliminations [Member] | Affiliated Entity [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	(7)	(5)
Interest Income, Deposits with Financial Institutions	$ (1)	$ (2)

Parent and Guarantor Condens114

Parent and Guarantor Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Balance Sheet) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and Due from Banks	$ 1,513	$ 1,547
Interest-bearing Deposits in Banks and Other Financial Institutions	2,789	4,387
Cash and Cash Equivalents, at Carrying Value	4,302	5,934	$ 5,001	$ 6,380
Trading Securities		0
Available-for-sale securities	20,308	18,926
Held-to-maturity securities	1,104	839
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	1	0
Loans and Leases Receivable, Gross	119,002	118,944	110,876
Loans to bank subsidiary	0	0
Loans to nonbank subsidiary	0	0
Loans and Leases Receivable, Allowance	(1,155)	(1,144)	(1,077)	(1,054)
Loans and Leases Receivable, Net Amount	117,847	117,800
Property Subject to or Available for Operating Lease, Net	10,461	11,470
Receivables from bank subsidiary	0	0
Receivables from nonbank subsidiary	0	0
Investment in bank subsidiaries	0	0
Investment in nonbank subsidiaries	0	0
Premiums receivable and other insurance assets	1,944	1,905
Other Assets	6,134	6,854
Assets	162,101	163,728	156,505
Noninterest-bearing deposit liabilities	102	84
Interest-bearing Deposit Liabilities	84,384	78,938
Deposits	84,486	79,022
Short-term Debt	8,371	12,673
Long-term Debt	51,061	54,128
Debt Payable To Bank Subsidiaries	0	0
Debt Payable To Nonbank Subsidiaries	0	0
Payables to Bank Subsidiaries	0
Payables to Nonbank Subsidiaries	0	0
Interest payable	382	351
Unearned Premiums	2,514	2,500
Accounts Payable and Accrued Liabilities	1,922	1,737
Liabilities	148,736	150,411
Stockholders' Equity Attributable to Parent	13,365	13,317	13,823	13,439
Liabilities and Equity	162,101	163,728
Parent Company [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and Due from Banks	690	720
Interest-bearing Deposits in Banks and Other Financial Institutions	800	100
Cash and Cash Equivalents, at Carrying Value	1,490	820	1,745	1,635
Trading Securities		0
Available-for-sale securities	6	0
Held-to-maturity securities	0	0
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	0
Loans and Leases Receivable, Gross	4,864	4,705
Loans to bank subsidiary	425	1,125
Loans to nonbank subsidiary	1,376	1,779
Loans and Leases Receivable, Allowance	(121)	(115)
Loans and Leases Receivable, Net Amount	6,544	7,494
Property Subject to or Available for Operating Lease, Net	35	42
Receivables from bank subsidiary	32	299
Receivables from nonbank subsidiary	46	107
Investment in bank subsidiaries	18,405	17,727
Investment in nonbank subsidiaries	9,680	10,318
Premiums receivable and other insurance assets	0	0
Other Assets	4,275	4,347
Assets	40,513	41,154
Noninterest-bearing deposit liabilities	0	0
Interest-bearing Deposit Liabilities	85	167
Deposits	85	167
Short-term Debt	4,901	3,622
Long-term Debt	20,156	21,798
Debt Payable To Bank Subsidiaries	51	330
Debt Payable To Nonbank Subsidiaries	1,097	1,027
Payables to Bank Subsidiaries	127
Payables to Nonbank Subsidiaries	180	153
Interest payable	231	253
Unearned Premiums	0	0
Accounts Payable and Accrued Liabilities	320	487
Liabilities	27,148	27,837
Stockholders' Equity Attributable to Parent	13,365	13,317
Liabilities and Equity	40,513	41,154
Guarantor Subsidiaries [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and Due from Banks	0	0
Interest-bearing Deposits in Banks and Other Financial Institutions	0	0
Cash and Cash Equivalents, at Carrying Value	0	0	0	0
Trading Securities		0
Available-for-sale securities	0	0
Held-to-maturity securities	0	0
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	0
Loans and Leases Receivable, Gross	0	0
Loans to bank subsidiary	0	0
Loans to nonbank subsidiary	0	0
Loans and Leases Receivable, Allowance	0	0
Loans and Leases Receivable, Net Amount	0	0
Property Subject to or Available for Operating Lease, Net	0	0
Receivables from bank subsidiary	0	0
Receivables from nonbank subsidiary	0	0
Investment in bank subsidiaries	18,405	17,727
Investment in nonbank subsidiaries	0	0
Premiums receivable and other insurance assets	0	0
Other Assets	0	0
Assets	18,405	17,727
Noninterest-bearing deposit liabilities	0	0
Interest-bearing Deposit Liabilities	0	0
Deposits	0	0
Short-term Debt	0	0
Long-term Debt	0	0
Debt Payable To Bank Subsidiaries	0	0
Debt Payable To Nonbank Subsidiaries	0	0
Payables to Bank Subsidiaries	0
Payables to Nonbank Subsidiaries	0	0
Interest payable	0	0
Unearned Premiums	0	0
Accounts Payable and Accrued Liabilities	0	0
Liabilities	0	0
Stockholders' Equity Attributable to Parent	18,405	17,727
Liabilities and Equity	18,405	17,727
Non-Guarantor Subsidiaries [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and Due from Banks	823	827
Interest-bearing Deposits in Banks and Other Financial Institutions	1,989	4,287
Cash and Cash Equivalents, at Carrying Value	3,453	5,515	3,993	5,595
Trading Securities		82
Available-for-sale securities	20,308	19,253
Held-to-maturity securities	1,155	839
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	1
Loans and Leases Receivable, Gross	114,138	114,239
Loans to bank subsidiary	0	0
Loans to nonbank subsidiary	456	626
Loans and Leases Receivable, Allowance	(1,034)	(1,029)
Loans and Leases Receivable, Net Amount	113,560	113,836
Property Subject to or Available for Operating Lease, Net	10,426	11,428
Receivables from bank subsidiary	0	0
Receivables from nonbank subsidiary	255	67
Investment in bank subsidiaries	0	0
Investment in nonbank subsidiaries	0	0
Premiums receivable and other insurance assets	1,974	1,936
Other Assets	4,764	5,085
Assets	155,896	158,041
Noninterest-bearing deposit liabilities	102	84
Interest-bearing Deposit Liabilities	84,299	78,771
Deposits	84,401	78,855
Short-term Debt	3,470	9,051
Long-term Debt	30,905	32,330
Debt Payable To Bank Subsidiaries	0	0
Debt Payable To Nonbank Subsidiaries	1,807	2,903
Payables to Bank Subsidiaries	0
Payables to Nonbank Subsidiaries	57	351
Interest payable	151	98
Unearned Premiums	2,514	2,500
Accounts Payable and Accrued Liabilities	4,506	3,911
Liabilities	127,811	129,999
Stockholders' Equity Attributable to Parent	28,085	28,042
Liabilities and Equity	155,896	158,041
Affiliated Entity [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Interest-bearing Deposits in Banks and Other Financial Institutions	0	0
Affiliated Entity [Member] | Parent Company [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Interest-bearing Deposits in Banks and Other Financial Institutions	0	0
Affiliated Entity [Member] | Guarantor Subsidiaries [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Interest-bearing Deposits in Banks and Other Financial Institutions	0	0
Affiliated Entity [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Interest-bearing Deposits in Banks and Other Financial Institutions	641	401
Consolidation, Eliminations [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and Due from Banks	0	0
Interest-bearing Deposits in Banks and Other Financial Institutions	0	0
Cash and Cash Equivalents, at Carrying Value	(641)	(401)	$ (737)	$ (850)
Trading Securities		(82)
Available-for-sale securities	(6)	(327)
Held-to-maturity securities	(51)	0
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	0
Loans and Leases Receivable, Gross	0	0
Loans to bank subsidiary	(425)	(1,125)
Loans to nonbank subsidiary	(1,832)	(2,405)
Loans and Leases Receivable, Allowance	0	0
Loans and Leases Receivable, Net Amount	(2,257)	(3,530)
Property Subject to or Available for Operating Lease, Net	0	0
Receivables from bank subsidiary	(32)	(299)
Receivables from nonbank subsidiary	(301)	(174)
Investment in bank subsidiaries	(36,810)	(35,454)
Investment in nonbank subsidiaries	(9,680)	(10,318)
Premiums receivable and other insurance assets	(30)	(31)
Other Assets	(2,905)	(2,578)
Assets	(52,713)	(53,194)
Noninterest-bearing deposit liabilities	0	0
Interest-bearing Deposit Liabilities	0	0
Deposits	0	0
Short-term Debt	0	0
Long-term Debt	0	0
Debt Payable To Bank Subsidiaries	(51)	(330)
Debt Payable To Nonbank Subsidiaries	(2,904)	(3,930)
Payables to Bank Subsidiaries	(127)
Payables to Nonbank Subsidiaries	(237)	(504)
Interest payable	0	0
Unearned Premiums	0	0
Accounts Payable and Accrued Liabilities	(2,904)	(2,661)
Liabilities	(6,223)	(7,425)
Stockholders' Equity Attributable to Parent	(46,490)	(45,769)
Liabilities and Equity	(52,713)	(53,194)
Consolidation, Eliminations [Member] | Affiliated Entity [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Interest-bearing Deposits in Banks and Other Financial Institutions	$ (641)	$ (401)

Parent and Guarantor Condens115

Parent and Guarantor Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statement of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	$ 1,175	$ 1,202
Payments to Acquire Available-for-sale Securities	(2,833)	(4,870)
Proceeds from sales of available-for-sale securities	1,045	4,175
Proceeds from maturities and repayment of available-for-sale securities	589	409
Payments to Acquire Held-to-maturity Securities	(215)	(118)
Proceeds from Sale and Maturity of Held-to-maturity Securities	5	0
Payments to Acquire Loans Held-for-investment	405	1,402
Proceeds from Sale of Loans Held-for-sale	1,164	2,594
Originations and repayments of loans held-for-investment and other	(1,174)	(684)
Purchases of operating lease assets	(893)	(701)
Disposals of operating lease assets	1,545	1,535
Capital contributions to subsidiaries	0	0
Returns of contributed capital	0	0
Increase (Decrease) in Restricted Cash	355	48
Increase (Decrease) in Non marketable equity securities	213	(315)
Payments for (Proceeds from) Other Investing Activities	(59)	(20)
Net cash provided by investing activities	(663)	651
Proceeds from (Repayments of) Short-term Debt	(4,303)	(2,739)
Increase (Decrease) in Deposits	5,451	3,780
Proceeds from issuance of long-term debt	4,488	4,244
Repayments of long-term debt	(7,573)	(8,490)
Net Change in Debt, Intercompany	0	0
Payments for Repurchase of Common Stock	(169)	(14)
Payments of Dividends	(38)	(15)
Dividends paid and returns of contributed capital, Intercompany	0	0
Capital contributions from parent	0	0
Net cash (used in) provided by financing activities	(2,144)	(3,234)
Effect of exchange-rate changes on cash and cash equivalents	0	2
Cash and Cash Equivalents, Period Increase (Decrease)	(1,632)	(1,379)
Cash and Cash Equivalents, at Carrying Value	5,934	6,380
Cash and Cash Equivalents, at Carrying Value	4,302	5,001
Parent Company [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(149)	(24)
Payments to Acquire Available-for-sale Securities	0	0
Proceeds from sales of available-for-sale securities	0	0
Proceeds from maturities and repayment of available-for-sale securities	0	0
Payments to Acquire Held-to-maturity Securities	0	0
Proceeds from Sale and Maturity of Held-to-maturity Securities	0
Payments to Acquire Loans Held-for-investment	15	0
Proceeds from Sale of Loans Held-for-sale	0	0
Originations and repayments of loans held-for-investment and other	931	(292)
Purchases of operating lease assets	0	0
Disposals of operating lease assets	1	2
Capital contributions to subsidiaries	(83)	(128)
Returns of contributed capital	645	223
Increase (Decrease) in Restricted Cash	(27)	0
Increase (Decrease) in Non marketable equity securities	0	0
Payments for (Proceeds from) Other Investing Activities	(26)	(32)
Net cash provided by investing activities	2,573	456
Proceeds from (Repayments of) Short-term Debt	1,278	187
Increase (Decrease) in Deposits	(82)	(10)
Proceeds from issuance of long-term debt	330	178
Repayments of long-term debt	(2,870)	(580)
Net Change in Debt, Intercompany	(203)	(68)
Payments for Repurchase of Common Stock	(169)	(14)
Payments of Dividends	(38)	(15)
Dividends paid and returns of contributed capital, Intercompany	0	0
Capital contributions from parent	0	0
Net cash (used in) provided by financing activities	(1,754)	(322)
Effect of exchange-rate changes on cash and cash equivalents	0	0
Cash and Cash Equivalents, Period Increase (Decrease)	670	110
Cash and Cash Equivalents, at Carrying Value	820	1,635
Cash and Cash Equivalents, at Carrying Value	1,490	1,745
Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	0	0
Payments to Acquire Available-for-sale Securities	0	0
Proceeds from sales of available-for-sale securities	0	0
Proceeds from maturities and repayment of available-for-sale securities	0	0
Payments to Acquire Held-to-maturity Securities	0	0
Proceeds from Sale and Maturity of Held-to-maturity Securities	0
Payments to Acquire Loans Held-for-investment	0	0
Proceeds from Sale of Loans Held-for-sale	0	0
Originations and repayments of loans held-for-investment and other	0	0
Purchases of operating lease assets	0	0
Disposals of operating lease assets	0	0
Capital contributions to subsidiaries	0	0
Returns of contributed capital	0	0
Increase (Decrease) in Restricted Cash	0	0
Increase (Decrease) in Non marketable equity securities	0	0
Payments for (Proceeds from) Other Investing Activities	0	0
Net cash provided by investing activities	0	0
Proceeds from (Repayments of) Short-term Debt	0	0
Increase (Decrease) in Deposits	0	0
Proceeds from issuance of long-term debt	0	0
Repayments of long-term debt	0	0
Net Change in Debt, Intercompany	0	0
Payments for Repurchase of Common Stock	0	0
Payments of Dividends	0	0
Dividends paid and returns of contributed capital, Intercompany	0	0
Capital contributions from parent	0	0
Net cash (used in) provided by financing activities	0	0
Effect of exchange-rate changes on cash and cash equivalents	0	0
Cash and Cash Equivalents, Period Increase (Decrease)	0	0
Cash and Cash Equivalents, at Carrying Value	0	0
Cash and Cash Equivalents, at Carrying Value	0	0
Non-Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	1,284	1,708
Payments to Acquire Available-for-sale Securities	(2,833)	(4,870)
Proceeds from sales of available-for-sale securities	1,045	4,175
Proceeds from maturities and repayment of available-for-sale securities	589	409
Payments to Acquire Held-to-maturity Securities	(215)	(118)
Proceeds from Sale and Maturity of Held-to-maturity Securities	5
Payments to Acquire Loans Held-for-investment	390	1,402
Proceeds from Sale of Loans Held-for-sale	1,164	2,594
Originations and repayments of loans held-for-investment and other	(1,145)	(392)
Purchases of operating lease assets	(893)	(701)
Disposals of operating lease assets	1,544	1,533
Capital contributions to subsidiaries	0	0
Returns of contributed capital	0	0
Increase (Decrease) in Restricted Cash	385	48
Increase (Decrease) in Non marketable equity securities	213	(315)
Payments for (Proceeds from) Other Investing Activities	58	12
Net cash provided by investing activities	(42)	929
Proceeds from (Repayments of) Short-term Debt	(5,581)	(2,926)
Increase (Decrease) in Deposits	5,533	3,790
Proceeds from issuance of long-term debt	3,196	4,066
Repayments of long-term debt	(4,703)	(7,910)
Net Change in Debt, Intercompany	(1,146)	(684)
Payments for Repurchase of Common Stock	0	0
Payments of Dividends	0	0
Dividends paid and returns of contributed capital, Intercompany	(686)	(705)
Capital contributions from parent	83	128
Net cash (used in) provided by financing activities	(3,304)	(4,241)
Effect of exchange-rate changes on cash and cash equivalents	0	2
Cash and Cash Equivalents, Period Increase (Decrease)	(2,062)	(1,602)
Cash and Cash Equivalents, at Carrying Value	5,515	5,595
Cash and Cash Equivalents, at Carrying Value	3,453	3,993
Affiliated Entity [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Payments for (Proceeds from) Investments	0
Payments for (Proceeds from) Loans and Leases	0	0
Affiliated Entity [Member] | Parent Company [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Payments for (Proceeds from) Investments	(1)
Payments for (Proceeds from) Loans and Leases	1,146	683
Affiliated Entity [Member] | Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Payments for (Proceeds from) Investments	0
Payments for (Proceeds from) Loans and Leases	0	0
Affiliated Entity [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Payments for (Proceeds from) Investments	(261)
Payments for (Proceeds from) Loans and Leases	170	(44)
Consolidation, Eliminations [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	40	(482)
Payments to Acquire Available-for-sale Securities	0	0
Proceeds from sales of available-for-sale securities	0	0
Proceeds from maturities and repayment of available-for-sale securities	0	0
Payments to Acquire Held-to-maturity Securities	0	0
Proceeds from Sale and Maturity of Held-to-maturity Securities	0
Payments to Acquire Loans Held-for-investment	0	0
Proceeds from Sale of Loans Held-for-sale	0	0
Originations and repayments of loans held-for-investment and other	(960)	0
Purchases of operating lease assets	0	0
Disposals of operating lease assets	0	0
Capital contributions to subsidiaries	83	128
Returns of contributed capital	(645)	(223)
Increase (Decrease) in Restricted Cash	(3)	0
Increase (Decrease) in Non marketable equity securities	0	0
Payments for (Proceeds from) Other Investing Activities	(91)	0
Net cash provided by investing activities	(3,194)	(734)
Proceeds from (Repayments of) Short-term Debt	0	0
Increase (Decrease) in Deposits	0	0
Proceeds from issuance of long-term debt	962	0
Repayments of long-term debt	0	0
Net Change in Debt, Intercompany	1,349	752
Payments for Repurchase of Common Stock	0	0
Payments of Dividends	0	0
Dividends paid and returns of contributed capital, Intercompany	686	705
Capital contributions from parent	(83)	(128)
Net cash (used in) provided by financing activities	2,914	1,329
Effect of exchange-rate changes on cash and cash equivalents	0	0
Cash and Cash Equivalents, Period Increase (Decrease)	(240)	113
Cash and Cash Equivalents, at Carrying Value	(401)	(850)
Cash and Cash Equivalents, at Carrying Value	(641)	(737)
Consolidation, Eliminations [Member] | Affiliated Entity [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Payments for (Proceeds from) Investments	262
Payments for (Proceeds from) Loans and Leases	$ (1,316)	$ (639)

Contingencies and Other Risks (

Contingencies and Other Risks (Details) $ in Millions	51 Months Ended
	Mar. 31, 2017USD ($)
Loss Contingency [Abstract]
Consent Order Fees and Expenses	$ 240

Subsequent Events (Details)

Subsequent Events (Details) - $ / shares	Apr. 14, 2017	Mar. 31, 2017	Oct. 18, 2016	Jul. 18, 2016
Subsequent Event [Line Items]
Dividends Payable, Amount Per Share		$ 0.08	$ 0.08	$ 0.08
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends Payable, Amount Per Share	$ 0.08