Ally Financial (ALLY) 10-Q 31 Jul 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	6 Months Ended
	Jun. 30, 2017	Jul. 27, 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	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		449,853,338
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 8,257,669,855

Condensed Consolidated Statemen

Condensed Consolidated Statement of Income Condensed Consolidated Statement of Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Financing Revenue and Other Income [Line Items]
Interest and Fee Income, Loans and Leases	$ 1,447	$ 1,265	$ 2,815	$ 2,500
Interest and Dividend Income, Securities, Operating, Available-for-sale	146	99	280	201
Interest Income, Deposits with Financial Institutions	7	4	12	7
Operating Leases, Income Statement, Lease Revenue	488	701	1,031	1,470
Total financing revenue and other interest income	2,088	2,069	4,138	4,178
Interest Expense [Abstract]
Interest Expense, Deposits	250	203	481	396
Interest Expense, Short-term Borrowings	33	12	60	25
Interest Expense, Long-term Debt	417	436	841	878
Interest Expense	700	651	1,382	1,299
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	321	434	710	944
Net Financing Revenue	1,067	984	2,046	1,935
Other revenue [Abstract]
Insurance Services Revenue	227	236	468	466
Gain (Loss) on Sales of Loans, Net	36	3	50	4
Gain (Loss) on Extinguishment of Debt	(1)	0	(2)	(4)
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	23	39	50	93
Noninterest Income, Other Operating Income	103	96	218	191
Nonoperating Income (Expense)	388	374	784	750
Revenues	1,455	1,358	2,830	2,685
Provision for Loan Losses Expensed	269	172	540	392
Noninterest Expense [Abstract]
Labor and Related Expense	265	242	550	494
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	125	145	213	218
Other Noninterest Expense	420	386	825	771
Noninterest Expense	810	773	1,588	1,483
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	376	413	702	810
Income Tax Expense (Benefit)	122	56	235	206
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	254	357	467	604
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	(2)	3	(1)	6
Net Income (Loss) Attributable to Parent	252	360	466	610
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	76	120	96	266
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 328	$ 480	$ 562	$ 876
Earnings Per Share, Basic [Abstract]
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.55	$ 0.70	$ 1.01	$ 1.18
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	(0.01)	0.01	0	0.01
Earnings Per Share, Basic	0.55	0.71	1.01	1.20
Earnings Per Share, Diluted [Abstract]
Income (Loss) from Continuing Operations, Per Diluted Share	0.55	0.70	1.01	1.18
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	(0.01)	0.01	0	0.01
Earnings Per Share, Diluted	0.55	0.71	1.01	1.19
Common Stock, Dividends, Per Share, Declared	$ 0.08	$ 0	$ 0.16	$ 0
Retained Earnings [Member]
Net Income (Loss) Attributable to Parent	$ 252	$ 360	$ 466	$ 610

Condensed Consolidated Balance

Condensed Consolidated Balance Sheet & Mini Balance Sheet - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Assets [Abstract]
Cash and Due from Banks	$ 1,514	$ 1,547
Interest-bearing Deposits in Banks and Other Financial Institutions	2,863	4,387
Cash and Cash Equivalents, at Carrying Value	4,377	5,934
Available-for-sale securities	21,764	18,926
Held-to-maturity securities	1,189	839
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	17	0
Finance receivables and loans, net [Abstract]
Loans and Leases Receivable, Gross	120,528	118,944
Financing Receivable, Allowance for Credit Losses	1,225	1,144
Loans and Leases Receivable, Net Amount	119,303	117,800
Property Subject to or Available for Operating Lease, Net	9,717	11,470
Premiums receivable and other insurance assets	2,025	1,905
Other Assets	5,953	6,854
Assets	164,345	163,728
Liabilities and Equity [Abstract]
Noninterest-bearing deposit liabilities	107	84
Interest-bearing Deposit Liabilities	86,076	78,938
Deposits	86,183	79,022
Short-term Debt	10,712	12,673
Long-term Debt	49,145	54,128
Interest payable	399	351
Unearned Premiums	2,541	2,500
Accounts Payable and Accrued Liabilities	1,892	1,737
Liabilities	150,872	150,411
Equity [Abstract]
Common Stocks, Including Additional Paid in Capital, Net of Discount	21,208	21,166
Retained Earnings (Accumulated Deficit)	(6,760)	(7,151)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(245)	(341)
Treasury stock, Value	(730)	(357)
Stockholders' Equity Attributable to Parent, Total	13,473	13,317
Liabilities and Equity	164,345	163,728
Variable Interest Entity, Primary Beneficiary [Member]
Finance receivables and loans, net [Abstract]
Loans and Leases Receivable, Gross	22,035	24,630
Financing Receivable, Allowance for Credit Losses	140	173
Loans and Leases Receivable, Net Amount	21,895	24,457
Property Subject to or Available for Operating Lease, Net	907	1,745
Other Assets	827	1,390
Assets	23,629	27,592
Liabilities and Equity [Abstract]
Long-term Debt	12,499	13,259
Accounts Payable and Accrued Liabilities	12	12
Liabilities	$ 12,511	$ 13,271

Condensed Consolidated Balance4

Condensed Consolidated Balance Sheet and Mini Balance Sheet (Paranthetical) - USD ($) $ in Millions	Jun. 30, 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	489,581,850	485,707,644
Common Stock, Shares, Outstanding	452,291,918	467,000,306
Treasury Stock, Shares	37,289,932	18,707,338
Held-to-maturity Securities, Fair Value	$ 1,156	$ 789

Condensed Consolidated Stateme5

Condensed 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]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	610			610
Dividends, Preferred Stock, Cash	(30)			(30)
Stock Repurchased During Period, Value	(696)		(696)
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	36	36
Other Comprehensive Income (Loss), Net of Tax					266
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	266
Treasury Stock, Value, Acquired, Cost Method	(14)					(14)
Stockholders' Equity Attributable to Parent at Jun. 30, 2016	$ 13,611	21,136	0	(7,530)		(30)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Declared	$ 0
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ 35				35
Treasury Stock, Value, Acquired, Cost Method	(699)
Stockholders' Equity Attributable to Parent at Jun. 30, 2017	13,473	21,208	0	(6,760)		(730)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	466			466
Dividends, Preferred Stock, Cash	0
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	42	42
Other Comprehensive Income (Loss), Net of Tax					96
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	96
Treasury Stock, Value, Acquired, Cost Method	(373)					(373)
Dividends, Common Stock, Cash	(75)			(75)
Stockholders' Equity Attributable to Parent at Jun. 30, 2017	$ 13,473	$ 21,208	$ 0	$ (6,760)		$ (730)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Declared	$ 0.16
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (245)				$ (245)

Condensed Consolidated Stateme6

Condensed Consolidated Statement of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Income (Loss) Attributable to Parent	$ 466	$ 610
Depreciation, Amortization and Accretion, Net	1,003	1,241
Provision for Loan Losses Expensed Including Discontinued Operations	540	392
Gain Loss on Sales of Loans Net Including Discontinued Operations	50	4
Availableforsale Securities Gross Realized Gain Loss Excluding Otti Including Disc Ops	(50)	(93)
Gain (Loss) on Extinguishment of Debt	(2)	(4)
Payments for Origination and Purchases of Loans Held-for-sale	202	44
Proceeds from Sale of Loans Held-for-sale	187	144
Increase (Decrease) in Deferred Income Taxes	(203)	(193)
Increase (Decrease) in Interest Payable, Net	48	76
Increase (Decrease) in Other Operating Assets	94	(17)
Increase (Decrease) in Other Operating Liabilities	(50)	(55)
Increase (Decrease) in Other Operating Assets and Liabilities, Net	(67)	45
Net Cash Provided by (Used in) Operating Activities	2,070	2,436
Net Cash (Used in) Provided by Investing Activities [Abstract]
Payments to Acquire Available-for-sale Securities	(5,853)	(8,657)
Proceeds from sales of available-for-sale securities	2,162	6,584
Proceeds from maturities and repayment of available-for-sale securities	1,230	1,536
Payments to Acquire Held-to-maturity Securities	(313)	(571)
Proceeds from Sale and Maturity of Held-to-maturity Securities	17	0
Payments for (Proceeds from) Loans and Leases	(1,817)	(2,442)
Proceeds from Sale of Loans Held-for-investment	1,280	4,156
Originations and repayments of loans held-for-investment and other	1,588	3,211
Purchases of operating lease assets	(1,965)	(1,472)
Disposals of operating lease assets	3,043	3,047
Payments to Acquire Interest in Subsidiaries and Affiliates	0	288
Increase (Decrease) in Restricted Cash	474	482
Increase (Decrease) in Non marketable equity securities	107	(354)
Payments for (Proceeds from) Other Investing Activities	(93)	(69)
Net cash provided by investing activities	(3,316)	(1,259)
Net Cash Used in Financing Activities [Abstract]
Proceeds from (Repayments of) Short-term Debt	(1,962)	(2,112)
Increase (Decrease) in Deposits	7,133	6,308
Proceeds from issuance of long-term debt	9,330	9,020
Repayments of long-term debt	(14,366)	(14,305)
Payments for Repurchase of Preferred Stock and Preference Stock	0	696
Payments for Repurchase of Common Stock	(373)	(14)
Payments of Dividends	(75)	(30)
Net cash (used in) provided by financing activities	(313)	(1,829)
Effect of exchange-rate changes on cash and cash equivalents	2	3
Cash and Cash Equivalents, Period Increase (Decrease)	(1,557)	(649)
Cash and Cash Equivalents, at Carrying Value	5,934	6,380
Cash and Cash Equivalents, at Carrying Value	4,377	5,731
Supplemental Cash Flow Information [Abstract]
Interest Paid	1,331	1,234
Income Taxes Paid	28	12
Held-to-maturity securities received in consideration for loans sold	56	0
Transfer of Portfolio Loans and Leases to Held-for-sale	1,298	4,174
Proceeds from sales and repayments of mortgage loans held-for-investment originally designated as held-for-sale	$ 20	$ 18

Description of Business, Basis

Description of Business, Basis of Presentation, and Changes in Significant Accounting Policies	6 Months Ended
	Jun. 30, 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 through Ally Home, and wealth management solutions through Ally Invest. 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 June 30, 2017 , and for the three months and six months ended June 30, 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 VIE. 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 . This note was updated to address the Dodd-Frank Act risk retention rules and differs from our description in Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K. 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 changed several aspects of share-based payment accounting. The amendments allowed 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 modified 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 required that all excess tax benefits and tax deficiencies related to share-based payment awards 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 addressed 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 six months ended June 30, 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 core 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 retrospective 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, revenue on certain noninsurance contracts, brokering commissions through our insurance operations, sales of other real estate owned, sales of repossessed and off-lease vehicles, remarketing fee income through SmartAuction, and fee income generated through Ally Invest. 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 and expense upon the origination of the contract and the immediate recognition of certain expenses upon the origination of the contract that are currently deferred. Our assessment is not final; however, we do not expect the impact of the new guidance to these specific contracts to be material to the financial statements. We currently plan to adopt this guidance as of January 1, 2018, and expect to use 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. We currently plan to adopt these amendments on January 1, 2018, and expect 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 operating leases and sales type and direct financing leases (sales type and direct financing leases were both 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. We currently plan to adopt these amendments on January 1, 2019, and expect 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. We are in the process of designing and building the models and procedures that will be used to calculate the credit loss reserves in accordance with these amendments. We currently plan to adopt these amendments on January 1, 2020, and expect 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. The amendments will not impact financial results, but will result in a change in the presentation of restricted cash and restricted cash equivalents within the statement of cash flows. We currently plan to adopt these amendments on January 1, 2018, and expect to use the retrospective approach as required. 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. We currently plan to adopt these amendments on January 1, 2019, and expect to use the modified retrospective approach as required.

Acquisitions Acquisitions

Acquisitions Acquisitions	6 Months Ended
	Jun. 30, 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 $298 million in cash. TradeKing, which has been rebranded as Ally Invest, operates as a wholly-owned subsidiary of Ally Financial Inc. The addition of brokerage and wealth management is a natural extension of our online banking franchise, creating a full suite of financial products for savings and investments. We applied the acquisition method of accounting to this transaction, which generally requires the initial recognition of assets acquired, including identifiable intangible assets, and liabilities assumed at their respective fair value. Goodwill is recognized as the excess of the acquisition price after the recognition of the net assets, including the identifiable intangible assets. Beginning in June 2016, financial information related to Ally Invest is included within Corporate and Other. The following table summarizes the allocation of cash consideration paid for TradeKing and the amounts of the identifiable assets acquired and liabilities assumed recognized at the acquisition date. ($ 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 $2 million and $5 million of amortization on these intangible assets during the three months and six months ended June 30, 2017 , respectively. (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 which we rebranded as Clearlane, 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	6 Months Ended
	Jun. 30, 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 June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Pretax (loss) income $ (2 ) $ (2 ) $ (1 ) $ 2 Tax benefit — (5 ) — (4 )

Other Income, Net of Losses

Other Income, Net of Losses	6 Months Ended
	Jun. 30, 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 June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Remarketing fees $ 27 $ 25 $ 56 $ 53 Late charges and other administrative fees 25 22 52 47 Servicing fees 14 18 30 31 Income from equity-method investments 5 5 5 11 Other, net 32 26 75 49 Total other income, net of losses $ 103 $ 96 $ 218 $ 191

Reserves for Insurance Losses a

Reserves for Insurance Losses and Loss Adjustment Expenses Reserves for Insurance Losses and Loss Adjustment Expenses	6 Months Ended
	Jun. 30, 2017
Reserves for Insurance Losses and Loss 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 211 221 Prior years (a) 2 (3 ) Total net insurance losses and loss adjustment expenses incurred 213 218 Net insurance losses and loss adjustment expenses paid or payable related to: Current year (183 ) (184 ) Prior years (27 ) (25 ) Total net insurance losses and loss adjustment expenses paid or payable (210 ) (209 ) Net reserves for insurance losses and loss adjustment expenses at June 30, 44 58 Plus: Reinsurance recoverable 135 106 Total gross reserves for insurance losses and loss adjustment expenses at June 30, $ 179 $ 164 (a) There have been no material adverse changes to the reserve for prior years.

Other Operating Expenses

Other Operating Expenses	6 Months Ended
	Jun. 30, 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 June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Insurance commissions $ 104 $ 97 $ 203 $ 191 Technology and communications 71 67 140 133 Lease and loan administration 39 34 75 66 Advertising and marketing 33 21 63 48 Regulatory and licensing fees 28 21 55 42 Vehicle remarketing and repossession 25 22 53 46 Professional services 27 26 53 50 Premises and equipment depreciation 23 21 45 42 Occupancy 11 12 23 25 Non-income taxes 8 8 16 17 Other 51 57 99 111 Total other operating expenses $ 420 $ 386 $ 825 $ 771

Investment Securities

Investment Securities	6 Months Ended
	Jun. 30, 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. June 30, 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 $ 1,891 $ — $ (39 ) $ 1,852 $ 1,680 $ — $ (60 ) $ 1,620 U.S. States and political subdivisions 780 13 (11 ) 782 794 7 (19 ) 782 Foreign government 148 2 — 150 157 5 — 162 Agency mortgage-backed residential 13,809 39 (172 ) 13,676 10,473 29 (212 ) 10,290 Mortgage-backed residential 2,063 11 (36 ) 2,038 2,162 5 (70 ) 2,097 Mortgage-backed commercial 474 2 (1 ) 475 537 2 (2 ) 537 Asset-backed 1,010 6 (2 ) 1,014 1,396 6 (2 ) 1,400 Corporate debt 1,273 8 (9 ) 1,272 1,452 7 (16 ) 1,443 Total debt securities (a) (b) 21,448 81 (270 ) 21,259 18,651 61 (381 ) 18,331 Equity securities 549 9 (53 ) 505 642 7 (54 ) 595 Total available-for-sale securities $ 21,997 $ 90 $ (323 ) $ 21,764 $ 19,293 $ 68 $ (435 ) $ 18,926 Held-to-maturity securities Debt securities Agency mortgage-backed residential (c) $ 1,143 $ 2 $ (35 ) $ 1,110 $ 839 $ — $ (50 ) $ 789 Asset-backed retained notes 46 — — 46 — — — — Total held-to-maturity securities $ 1,189 $ 2 $ (35 ) $ 1,156 $ 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 June 30, 2017 , and December 31, 2016 , respectively. (b) Investment securities with a fair value of $3,316 million and $4,881 million at June 30, 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 $1,420 million and $737 million of the underlying investment securities at June 30, 2017 , and December 31, 2016 , respectively. (c) Agency mortgage-backed residential debt securities are held for liquidity purposes. Securities with a fair value of $0 million and $87 million at June 30, 2017 , and December 31, 2016 , respectively, were pledged to secure advances from the FHLB. The maturity distribution of investment securities outstanding is summarized in the following tables. Call or prepayment options may cause actual maturities to differ from contractual maturities. Total Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years ($ in millions) Amount Yield Amount Yield Amount Yield Amount Yield Amount Yield June 30, 2017 Fair value of available-for-sale debt securities (a) U.S. Treasury $ 1,852 1.7 % $ — — % $ 21 1.7 % $ 1,831 1.7 % $ — — % U.S. States and political subdivisions 782 3.1 38 2.5 45 2.4 165 2.8 534 3.3 Foreign government 150 2.5 — — 68 2.6 82 2.4 — — Agency mortgage-backed residential 13,676 3.0 — — — — 3 2.9 13,673 3.0 Mortgage-backed residential 2,038 2.9 — — — — — — 2,038 2.9 Mortgage-backed commercial 475 3.1 — — — — 3 2.9 472 3.1 Asset-backed 1,014 2.9 — — 801 3.0 57 2.9 156 2.7 Corporate debt 1,272 2.9 125 2.3 617 2.6 496 3.2 34 5.2 Total available-for-sale debt securities $ 21,259 2.9 $ 163 2.3 $ 1,552 2.8 $ 2,637 2.1 $ 16,907 3.0 Amortized cost of available-for-sale debt securities $ 21,448 $ 163 $ 1,545 $ 2,675 $ 17,065 Amortized cost of held-to-maturity securities Agency mortgage-backed residential $ 1,143 3.0 % $ — — % $ — — % $ — — % $ 1,143 3.0 % Asset-backed retained notes 46 1.6 4 0.8 41 1.6 1 3.0 — — Total held-to-maturity securities $ 1,189 2.9 $ 4 0.8 $ 41 1.6 $ 1 3.0 $ 1,143 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 (b) $ 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. (b) Our held-to-maturity securities portfolio as of December 31, 2016, consisted of agency mortgage-backed residential debt securities. The balances of cash equivalents were $1.2 billion and $291 million at June 30, 2017 , and December 31, 2016 , respectively, and were composed primarily of money market accounts and short-term securities, including U.S. Treasury bills. The following table presents interest and dividends on investment securities. Three months ended June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Taxable interest $ 130 $ 89 $ 249 $ 183 Taxable dividends 3 5 5 9 Interest and dividends exempt from U.S. federal income tax 6 5 11 9 Interest and dividends on investment securities $ 139 $ 99 $ 265 $ 201 The following table presents gross gains and losses realized upon the sales of available-for-sale securities. There were no other-than-temporary impairments upon the sales of available-for-sale securities for either period. Three months ended June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Gross realized gains $ 24 $ 40 $ 51 $ 94 Gross realized losses (a) (1 ) (1 ) (1 ) (1 ) Other gain on investments, net $ 23 $ 39 $ 50 $ 93 (a) Certain available-for-sale securities were sold at a loss in 2017 and 2016 as a result of market conditions within these respective periods (e.g., a downgrade in the rating of a debt security). Any such sales were made in accordance with our risk management policies and practices. 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 June 30, 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 June 30, 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 June 30, 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. June 30, 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 $ 1,829 $ (39 ) $ — $ — $ 1,612 $ (60 ) $ — $ — U.S. States and political subdivisions 401 (10 ) 15 (1 ) 524 (19 ) — — Foreign government 26 — — — 38 — — — Agency mortgage-backed residential 9,293 (162 ) 448 (10 ) 8,052 (196 ) 587 (16 ) Mortgage-backed residential 410 (6 ) 763 (30 ) 813 (17 ) 860 (53 ) Mortgage-backed commercial 102 (1 ) 49 — 47 (1 ) 149 (1 ) Asset-backed 293 (1 ) 107 (1 ) 375 (2 ) 127 — Corporate debt 495 (7 ) 36 (2 ) 744 (14 ) 46 (2 ) Total temporarily impaired debt securities 12,849 (226 ) 1,418 (44 ) 12,205 (309 ) 1,769 (72 ) Temporarily impaired equity securities 140 (9 ) 124 (44 ) 151 (8 ) 269 (46 ) Total temporarily impaired available-for-sale securities $ 12,989 $ (235 ) $ 1,542 $ (88 ) $ 12,356 $ (317 ) $ 2,038 $ (118 )

Finance Receivables and Loans,

Finance Receivables and Loans, Net	6 Months Ended
	Jun. 30, 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) June 30, 2017 December 31, 2016 Consumer automotive (a) $ 66,774 $ 65,793 Consumer mortgage Mortgage Finance (b) 8,866 8,294 Mortgage — Legacy (c) 2,428 2,756 Total consumer mortgage 11,294 11,050 Total consumer 78,068 76,843 Commercial Commercial and industrial Automotive 34,782 35,041 Other 3,620 3,248 Commercial real estate — Automotive 4,058 3,812 Total commercial 42,460 42,101 Total finance receivables and loans (d) $ 120,528 $ 118,944 (a) Includes $28 million and $43 million of fair value adjustment for loans in hedge accounting relationships at June 30, 2017 , and December 31, 2016 , respectively. Refer to Note 19 for additional information. (b) Includes loans originated as interest-only mortgage loans of $24 million and $30 million at June 30, 2017 , and December 31, 2016 , respectively, 3% of which are expected to start principal amortization in 2017 , none in 2018 , 34% in 2019 , 43% in 2020 , and none thereafter. (c) Includes loans originated as interest-only mortgage loans of $587 million and $714 million at June 30, 2017 , and December 31, 2016 , respectively, 7% 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 $439 million and $359 million at June 30, 2017 , and December 31, 2016 , respectively, for unearned income, unamortized premiums and discounts, and deferred fees and costs. The following tables present an analysis of the activity in the allowance for loan losses on finance receivables and loans. Three months ended June 30, 2017 ($ in millions) Consumer automotive Consumer mortgage Commercial Total Allowance at April 1, 2017 $ 941 $ 86 $ 128 $ 1,155 Charge-offs (a) (290 ) (6 ) — (296 ) Recoveries 91 6 — 97 Net charge-offs (199 ) — — (199 ) Provision for loan losses 260 (3 ) 12 269 Allowance at June 30, 2017 $ 1,002 $ 83 $ 140 $ 1,225 (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. Three months ended June 30, 2016 ($ in millions) Consumer automotive Consumer mortgage Commercial Total Allowance at April 1, 2016 $ 850 $ 115 $ 112 $ 1,077 Charge-offs (a) (227 ) (9 ) (1 ) (237 ) Recoveries 79 5 1 85 Net charge-offs (148 ) (4 ) — (152 ) Provision for loan losses 168 (2 ) 6 172 Other (b) (8 ) — — (8 ) Allowance at June 30, 2016 $ 862 $ 109 $ 118 $ 1,089 (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. Six months ended June 30, 2017 ($ in millions) Consumer automotive Consumer mortgage Commercial Total Allowance at January 1, 2017 $ 932 $ 91 $ 121 $ 1,144 Charge-offs (a) (631 ) (15 ) — (646 ) Recoveries 181 13 — 194 Net charge-offs (450 ) (2 ) — (452 ) Provision for loan losses 527 (6 ) 19 540 Other (b) (7 ) — — (7 ) Allowance at June 30, 2017 $ 1,002 $ 83 $ 140 $ 1,225 Allowance for loan losses at June 30, 2017 Individually evaluated for impairment $ 34 $ 31 $ 32 $ 97 Collectively evaluated for impairment 968 52 108 1,128 Finance receivables and loans at gross carrying value Ending balance $ 66,774 $ 11,294 $ 42,460 $ 120,528 Individually evaluated for impairment 380 242 151 773 Collectively evaluated for impairment 66,394 11,052 42,309 119,755 (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. Six months ended June 30, 2016 ($ in millions) Consumer automotive Consumer mortgage Commercial Total Allowance at January 1, 2016 $ 834 $ 114 $ 106 $ 1,054 Charge-offs (a) (480 ) (19 ) (1 ) (500 ) Recoveries 159 9 1 169 Net charge-offs (321 ) (10 ) — (331 ) Provision for loan losses 375 5 12 392 Other (b) (26 ) — — (26 ) Allowance at June 30, 2016 $ 862 $ 109 $ 118 $ 1,089 Allowance for loan losses at June 30, 2016 Individually evaluated for impairment $ 26 $ 37 $ 23 $ 86 Collectively evaluated for impairment 836 72 95 1,003 Finance receivables and loans at gross carrying value Ending balance $ 63,281 $ 11,084 $ 38,288 $ 112,653 Individually evaluated for impairment 348 254 122 724 Collectively evaluated for impairment 62,933 10,830 38,166 111,929 (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 June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Consumer automotive $ 85 $ 1,560 $ 1,298 $ 4,159 Consumer mortgage 3 4 6 6 Commercial — 28 — 28 Total sales and transfers $ 88 $ 1,592 $ 1,304 $ 4,193 The following table presents information about significant purchases of finance receivables and loans. Three months ended June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Consumer automotive $ 611 $ — $ 679 $ — Consumer mortgage 809 1,018 1,136 2,388 Total purchases of finance receivables and loans $ 1,420 $ 1,018 $ 1,815 $ 2,388 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 June 30, 2017 Consumer automotive $ 1,569 $ 350 $ 236 $ 2,155 $ 64,619 $ 66,774 Consumer mortgage Mortgage Finance 32 3 6 41 8,825 8,866 Mortgage — Legacy 34 18 55 107 2,321 2,428 Total consumer mortgage 66 21 61 148 11,146 11,294 Total consumer 1,635 371 297 2,303 75,765 78,068 Commercial Commercial and industrial Automotive 18 — 8 26 34,756 34,782 Other — — — — 3,620 3,620 Commercial real estate — Automotive — — — — 4,058 4,058 Total commercial 18 — 8 26 42,434 42,460 Total consumer and commercial $ 1,653 $ 371 $ 305 $ 2,329 $ 118,199 $ 120,528 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) June 30, 2017 December 31, 2016 Consumer automotive $ 540 $ 598 Consumer mortgage Mortgage Finance 9 10 Mortgage — Legacy 83 89 Total consumer mortgage 92 99 Total consumer 632 697 Commercial Commercial and industrial Automotive 75 33 Other 69 84 Commercial real estate — Automotive 7 5 Total commercial 151 122 Total consumer and commercial finance receivables and loans $ 783 $ 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. June 30, 2017 December 31, 2016 ($ in millions) Performing Nonperforming Total Performing Nonperforming Total Consumer automotive $ 66,234 $ 540 $ 66,774 $ 65,195 $ 598 $ 65,793 Consumer mortgage Mortgage Finance 8,857 9 8,866 8,284 10 8,294 Mortgage — Legacy 2,345 83 2,428 2,667 89 2,756 Total consumer mortgage 11,202 92 11,294 10,951 99 11,050 Total consumer $ 77,436 $ 632 $ 78,068 $ 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. June 30, 2017 December 31, 2016 ($ in millions) Pass Criticized (a) Total Pass Criticized (a) Total Commercial and industrial Automotive $ 32,851 $ 1,931 $ 34,782 $ 33,160 $ 1,881 $ 35,041 Other 2,859 761 3,620 2,597 651 3,248 Commercial real estate — Automotive 3,906 152 4,058 3,653 159 3,812 Total commercial $ 39,616 $ 2,844 $ 42,460 $ 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 June 30, 2017 Consumer automotive $ 396 $ 380 $ 102 $ 278 $ 34 Consumer mortgage Mortgage Finance 8 8 4 4 — Mortgage — Legacy 238 234 55 179 31 Total consumer mortgage 246 242 59 183 31 Total consumer 642 622 161 461 65 Commercial Commercial and industrial Automotive 75 75 27 48 5 Other 78 69 10 59 26 Commercial real estate — Automotive 7 7 3 4 1 Total commercial 160 151 40 111 32 Total consumer and commercial finance receivables and loans $ 802 $ 773 $ 201 $ 572 $ 97 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 tables present average balance and interest income for our impaired finance receivables and loans. 2017 2016 Three months ended June 30, ($ in millions) Average balance Interest income Average balance Interest income Consumer automotive $ 391 $ 5 $ 341 $ 4 Consumer mortgage Mortgage Finance 8 — 8 — Mortgage — Legacy 238 3 251 3 Total consumer mortgage 246 3 259 3 Total consumer 637 8 600 7 Commercial Commercial and industrial Automotive 54 1 35 — Other 73 8 65 — Commercial real estate — Automotive 6 — 6 — Total commercial 133 9 106 — Total consumer and commercial finance receivables and loans $ 770 $ 17 $ 706 $ 7 2017 2016 Six months ended June 30, ($ in millions) Average balance Interest income Average balance Interest income Consumer automotive $ 381 $ 10 $ 335 $ 8 Consumer mortgage Mortgage Finance 8 — 8 — Mortgage — Legacy 239 5 253 5 Total consumer mortgage 247 5 261 5 Total consumer 628 15 596 13 Commercial Commercial and industrial Automotive 47 1 32 — Other 77 8 56 1 Commercial real estate — Automotive 6 — 7 — Total commercial 130 9 95 1 Total consumer and commercial finance receivables and loans $ 758 $ 24 $ 691 $ 14 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. These programs 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 $690 million and $663 million at June 30, 2017 , and December 31, 2016 , respectively. Commercial commitments to lend additional funds to borrowers whose terms had been modified in a TDR were $4 million and $2 million at June 30, 2017 , and December 31, 2016 , respectively. Refer to Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K for additional information. The following tables present information related to finance receivables and loans recorded at gross carrying value modified in connection with a TDR during the period. 2017 2016 Three months ended June 30, ($ 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 5,762 $ 103 $ 88 4,767 $ 79 $ 68 Consumer mortgage Mortgage Finance — — — 2 1 1 Mortgage — Legacy 19 3 2 26 4 4 Total consumer mortgage 19 3 2 28 5 5 Total consumer 5,781 106 90 4,795 84 73 Commercial Commercial and industrial Other 1 21 21 — — — Total commercial 1 21 21 — — — Total consumer and commercial finance receivables and loans 5,782 $ 127 $ 111 4,795 $ 84 $ 73 2017 2016 Six months ended June 30, ($ 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 12,209 $ 218 $ 187 10,389 $ 168 $ 144 Consumer mortgage Mortgage Finance 1 — — 3 2 2 Mortgage — Legacy 72 15 14 57 8 8 Total consumer mortgage 73 15 14 60 10 10 Total consumer 12,282 233 201 10,449 178 154 Commercial Commercial and industrial Other 2 44 44 — — — Total commercial 2 44 44 — — — Total consumer and commercial finance receivables and loans 12,284 $ 277 $ 245 10,449 $ 178 $ 154 The following tables present 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 June 30, ($ in millions) Number of loans Gross carrying value Charge-off amount Number of loans Gross carrying value Charge-off amount Consumer automotive 2,143 $ 25 $ 17 1,858 $ 23 $ 13 Consumer mortgage Mortgage Finance — — — — — — Mortgage — Legacy — — — 2 — — Total consumer finance receivables and loans 2,143 $ 25 $ 17 1,860 $ 23 $ 13 2017 2016 Six months ended June 30, ($ in millions) Number of loans Gross carrying value Charge-off amount Number of loans Gross carrying value Charge-off amount Consumer automotive 4,132 $ 49 $ 33 3,658 $ 46 $ 25 Consumer mortgage Mortgage Finance 1 1 — — — — Mortgage — Legacy — — — 3 — — Total consumer finance receivables and loans 4,133 $ 50 $ 33 3,661 $ 46 $ 25

Investment in Operating Leases,

Investment in Operating Leases, Net	6 Months Ended
	Jun. 30, 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) June 30, 2017 December 31, 2016 Vehicles $ 12,136 $ 14,584 Accumulated depreciation (2,419 ) (3,114 ) Investment in operating leases, net $ 9,717 $ 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 June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Depreciation expense on operating lease assets (excluding remarketing gains) $ 353 $ 520 $ 739 $ 1,085 Remarketing gains (32 ) (86 ) (29 ) (141 ) Net depreciation expense on operating lease assets $ 321 $ 434 $ 710 $ 944

Securitizations and Variable In

Securitizations and Variable Interest Entities	6 Months Ended
	Jun. 30, 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 a legal 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 $0 million and $2 million for the three months and six months ended June 30, 2017 , respectively. There were no pretax gains or losses for the three months and six months ended June 30, 2016 . We provide long-term guarantee contracts to investors in certain nonconsolidated affordable housing entities and have extended a line of credit to provide liquidity. Since we do not have control over the entities or the power to make decisions, we do not consolidate the entities and our involvement is limited to the guarantee and the line of credit. We have involvement with various other nonconsolidated equity investments, including affordable housing entities and venture capital funds and loan funds. We do not consolidate these entities and our involvement is limited to our outstanding investment, additional capital committed to these funds plus any previously recognized low income housing tax credits that are subject to recapture. Refer to Note 11 to the Consolidated Financial Statements included in our 2016 Annual Report on Form 10-K for further description of our securitization activities and our involvement with VIEs. The following table presents our involvement in consolidated and nonconsolidated VIEs in which we hold variable interests. For additional detail related to the assets and liabilities of consolidated variable interest entities refer to the Condensed Consolidated Balance Sheet. ($ in millions) Carrying value of total assets Carrying value of total liabilities Assets sold to nonconsolidated VIEs (a) Maximum exposure to loss in nonconsolidated VIEs June 30, 2017 On-balance sheet variable interest entities Consumer automotive $ 18,495 (b) $ 7,941 (c) Commercial automotive 14,052 4,657 Off-balance sheet variable interest entities Consumer automotive 48 (d) — $ 2,662 $ 2,710 (e) Commercial other 539 (f) 229 (g) — 719 (h) Total $ 33,134 $ 12,827 $ 2,662 $ 3,429 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 $9.0 billion and $9.6 billion of assets that are not encumbered by VIE beneficial interests held by third parties at June 30, 2017 , and December 31, 2016 , respectively. Ally or consolidated affiliates hold the interests in these assets, which eliminate in consolidation. (c) Includes $87 million and $50 million of liabilities due to consolidated affiliates at June 30, 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 $46 million classified as held-to-maturity securities and $2 million classified as other assets at June 30, 2017 . Of the total amount at June 30, 2017 , $48 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 six months ended June 30, 2017 , and 2016 . Additionally, this table contains information regarding cash flows received from and paid to nonconsolidated securitization entities that existed during each period. Six months ended June 30, ($ in millions) Consumer automotive 2017 Cash proceeds from transfers completed during the period $ 1,187 Cash disbursements for repurchases during the period (a) (491 ) Servicing fees 18 Cash flows received on retained interests in securitization entities 10 Other cash flows 4 2016 Cash proceeds from transfers completed during the period $ 1,604 Servicing fees 17 Other cash flows 5 (a) During the second quarter of 2017, we elected to not renew a retail automotive credit conduit facility and also purchased the related retail automotive loans and settled associated retained interests. 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 past due ($ in millions) June 30, 2017 December 31, 2016 June 30, 2017 December 31, 2016 On-balance sheet loans Consumer automotive $ 66,774 $ 65,793 $ 586 $ 730 Consumer mortgage 11,297 11,050 82 85 Commercial automotive 38,840 38,853 8 7 Commercial other 3,634 3,248 — — Total on-balance sheet loans 120,545 118,944 676 822 Off-balance sheet securitization entities Consumer automotive 2,662 2,392 13 13 Total off-balance sheet securitization entities 2,662 2,392 13 13 Whole-loan sales (a) 1,947 3,164 3 6 Total $ 125,154 $ 124,500 $ 692 $ 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 June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 On-balance sheet loans Consumer automotive $ 199 $ 148 $ 450 $ 321 Consumer mortgage — 4 2 10 Total on-balance sheet loans 199 152 452 331 Off-balance sheet securitization entities Consumer automotive 3 2 6 4 Total off-balance sheet securitization entities 3 2 6 4 Whole-loan sales (a) 1 1 2 1 Total $ 203 $ 155 $ 460 $ 336 (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	6 Months Ended
	Jun. 30, 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 $14 million and $30 million during the three months and six months ended June 30, 2017 , respectively, compared to $18 million and $31 million during the three months and six months ended June 30, 2016 . Automotive Finance Serviced Assets The current unpaid principal balance and any related unamortized deferred fees and costs of total serviced automotive finance loans and leases outstanding were as follows. ($ in millions) June 30, 2017 December 31, 2016 On-balance sheet automotive finance loans and leases Consumer automotive $ 66,491 $ 65,646 Commercial automotive 38,840 38,853 Operating leases 9,615 11,311 Other 67 67 Off-balance sheet automotive finance loans Securitizations 2,690 2,412 Whole-loan sales 1,964 3,191 Total serviced automotive finance loans and leases $ 119,667 $ 121,480

Other Assets

Other Assets	6 Months Ended
	Jun. 30, 2017
Other Assets [Abstract]
Other Assets Disclosure [Text Block]	Other Assets The components of other assets were as follows. ($ in millions) June 30, 2017 December 31, 2016 Property and equipment at cost $ 985 $ 901 Accumulated depreciation (565 ) (525 ) Net property and equipment 420 376 Restricted cash collections for securitization trusts (a) 1,259 1,694 Nonmarketable equity investments (b) 938 1,046 Net deferred tax assets 764 994 Accrued interest and rent receivables 470 476 Goodwill (c) 240 240 Cash reserve deposits held for securitization trusts (d) 143 184 Other accounts receivable 115 100 Restricted cash and cash equivalents 113 111 Cash collateral placed with counterparties 103 167 Fair value of derivative contracts in receivable position (e) 41 95 Other assets 1,347 1,371 Total other assets $ 5,953 $ 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 $454 million and $577 million at June 30, 2017 , and December 31, 2016 , respectively; and Federal Reserve Bank (FRB) stock of $444 million and $435 million at June 30, 2017 , and December 31, 2016 , respectively. (c) Includes goodwill of $27 million at our Insurance operations at both June 30, 2017 , and December 31, 2016 ; $193 million within Corporate and Other at both June 30, 2017 , and December 31, 2016 ; and $20 million within Automotive Finance operations at both June 30, 2017 , and December 31, 2016 . No changes to the carrying amount of goodwill were recorded during the six months ended June 30, 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	6 Months Ended
	Jun. 30, 2017
Deposits [Abstract]
Deposit Liabilities Disclosures [Text Block]	Deposit Liabilities Deposit liabilities consisted of the following. ( $ in millions ) June 30, 2017 December 31, 2016 Noninterest-bearing deposits $ 107 $ 84 Interest-bearing deposits Savings and money market checking accounts 50,732 46,976 Certificates of deposit 35,299 31,795 Dealer deposits 45 167 Total deposit liabilities $ 86,183 $ 79,022 At June 30, 2017 , and December 31, 2016 , certificates of deposit included $13.2 billion and $12.1 billion , respectively, of certificates of deposit in denominations of $100 thousand or more. At June 30, 2017 , and December 31, 2016 , certificates of deposit included $3.7 billion and $3.5 billion , respectively, in denominations in excess of $250 thousand federal insurance limits.

Debt

Debt	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
Debt Disclosure [Text Block]	Debt Short-term Borrowings The following table presents the composition of our short-term borrowings portfolio. June 30, 2017 December 31, 2016 ($ in millions) Unsecured Secured (a) Total Unsecured Secured (a) Total Demand notes $ 3,457 $ — $ 3,457 $ 3,622 $ — $ 3,622 Federal Home Loan Bank — 4,300 4,300 — 7,875 7,875 Financial instruments sold under agreements to repurchase — 1,706 1,706 — 1,176 1,176 Other 1,249 (b) — 1,249 — — — Total short-term borrowings $ 4,706 $ 6,006 $ 10,712 $ 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 June 30, 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 June 30, 2017 , the financial instruments sold under agreements to repurchase consisted of $139 million of U.S. Treasury securities set to mature within the next 30 days, and agency mortgage-backed residential debt securities set to mature as follows: $652 million within the next 30 days , $348 million within 31 to 60 days, and $183 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 initially set to mature by July 2017 in exchange for $500 million , which was recorded as a short-term secured borrowing. As of June 30, 2017 , the balance was $384 million . In July 2017, we extended the maturity of this repurchase agreement to March 2018. 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 June 30, 2017 , we placed cash collateral totaling $11 million with counterparties under these collateral arrangements associated with our repurchase agreements. Long-term Debt The following table presents the composition of our long-term debt portfolio. June 30, 2017 December 31, 2016 ($ in millions) Unsecured Secured Total Unsecured Secured Total Long-term debt Due within one year $ 3,342 $ 8,402 $ 11,744 $ 4,274 $ 10,279 $ 14,553 Due after one year (a) 13,909 23,192 37,101 15,450 23,810 39,260 Fair value adjustment (b) 309 (9 ) 300 326 (11 ) 315 Total long-term debt (c) $ 17,560 $ 31,585 $ 49,145 $ 20,050 $ 34,078 $ 54,128 (a) Includes $2.6 billion of trust preferred securities at both June 30, 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 $6.5 billion and $6.1 billion at June 30, 2017 , and December 31, 2016 , respectively. The following table presents the scheduled remaining maturity of long-term debt at June 30, 2017 , assuming no early redemptions will occur. The actual payment of secured debt may vary based on the payment activity of the related pledged assets. ($ in millions) 2017 2018 2019 2020 2021 2022 and thereafter Fair value adjustment Total Unsecured Long-term debt $ 1,792 $ 3,700 $ 1,681 $ 2,249 $ 638 $ 8,473 $ 309 $ 18,842 Original issue discount (47 ) (100 ) (39 ) (39 ) (43 ) (1,014 ) — (1,282 ) Total unsecured 1,745 3,600 1,642 2,210 595 7,459 309 17,560 Secured Long-term debt 4,824 7,928 8,610 6,109 2,566 1,557 (9 ) 31,585 Total long-term debt $ 6,569 $ 11,528 $ 10,252 $ 8,319 $ 3,161 $ 9,016 $ 300 $ 49,145 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. June 30, 2017 December 31, 2016 ($ in millions) Total (a) Ally Bank Total (a) Ally Bank Investment securities (b) $ 3,260 $ 1,896 $ 4,895 $ 4,231 Mortgage assets held-for-investment and lending receivables 11,193 11,193 10,954 10,954 Consumer automotive finance receivables (b) 25,658 4,421 27,846 5,751 Commercial automotive finance receivables 17,883 17,733 19,487 19,280 Investment in operating leases, net 956 28 2,040 913 Total assets restricted as collateral (c) (d) $ 58,950 $ 35,271 $ 65,222 $ 41,129 Secured debt $ 37,591 (e) $ 17,194 $ 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 $17.1 billion and $19.0 billion at June 30, 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 FRB Discount Window. Ally Bank had assets pledged and restricted as collateral to the FRB totaling $2.4 billion at both June 30, 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 $6.0 billion and $9.1 billion of short-term borrowings at June 30, 2017 , and December 31, 2016 , respectively. Trust Preferred Securities At June 30, 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 June 30, 2017 , Ally Bank had exclusive access to $2.0 billion of funding capacity from committed credit facilities. Funding programs supported by the FRB and the FHLB 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 June 30, 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 June 30, 2017 , we had $2.6 billion of committed funding capacity from revolving facilities with a remaining tenor greater than 364 days. Committed Funding Facilities Outstanding Unused capacity (a) Total capacity ($ in millions) June 30, 2017 December 31, 2016 June 30, 2017 December 31, 2016 June 30, 2017 December 31, 2016 Bank funding Secured (b) $ 1,750 $ 3,250 $ 250 $ 350 $ 2,000 $ 3,600 Parent funding Secured 10,880 11,550 2,295 1,975 13,175 13,525 Unsecured 1,250 — — 1,250 1,250 1,250 Total committed facilities $ 13,880 $ 14,800 $ 2,545 $ 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 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	6 Months Ended
	Jun. 30, 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 ) June 30, 2017 December 31, 2016 Accounts payable $ 871 $ 649 Employee compensation and benefits 182 232 Reserves for insurance losses and loss adjustment expenses 179 149 Fair value of derivative contracts in payable position (a) 43 95 Deferred revenue 40 56 Cash collateral received from counterparties 6 10 Other liabilities 571 546 Total accrued expenses and other liabilities $ 1,892 $ 1,737 (a) For additional information on derivative instruments and hedging activities, refer to Note 19 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive (Loss) Income	6 Months Ended
	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Abstract]
Comprehensive Income (Loss) Note [Text Block]	Accumulated Other Comprehensive (Loss) Income The following table presents changes, net of tax, in each component of accumulated other comprehensive (loss) income. ($ in millions) Unrealized gains on investment securities (a) Translation adjustments and net investment hedges (b) Cash flow hedges (b) Defined benefit pension plans Accumulated other comprehensive (loss) income Balance at December 31, 2015 $ (159 ) $ 9 $ 8 $ (89 ) $ (231 ) 2016 net change 262 5 — (1 ) 266 Balance at June 30, 2016 $ 103 $ 14 $ 8 $ (90 ) $ 35 Balance at December 31, 2016 $ (273 ) $ 14 $ 8 $ (90 ) $ (341 ) 2017 net change 96 — 1 (1 ) 96 Balance at June 30, 2017 $ (177 ) $ 14 $ 9 $ (91 ) $ (245 ) (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) income. Three months ended June 30, 2017 ($ in millions) Before tax Tax effect After tax Investment securities Net unrealized gains arising during the period $ 132 $ (37 ) $ 95 Less: Net realized gains reclassified to income from continuing operations 23 (a) (3 ) (b) 20 Net change 109 (34 ) 75 Translation adjustments Net unrealized gains arising during the period 4 (1 ) 3 Net investment hedges (c) Net unrealized losses arising during the period (4 ) 1 (3 ) Cash flow hedges (c) Net unrealized gains arising during the period 1 — 1 Other comprehensive income $ 110 $ (34 ) $ 76 (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 June 30, 2016 ($ in millions) Before tax Tax effect After tax Investment securities Net unrealized gains arising during the period $ 185 $ (25 ) $ 160 Less: Net realized gains reclassified to income from continuing operations 39 (a) 1 (b) 40 Net change 146 (26 ) 120 Translation adjustments Net unrealized losses arising during the period (1 ) — (1 ) Less: Net realized losses reclassified to income from discontinued operations, net of tax (1 ) — (1 ) Net change — — — Other comprehensive income $ 146 $ (26 ) $ 120 (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 . Six months ended June 30, 2017 ($ in millions) Before tax Tax effect After tax Investment securities Net unrealized gains arising during the period $ 183 $ (42 ) $ 141 Less: Net realized gains reclassified to income from continuing operations 50 (a) (5 ) (b) 45 Net change 133 (37 ) 96 Translation adjustments Net unrealized gains arising during the period 6 (2 ) 4 Net investment hedges (c) Net unrealized losses arising during the period (6 ) 2 (4 ) Cash flow hedges (c) Net unrealized gains arising during the period 1 — 1 Defined benefit pension plans Net unrealized losses arising during the period (1 ) — (1 ) Other comprehensive income $ 133 $ (37 ) $ 96 (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 . Six months ended June 30, 2016 ($ in millions) Before Tax Tax Effect After Tax Investment securities Net unrealized gains arising during the period $ 465 $ (129 ) $ 336 Less: Net realized gains reclassified to income from continuing operations 93 (a) (19 ) (b) 74 Net change 372 (110 ) 262 Translation adjustments Net unrealized gains arising during the period 12 (5 ) 7 Less: Net realized losses reclassified to income from discontinued operations, net of tax (1 ) — (1 ) Net change 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 $ 378 $ (112 ) $ 266 (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	6 Months Ended
	Jun. 30, 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 June 30, Six months ended June 30, ( $ in millions, except per share data; shares in thousands ) (a) 2017 2016 2017 2016 Net income from continuing operations $ 254 $ 357 $ 467 $ 604 Preferred stock dividends — (15 ) — (30 ) Net income from continuing operations attributable to common shareholders 254 342 467 574 (Loss) income from discontinued operations, net of tax (2 ) 3 (1 ) 6 Net income attributable to common shareholders $ 252 $ 345 $ 466 $ 580 Basic weighted-average common shares outstanding (b) 457,891 485,370 461,904 484,802 Diluted weighted-average common shares outstanding (b) 458,819 486,074 462,802 485,364 Basic earnings per common share Net income from continuing operations $ 0.55 $ 0.70 $ 1.01 $ 1.18 (Loss) income from discontinued operations, net of tax (0.01 ) 0.01 — 0.01 Net income $ 0.55 $ 0.71 $ 1.01 $ 1.20 Diluted earnings per common share Net income from continuing operations $ 0.55 $ 0.70 $ 1.01 $ 1.18 (Loss) income from discontinued operations, net of tax (0.01 ) 0.01 — 0.01 Net income $ 0.55 $ 0.71 $ 1.01 $ 1.19 (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 and six months ended June 30, 2017 , and 2016 .

Regulatory Capital and Other Re

Regulatory Capital and Other Regulatory Matters	6 Months Ended
	Jun. 30, 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 FRB 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). As a requirement of FRB membership, we held $444 million of FRB stock at June 30, 2017. 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. 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. June 30, 2017 December 31, 2016 Required minimum Well-capitalized minimum ( $ in millions ) Amount Ratio Amount Ratio Capital ratios Common Equity Tier 1 (to risk-weighted assets) Ally Financial Inc. $ 13,066 9.47 % $ 12,978 9.37 % 4.50 % (a) Ally Bank 18,975 17.89 17,888 16.70 4.50 6.50 % Tier 1 (to risk-weighted assets) Ally Financial Inc. $ 15,417 11.18 % $ 15,147 10.93 % 6.00 % 6.00 % Ally Bank 18,975 17.89 17,888 16.70 6.00 8.00 Total (to risk-weighted assets) Ally Financial Inc. $ 17,704 12.83 % $ 17,419 12.57 % 8.00 % 10.00 % Ally Bank 19,651 18.53 18,458 17.24 8.00 10.00 Tier 1 leverage (to adjusted quarterly average assets) (b) Ally Financial Inc. $ 15,417 9.51 % $ 15,147 9.54 % 4.00 % (a) Ally Bank 18,975 15.31 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 June 30, 2017 , Ally and Ally Bank were “well-capitalized” and met all applicable 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 non-objection from the FRB for capital actions which included a quarterly cash dividend of $0.08 per share of our common stock 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 of $0.08 per share 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 through the second quarter of 2017. 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 that program, we repurchased $699 million , or 35,625,615 shares of common stock. At June 30, 2017 , we had 452,291,918 shares of common stock outstanding, representing a decrease of 6.5% compared to 483,753,360 shares of common stock outstanding at June 30, 2016. On April 5, 2017, we submitted our 2017 capital plan and stress test results to the FRB. On June 23, 2017, we publicly disclosed summary results of the stress test under the most severe scenario in accordance with regulatory requirements. On June 28, 2017, we received a non-objection to our capital plan from the FRB, including the proposed capital actions contained in our submission. The capital actions include a 50% increase in the quarterly cash dividend on common stock from $0.08 per share to $0.12 per share, and a 9% increase in our share repurchase program, which has been authorized by the Ally Board of Directors, permitting us to repurchase up to $760 million of our common stock from time to time from the third quarter of 2017 through the second quarter of 2018. On July 18, 2017 , the Ally Board of Directors declared a quarterly cash dividend payment of $0.12 per share on all common stock. Refer to Note 26 for further information regarding this common share dividend. 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. The amount and size of any future dividends and share repurchases will depend upon our results of operations, capital levels, future opportunities, consideration and approval by the Ally Board of Directors, and other considerations. 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. For the 2017 cycle, the FRB's qualitative assessment of Ally's capital plan began in the third quarter of 2017. 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, and modified Ally's reporting requirements to reduce certain reporting burdens related to capital planning and stress testing.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	6 Months Ended
	Jun. 30, 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, and options 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 available-for-sale securities, 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, and options 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. As of June 30, 2017, there were no open hedges related to our held-for-investment retail automotive loan assets. Periodically, we may also execute fair value hedges of U.S. Treasury positions within our available-for-sale investment portfolio. Other derivatives qualifying for hedge accounting consist of pay-fixed swaps designated as cash flow hedges of the expected future cash flows in the form of interest payments on certain variable-rate borrowings. 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. We also enter into interest rate lock commitments and forward-sale commitments that are executed as part of our mortgage business that meet the accounting definition of a derivative. 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. These payments are characterized as collateral for over-the-counter (OTC) derivatives. For exchange-traded derivatives, these payments are recognized as settlements rather than collateral. 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 second quarter of 2017 or 2016. We placed cash collateral totaling $92 million and securities collateral totaling $56 million at June 30, 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 June 30, 2017 , and December 31, 2016 , we placed cash collateral totaling $11 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 $6 million and $10 million at June 30, 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. 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 June 30, 2017 , and December 31, 2016 , we received noncash collateral of $3 million and $6 million , respectively. Included in these amounts is noncash collateral where we have been granted the right to sell or pledge the underlying assets. We have not sold or pledged any of the noncash collateral received under these agreements. Balance Sheet Presentation The following table summarizes the fair value amounts of derivative instruments reported on our Condensed Consolidated Balance Sheet . The fair value amounts are presented on a gross basis, are segregated by derivatives that are designated and qualifying as hedging instruments or those that are not, and are further segregated by type of contract within those two categories. Notional amounts are reference amounts from which contractual obligations are derived and are not recorded on the balance sheet. In our view, derivative notional is not an accurate measure of our derivative exposure when viewed in isolation from other factors, such as market rate fluctuations and counterparty credit risk. June 30, 2017 December 31, 2016 Derivative contracts in a Notional amount Derivative contracts in a Notional amount ($ in millions) receivable position (a) payable position (b) receivable position (a) payable position (b) Derivatives designated as accounting hedges Interest rate contracts Swaps (c) (d) (e) (f) (g) $ — $ — $ 4,225 $ 19 $ 21 $ 4,731 Foreign exchange contracts Forwards — 3 154 1 — 171 Total derivatives designated as accounting hedges — 3 4,379 20 21 4,902 Derivatives not designated as accounting hedges Interest rate contracts Swaps — — 15 — — 137 Futures and forwards — — 103 — — — Written options 1 39 12,449 — 73 14,518 Purchased options 39 — 12,346 73 — 14,517 Total interest rate risk 40 39 24,913 73 73 29,172 Foreign exchange contracts Futures and forwards 1 1 142 1 — 92 Total foreign exchange risk 1 1 142 1 — 92 Equity contracts Written options — — — — 1 — Purchased options — — — 1 — — Total equity risk — — — 1 1 — Total derivatives not designated as accounting hedges 41 40 25,055 75 74 29,264 Total derivatives $ 41 $ 43 $ 29,434 $ 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 $0 million and $7 million at June 30, 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 June 30, 2017 , and December 31, 2016 , respectively. (c) Includes fair value hedges consisting of receive-fixed swaps on fixed-rate unsecured debt obligations with $0 million and $8 million in a receivable position, $0 million and $14 million in a payable position, and a $3.3 billion and $1.7 billion notional amount at June 30, 2017 , and December 31, 2016 , respectively. The hedge notional amount of $3.3 billion at June 30, 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 $240 million notional amount at both June 30, 2017 , and December 31, 2016 . (e) Other fair value hedges include pay-fixed swaps on portfolios of held-for-investment automotive loan assets with $0 million and $10 million in a receivable position, $0 million and $1 million in a payable position, and a $0.0 billion and $2.8 billion notional amount at June 30, 2017 , and December 31, 2016 , respectively. (f) Includes cash flow hedge of pay-fixed swap on variable-rate borrowings of a secured credit facility with $0 million in a receivable and payable position, and $650 million of notional amount at June 30, 2017 . (g) Derivative contracts in a receivable and payable position exclude open trade equity on derivatives cleared through certain clearing counterparties. Any associated collateral exchanged with our central clearing counterparties are treated as settlements of the derivative exposure, rather than collateral. Such payments are recognized as settlements of the derivatives contracts in a receivable and payable position in our Condensed Consolidated Balance Sheet. 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 June 30, Six months ended June 30, ( $ in millions ) 2017 2016 2017 2016 Derivatives qualifying for hedge accounting (Loss) gain recognized in earnings on derivatives Interest rate contracts Interest and fees on finance receivables and loans (a) $ (1 ) $ (6 ) $ 1 $ (34 ) Interest on long-term debt (b) 20 51 24 242 Gain (loss) recognized in earnings on hedged items Interest rate contracts Interest and fees on finance receivables and loans (c) 1 5 (3 ) 33 Interest on long-term debt (d) (20 ) (50 ) (23 ) (246 ) Total derivatives qualifying for hedge accounting — — (1 ) (5 ) Derivatives not designated as accounting hedges (Loss) gain recognized in earnings on derivatives Interest rate contracts Gain on mortgage and automotive loans, net 1 — 1 — Other income, net of losses (1 ) 1 (3 ) 3 Total interest rate contracts — 1 (2 ) 3 Foreign exchange contracts (e) Interest on long-term debt — (1 ) — (2 ) Other income, net of losses (3 ) 1 (4 ) (3 ) Total foreign exchange contracts (3 ) — (4 ) (5 ) Equity contracts Compensation and benefits expense — (1 ) — (2 ) Total equity contracts — (1 ) — (2 ) Loss recognized in earnings on derivatives $ (3 ) $ — $ (7 ) $ (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 $0 million and $5 million for the three months ended June 30, 2017 , and 2016 , respectively, and $1 million and $12 million for the six months ended June 30, 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 $7 million and $11 million for the three months ended June 30, 2017 , and 2016, respectively, and $12 million and $27 million for the six months ended June 30, 2017 , and 2016 , respectively. Amounts also 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 $2 million for the three months ended June 30, 2017 , and 2016, respectively, and $0 million and $3 million for the six months ended June 30, 2017 , and 2016 , respectively. (c) Amounts exclude losses related to amortization of deferred loan basis adjustments on the de-designated hedged item of $6 million and $4 million for the three months ended June 30, 2017 , and 2016 , respectively, and $11 million and $9 million for the six months ended June 30, 2017 , and 2016 , respectively. (d) Amounts exclude gains related to amortization of deferred debt basis adjustments on the de-designated hedged item of $20 million and $21 million for the three months ended June 30, 2017 , and 2016 , respectively, and $40 million and $39 million for the six months ended June 30, 2017 , and 2016 , respectively. Amounts also 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 June 30, 2017 , and 2016 , respectively, and $1 million and $0 million for the six months ended June 30, 2017 , and 2016 , respectively. (e) Amounts exclude gains and losses related to the revaluation of the related foreign-denominated debt or receivable. Losses of $4 million and $1 million were recognized for the three months ended June 30, 2017 , and 2016 , respectively, and gains of $5 million and $3 million were recognized for the six months ended June 30, 2017 , and 2016 , respectively. In connection with derivative instruments used in cash flow and net investment hedge accounting relationships, losses of $4 million and $0 million were recognized in other comprehensive income for the three months ended June 30, 2017 , and 2016 , respectively, and losses of $6 million were recognized in other comprehensive income for both the six months ended June 30, 2017 , and 2016 . 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 $4 million and $0 million for the three months ended June 30, 2017 , and 2016, respectively, and $7 million and $11 million for the six months ended June 30, 2017, and 2016.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	Income Taxes We recognized total income tax expense from continuing operations of $122 million and $235 million for the three months and six months ended June 30, 2017 , respectively, compared to $56 million and $206 million for the same periods in 2016 . The increases in income tax expense for the three months and six months ended June 30, 2017 , compared to the same periods in 2016 , were primarily driven by a non-recurring tax benefit in the second quarter of 2016 due to a U.S. tax reserve release related to a prior-year federal return that reduced our liability for unrecognized tax benefits by $175 million . This benefit was partially offset by the establishment of a valuation allowance on capital loss carryforwards for the three months ended June 30, 2016, and a decrease in pretax earnings. 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	6 Months Ended
	Jun. 30, 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. 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 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 also enter into interest rate lock commitments and forward-sale commitments that are executed as part of our mortgage business. These meet the accounting definition of a derivative and therefore are recorded as derivatives on our Condensed Consolidated Balance Sheet . Because these derivatives are valued using internal pricing models, they are classified as Level 3. 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 June 30, 2017 ($ in millions) Level 1 Level 2 Level 3 Total Assets Investment securities Available-for-sale securities Debt securities U.S. Treasury $ 1,852 $ — $ — $ 1,852 U.S. States and political subdivisions — 782 — 782 Foreign government 7 143 — 150 Agency mortgage-backed residential — 13,676 — 13,676 Mortgage-backed residential — 2,038 — 2,038 Mortgage-backed commercial — 475 — 475 Asset-backed — 1,014 — 1,014 Corporate debt — 1,272 — 1,272 Total debt securities 1,859 19,400 — 21,259 Equity securities (a) 505 — — 505 Total available-for-sale securities 2,364 19,400 — 21,764 Mortgage loans held-for-sale — — 3 3 Interests retained in financial asset sales — — 5 5 Derivative contracts in a receivable position (b) Interest rate — 39 1 40 Foreign currency — 1 — 1 Total derivative contracts in a receivable position — 40 1 41 Total assets $ 2,364 $ 19,440 $ 9 $ 21,813 Liabilities Accrued expenses and other liabilities Derivative contracts in a payable position (b) Interest rate $ — $ (39 ) $ — $ (39 ) Foreign currency — (4 ) — (4 ) Total derivative contracts in a payable position — (43 ) — (43 ) Total liabilities $ — $ (43 ) $ — $ (43 ) (a) Our investment in any one industry did not exceed 18% . (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 gains Fair value at June 30, 2017 Net unrealized gains included in earnings still held at June 30, 2017 ($ in millions) Fair value at April 1, 2017 included in earnings included in OCI Purchases Sales Issuances Settlements Assets Mortgage loans held-for-sale $ 1 $ — $ — $ 20 $ (18 ) $ — $ — $ 3 $ — Other assets Interests retained in financial asset sales 31 1 — — 4 — (31 ) 5 — Derivative assets — 1 — — — — — 1 1 Total assets $ 32 $ 2 $ — $ 20 $ (14 ) $ — $ (31 ) $ 9 $ 1 Level 3 recurring fair value measurements Fair value at April 1, 2016 Net realized/unrealized gains Purchases Sales Issuances Settlements Fair value at June 30, 2016 Net unrealized gains included in earnings still held at June 30, 2016 ($ in millions) included in earnings included in OCI Assets Other assets Interests retained in financial asset sales $ 31 $ 1 (a) $ — $ — $ 2 $ — $ (3 ) $ 31 $ — Total assets $ 31 $ 1 $ — $ — $ 2 $ — $ (3 ) $ 31 $ — (a) Reported as other income, net of losses, in the Condensed Consolidated Statement of Comprehensive Income . Level 3 recurring fair value measurements Net realized/unrealized gains Fair value at June 30, 2017 Net unrealized gains included in earnings still held at June 30, 2017 ($ in millions) Fair value at Jan. 1, 2017 included in earnings included in OCI Purchases Sales Issuances Settlements Assets Mortgage loans held-for-sale $ — $ — $ — $ 23 $ (20 ) $ — $ — $ 3 $ — Other assets Interests retained in financial asset sales 29 1 — — 8 — (33 ) 5 — Derivative assets — 1 — — — — — 1 1 Total assets $ 29 $ 2 $ — $ 23 $ (12 ) $ — $ (33 ) $ 9 $ 1 Level 3 recurring fair value measurements Fair value at Jan. 1, 2016 Net realized/unrealized gains Purchases Sales Issuances Settlements Fair value at June 30, 2016 Net unrealized gains included in earnings still held at June 30, 2016 ($ in millions) included in earnings included in OCI Assets Other assets Interests retained in financial asset sales $ 40 $ 3 (a) $ — $ — $ 6 $ — $ (18 ) $ 31 $ — Total assets $ 40 $ 3 $ — $ — $ 6 $ — $ (18 ) $ 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 fair value measurements Lower-of-cost or fair value or valuation reserve allowance Total gain (loss) included in earnings for the three months ended Total gain (loss) included in earnings for the six months ended June 30, 2017 ($ in millions) Level 1 Level 2 Level 3 Total Assets Loans held-for-sale, net $ — $ — $ 13 $ 13 $ — n/m (a) n/m (a) Commercial finance receivables and loans, net (b) Commercial and industrial Automotive — — 45 45 $ (6 ) n/m (a) n/m (a) Other — — 34 34 (25 ) n/m (a) n/m (a) Total commercial finance receivables and loans, net — — 79 79 (31 ) n/m (a) n/m (a) Other assets Repossessed and foreclosed assets (c) — — 13 13 (1 ) n/m (a) n/m (a) Other — — 4 4 — n/m (a) n/m (a) Total assets $ — $ — $ 109 $ 109 $ (32 ) n/m 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 2017. 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. Nonrecurring fair value measurements Lower-of-cost or fair value or valuation reserve allowance Total gain included in earnings for the three months ended Total gain included in earnings for the six months ended June 30, 2016 ($ in millions) Level 1 Level 2 Level 3 Total Assets Loans held-for-sale, net $ — $ — $ 15 $ 15 $ — n/m (a) n/m (a) Commercial finance receivables and loans, net (b) Commercial and industrial Automotive — — 43 43 (6 ) n/m (a) n/m (a) Other — — 46 46 (18 ) n/m (a) n/m (a) Total commercial finance receivables and loans, net — — 89 89 (24 ) n/m (a) n/m (a) Other assets Repossessed and foreclosed assets (c) — — 10 10 (3 ) n/m (a) n/m (a) Other — — 5 5 — n/m (a) n/m (a) Total assets $ — $ — $ 119 $ 119 $ (27 ) n/m 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 June 30, 2017 , and December 31, 2016 . Estimated fair value ($ in millions) Carrying value Level 1 Level 2 Level 3 Total June 30, 2017 Financial assets Held-to-maturity securities $ 1,189 $ — $ 1,156 $ — $ 1,156 Loans held-for-sale, net 17 — — 17 17 Finance receivables and loans, net 119,303 — — 121,029 121,029 Nonmarketable equity investments (a) 925 — 898 25 923 Financial liabilities Deposit liabilities $ 86,183 $ — $ — $ 84,287 $ 84,287 Short-term borrowings 10,712 — — 10,714 10,714 Long-term debt 49,145 — 32,371 19,163 51,534 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 (a) Excludes investments with a carrying value of $13 million and fair value of $34 million at June 30, 2017, for which fair value is measured at net asset value (or its equivalent) as a practical expedient. 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. For our credit facilities, which are floating rate in nature and where pricing occurs on a more frequent basis, the carrying amount or par value is considered to be a reasonable estimate of fair value. As of June 30, 2017, we began using quoted market prices of similar instruments for certain of our long-term debt associated with asset-backed securitizations for which observable market information exists. As a result, the corresponding financial instruments have been transferred from Level 3 to Level 2 within the fair value hierarchy following the change in valuation technique driven by the availability of an independent pricing service. • 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	6 Months Ended
	Jun. 30, 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 June 30, 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) presented in the Condensed Consolidated Balance Sheet Gross amounts not offset in the Condensed Consolidated Balance Sheet June 30, 2017 ($ in millions) Financial instruments Collateral (a) (b) (c) Net amount Assets Derivative assets in net asset positions $ 39 $ — $ 39 $ — $ — $ 39 Derivative assets in net liability positions 1 — 1 (1 ) — — Derivative assets with no offsetting arrangements 1 — 1 — — 1 Total assets (d) $ 41 $ — $ 41 $ (1 ) $ — $ 40 Liabilities Derivative liabilities in net liability positions $ (43 ) $ — $ (43 ) $ — $ 4 $ (39 ) Derivative liabilities in net asset positions — — — — — — Total derivative liabilities (d) (43 ) — (43 ) — 4 (39 ) Securities sold under agreements to repurchase (e) (1,322 ) — (1,322 ) — 1,322 — Total liabilities $ (1,365 ) $ — $ (1,365 ) $ — $ 1,326 $ (39 ) (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. $3 million of noncash derivative collateral pledged to us was excluded at June 30, 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 $3 million at June 30, 2017 . We have not sold or pledged any of the noncash collateral received under these agreements as of June 30, 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) presented in the Condensed Consolidated Balance Sheet Gross amounts not offset in the Condensed Consolidated Balance Sheet December 31, 2016 ( $ in millions ) Financial instruments Collateral (a) (b) (c) 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	6 Months Ended
	Jun. 30, 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 debt issuances, 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, financial results related to Ally Invest are currently 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 June 30, ($ 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 $ 932 $ 14 $ 32 $ 48 $ 41 $ 1,067 Other revenue 107 245 1 10 25 388 Total net revenue 1,039 259 33 58 66 1,455 Provision for loan losses 266 — 1 6 (4 ) 269 Total noninterest expense 426 280 25 17 62 810 Income (loss) from continuing operations before income tax expense $ 347 $ (21 ) $ 7 $ 35 $ 8 $ 376 Total assets $ 115,447 $ 7,308 $ 8,902 $ 3,552 $ 29,136 $ 164,345 2016 Net financing revenue and other interest income (loss) $ 929 $ 16 $ 26 $ 29 $ (16 ) $ 984 Other revenue 77 259 — 4 34 374 Total net revenue 1,006 275 26 33 18 1,358 Provision for loan losses 170 — — 3 (1 ) 172 Total noninterest expense 410 293 17 16 37 773 Income (loss) from continuing operations before income tax expense $ 426 $ (18 ) $ 9 $ 14 $ (18 ) $ 413 Total assets $ 112,356 $ 7,193 $ 8,014 $ 2,989 $ 27,379 $ 157,931 (a) Net financing revenue and other interest income after the provision for loan losses totaled $798 million and $812 million for the three months ended June 30, 2017 , and 2016 , respectively. Six months ended June 30, ($ 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 $ 1,824 $ 29 $ 66 $ 82 $ 45 $ 2,046 Other revenue 208 509 1 28 38 784 Total net revenue 2,032 538 67 110 83 2,830 Provision for loan losses 534 — 2 12 (8 ) 540 Total noninterest expense 863 519 49 38 119 1,588 Income (loss) from continuing operations before income tax expense $ 635 $ 19 $ 16 $ 60 $ (28 ) $ 702 Total assets $ 115,447 $ 7,308 $ 8,902 $ 3,552 $ 29,136 $ 164,345 2016 Net financing revenue and other interest income (loss) $ 1,825 $ 30 $ 46 $ 57 $ (23 ) $ 1,935 Other revenue 154 513 — 10 73 750 Total net revenue 1,979 543 46 67 50 2,685 Provision for loan losses 379 — 3 9 1 392 Total noninterest expense 837 511 32 33 70 1,483 Income (loss) from continuing operations before income tax expense $ 763 $ 32 $ 11 $ 25 $ (21 ) $ 810 Total assets $ 112,356 $ 7,193 $ 8,014 $ 2,989 $ 27,379 $ 157,931 (a) Net financing revenue and other interest income after the provision for loan losses totaled $1,506 million and $1,543 million for the six months ended June 30, 2017 , and 2016 , respectively.

Parent and Guarantor Condensed

Parent and Guarantor Condensed Consolidating Financial Statements	6 Months Ended
	Jun. 30, 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 June 30, 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 June 30, 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 ) $ — $ 1,482 $ — $ 1,447 Interest and fees on finance receivables and loans — intercompany 3 — 2 (5 ) — Interest and dividends on investment securities and other earning assets — — 146 — 146 Interest on cash and cash equivalents 2 — 5 — 7 Interest-bearing cash — intercompany — — 2 (2 ) — Operating leases 3 — 485 — 488 Total financing (loss) revenue and other interest income (27 ) — 2,122 (7 ) 2,088 Interest expense Interest on deposits 1 — 249 — 250 Interest on short-term borrowings 19 — 14 — 33 Interest on long-term debt 274 — 143 — 417 Interest on intercompany debt 4 — 3 (7 ) — Total interest expense 298 — 409 (7 ) 700 Net depreciation expense on operating lease assets 3 — 318 — 321 Net financing revenue (328 ) — 1,395 — 1,067 Cash dividends from subsidiaries Nonbank subsidiaries 387 — — (387 ) — Other revenue Insurance premiums and service revenue earned — — 227 — 227 Gain on mortgage and automotive loans, net 32 — 4 — 36 Loss on extinguishment of debt — — (1 ) — (1 ) Other gain on investments, net — — 23 — 23 Other income, net of losses 163 — 211 (271 ) 103 Total other revenue 195 — 464 (271 ) 388 Total net revenue 254 — 1,859 (658 ) 1,455 Provision for loan losses 82 — 187 — 269 Noninterest expense Compensation and benefits expense 19 — 246 — 265 Insurance losses and loss adjustment expenses — — 125 — 125 Other operating expenses 213 — 478 (271 ) 420 Total noninterest expense 232 — 849 (271 ) 810 (Loss) income from continuing operations before income tax (benefit) expense and undistributed income (loss) of subsidiaries (60 ) — 823 (387 ) 376 Income tax (benefit) expense from continuing operations (93 ) — 215 — 122 Net income from continuing operations 33 — 608 (387 ) 254 Loss from discontinued operations, net of tax — — (2 ) — (2 ) Undistributed income (loss) of subsidiaries Bank subsidiary 375 375 — (750 ) — Nonbank subsidiaries (156 ) — — 156 — Net income 252 375 606 (981 ) 252 Other comprehensive income, net of tax 76 50 72 (122 ) 76 Comprehensive income $ 328 $ 425 $ 678 $ (1,103 ) $ 328 Three months ended June 30, 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 $ (28 ) $ — $ 1,293 $ — $ 1,265 Interest and fees on finance receivables and loans — intercompany 3 — 2 (5 ) — Interest and dividends on investment securities and other earning assets — — 99 — 99 Interest on cash and cash equivalents 1 — 3 — 4 Interest-bearing cash — intercompany — — 2 (2 ) — Operating leases 5 — 696 — 701 Total financing (loss) revenue and other interest income (19 ) — 2,095 (7 ) 2,069 Interest expense Interest on deposits 2 — 201 — 203 Interest on short-term borrowings 10 — 2 — 12 Interest on long-term debt 290 — 146 — 436 Interest on intercompany debt 4 — 3 (7 ) — Total interest expense 306 — 352 (7 ) 651 Net depreciation expense on operating lease assets 3 — 431 — 434 Net financing revenue (328 ) — 1,312 — 984 Cash dividends from subsidiaries Nonbank subsidiaries 148 — — (148 ) — Other revenue Insurance premiums and service revenue earned — — 236 — 236 (Loss) gain on mortgage and automotive loans, net (2 ) — 5 — 3 Other gain on investments, net — — 39 — 39 Other income, net of losses 317 — 214 (435 ) 96 Total other revenue 315 — 494 (435 ) 374 Total net revenue 135 — 1,806 (583 ) 1,358 Provision for loan losses 88 — 84 — 172 Noninterest expense Compensation and benefits expense 139 — 103 — 242 Insurance losses and loss adjustment expenses — — 145 — 145 Other operating expenses 317 — 502 (433 ) 386 Total noninterest expense 456 — 750 (433 ) 773 (Loss) income from continuing operations before income tax (benefit) expense and undistributed income (loss) of subsidiaries (409 ) — 972 (150 ) 413 Income tax (benefit) expense from continuing operations (65 ) (82 ) 203 — 56 Net (loss) income from continuing operations (344 ) 82 769 (150 ) 357 Income from discontinued operations, net of tax 3 — — — 3 Undistributed income (loss) of subsidiaries Bank subsidiary 336 336 — (672 ) — Nonbank subsidiaries 365 (2 ) — (363 ) — Net income 360 416 769 (1,185 ) 360 Other comprehensive income, net of tax 120 62 91 (153 ) 120 Comprehensive income $ 480 $ 478 $ 860 $ (1,338 ) $ 480 Six months ended June 30, 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 $ (70 ) $ — $ 2,885 $ — $ 2,815 Interest and fees on finance receivables and loans — intercompany 7 — 4 (11 ) — Interest and dividends on investment securities and other earning assets — — 281 (1 ) 280 Interest on cash and cash equivalents 4 — 8 — 12 Interest-bearing cash — intercompany — — 3 (3 ) — Operating leases 6 — 1,025 — 1,031 Total financing (loss) revenue and other interest income (53 ) — 4,206 (15 ) 4,138 Interest expense Interest on deposits 2 — 479 — 481 Interest on short-term borrowings 36 — 24 — 60 Interest on long-term debt 556 — 285 — 841 Interest on intercompany debt 8 — 7 (15 ) — Total interest expense 602 — 795 (15 ) 1,382 Net depreciation expense on operating lease assets 5 — 705 — 710 Net financing revenue (660 ) — 2,706 — 2,046 Cash dividends from subsidiaries Nonbank subsidiaries 427 — — (427 ) — Other revenue Insurance premiums and service revenue earned — — 468 — 468 Gain on mortgage and automotive loans, net 30 — 20 — 50 Loss on extinguishment of debt — — (2 ) — (2 ) Other gain on investments, net — — 50 — 50 Other income, net of losses 431 — 435 (648 ) 218 Total other revenue 461 — 971 (648 ) 784 Total net revenue 228 — 3,677 (1,075 ) 2,830 Provision for loan losses 189 — 351 — 540 Noninterest expense Compensation and benefits expense 140 — 410 — 550 Insurance losses and loss adjustment expenses — — 213 — 213 Other operating expenses 501 — 972 (648 ) 825 Total noninterest expense 641 — 1,595 (648 ) 1,588 (Loss) income from continuing operations before income tax (benefit) expense and undistributed income of subsidiaries (602 ) — 1,731 (427 ) 702 Income tax (benefit) expense from continuing operations (227 ) — 462 — 235 Net (loss) income from continuing operations (375 ) — 1,269 (427 ) 467 Income (loss) from discontinued operations, net of tax 2 — (3 ) — (1 ) Undistributed income of subsidiaries Bank subsidiary 764 764 — (1,528 ) — Nonbank subsidiaries 75 — — (75 ) — Net income 466 764 1,266 (2,030 ) 466 Other comprehensive income, net of tax 96 55 91 (146 ) 96 Comprehensive income $ 562 $ 819 $ 1,357 $ (2,176 ) $ 562 Six months ended June 30, 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 $ (66 ) $ — $ 2,566 $ — $ 2,500 Interest and fees on finance receivables and loans — intercompany 6 — 4 (10 ) — Interest and dividends on investment securities and other earning assets — — 201 — 201 Interest on cash and cash equivalents 2 — 5 — 7 Interest-bearing cash — intercompany — — 5 (5 ) — Operating leases 10 — 1,460 — 1,470 Total financing (loss) revenue and other interest income (48 ) — 4,241 (15 ) 4,178 Interest expense Interest on deposits 4 — 392 — 396 Interest on short-term borrowings 20 — 5 — 25 Interest on long-term debt 578 — 300 — 878 Interest on intercompany debt 9 — 6 (15 ) — Total interest expense 611 — 703 (15 ) 1,299 Net depreciation expense on operating lease assets 7 — 937 — 944 Net financing revenue (666 ) — 2,601 — 1,935 Cash dividends from subsidiaries Nonbank subsidiaries 629 — — (629 ) — Other revenue Insurance premiums and service revenue earned — — 466 — 466 (Loss) gain on mortgage and automotive loans, net (5 ) — 9 — 4 Loss on extinguishment of debt (2 ) — (2 ) — (4 ) Other gain on investments, net — — 93 — 93 Other income, net of losses 690 — 430 (929 ) 191 Total other revenue 683 — 996 (929 ) 750 Total net revenue 646 — 3,597 (1,558 ) 2,685 Provision for loan losses 148 — 244 — 392 Noninterest expense Compensation and benefits expense 286 — 208 — 494 Insurance losses and loss adjustment expenses — — 218 — 218 Other operating expenses 656 — 1,044 (929 ) 771 Total noninterest expense 942 — 1,470 (929 ) 1,483 (Loss) income from continuing operations before income tax (benefit) expense and undistributed income (loss) of subsidiaries (444 ) — 1,883 (629 ) 810 Income tax (benefit) expense from continuing operations (108 ) (82 ) 396 — 206 Net (loss) income from continuing operations (336 ) 82 1,487 (629 ) 604 Income (loss) from discontinued operations, net of tax 9 — (3 ) — 6 Undistributed income (loss) of subsidiaries Bank subsidiary 607 607 — (1,214 ) — Nonbank subsidiaries 330 (2 ) — (328 ) — Net income 610 687 1,484 (2,171 ) 610 Other comprehensive income, net of tax 266 145 243 (388 ) 266 Comprehensive income $ 876 $ 832 $ 1,727 $ (2,559 ) $ 876 Condensed Consolidating Balance Sheet June 30, 2017 ($ in millions) Parent (a) Guarantors Nonguarantors (a) Consolidating adjustments Ally consolidated Assets Cash and cash equivalents Noninterest-bearing $ 591 $ — $ 923 $ — $ 1,514 Interest-bearing 850 — 2,013 — 2,863 Interest-bearing — intercompany — — 557 (557 ) — Total cash and cash equivalents 1,441 — 3,493 (557 ) 4,377 Available-for-sale securities 6 — 21,764 (6 ) 21,764 Held-to-maturity securities — — 1,284 (95 ) 1,189 Loans held-for-sale, net — — 17 — 17 Finance receivables and loans, net Finance receivables and loans, net 5,733 — 114,795 — 120,528 Intercompany loans to Bank subsidiary 250 — — (250 ) — Nonbank subsidiaries 833 — 380 (1,213 ) — Allowance for loan losses (144 ) — (1,081 ) — (1,225 ) Total finance receivables and loans, net 6,672 — 114,094 (1,463 ) 119,303 Investment in operating leases, net 29 — 9,688 — 9,717 Intercompany receivables from Bank subsidiary 85 — — (85 ) — Nonbank subsidiaries 50 — 145 (195 ) — Investment in subsidiaries Bank subsidiary 18,869 18,869 — (37,738 ) — Nonbank subsidiaries 10,023 — — (10,023 ) — Premiums receivable and other insurance assets — — 2,055 (30 ) 2,025 Other assets 3,482 — 4,684 (2,213 ) 5,953 Total assets $ 40,657 $ 18,869 $ 157,224 $ (52,405 ) $ 164,345 Liabilities Deposit liabilities Noninterest-bearing $ — $ — $ 107 $ — $ 107 Interest-bearing 45 — 86,031 — 86,076 Total deposit liabilities 45 — 86,138 — 86,183 Short-term borrowings 4,706 — 6,006 — 10,712 Long-term debt 20,755 — 28,390 — 49,145 Intercompany debt to Bank subsidiary 95 — — (95 ) — Nonbank subsidiaries 937 — 1,089 (2,026 ) — Intercompany payables to Bank subsidiary 1 — — (1 ) — Nonbank subsidiaries 199 — 110 (309 ) — Interest payable 192 — 207 — 399 Unearned insurance premiums and service revenue — — 2,541 — 2,541 Accrued expenses and other liabilities 254 — 3,852 (2,214 ) 1,892 Total liabilities 27,184 — 128,333 (4,645 ) 150,872 Total equity 13,473 18,869 28,891 (47,760 ) 13,473 Total liabilities and equity $ 40,657 $ 18,869 $ 157,224 $ (52,405 ) $ 164,345 (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 Six months ended June 30, 2017 ($ in millions) Parent Guarantors Nonguarantors Consolidating adjustments Ally consolidated Operating activities Net cash provided by operating activities $ 561 $ — $ 1,856 $ (347 ) $ 2,070 Investing activities Purchases of available-for-sale securities — — (5,853 ) — (5,853 ) Proceeds from sales of available-for-sale securities — — 2,162 — 2,162 Proceeds from maturities and repayments of available-for-sale securities — — 1,230 — 1,230 Purchases of held-to-maturity securities — — (313 ) — (313 ) Proceeds from maturities and repayments of held-to-maturity securities — — 17 — 17 Net change in investment securities — intercompany 1 — 269 (270 ) — Purchases of finance receivables and loans held-for-investment (35 ) — (1,782 ) — (1,817 ) Proceeds from sales of finance receivables and loans originated as held-for-investment 67 — 1,213 — 1,280 Originations and repayments of finance receivables and loans held-for-investment and other, net 1,044 — (676 ) (1,956 ) (1,588 ) Net change in loans — intercompany 1,864 — 246 (2,110 ) — Purchases of operating lease assets — — (1,965 ) — (1,965 ) Disposals of operating lease assets 4 — 3,039 — 3,043 Capital contributions to subsidiaries (824 ) — — 824 — Returns of contributed capital 838 — — (838 ) — Net change in restricted cash (45 ) — 524 (5 ) 474 Net change in nonmarketable equity investments — — 107 — 107 Other, net (26 ) — 24 (91 ) (93 ) Net cash provided by (used in) investing activities 2,888 — (1,758 ) (4,446 ) (3,316 ) Financing activities Net change in short-term borrowings — third party 1,083 — (3,045 ) — (1,962 ) Net (decrease) increase in deposits (123 ) — 7,256 — 7,133 Proceeds from issuance of long-term debt — third party 353 — 7,016 1,961 9,330 Repayments of long-term debt — third party (3,323 ) — (11,043 ) — (14,366 ) Net change in debt — intercompany (370 ) — (1,864 ) 2,234 — Repurchase of common stock (373 ) — — — (373 ) Dividends paid — third party (75 ) — — — (75 ) Dividends paid and returns of contributed capital — intercompany — — (1,266 ) 1,266 — Capital contributions from parent — — 824 (824 ) — Net cash used in financing activities (2,828 ) — (2,122 ) 4,637 (313 ) Effect of exchange-rate changes on cash and cash equivalents — — 2 — 2 Net increase (decrease) in cash and cash equivalents 621 — (2,022 ) (156 ) (1,557 ) Cash and cash equivalents at beginning of year 820 — 5,515 (401 ) 5,934 Cash and cash equivalents at June 30, $ 1,441 $ — $ 3,493 $ (557 ) $ 4,377 Six months ended June 30, 2016 ($ in millions) Parent Guarantors Nonguarantors Consolidating adjustments Ally consolidated Operating activities Net cash provided by operating activities $ 146 $ — $ 2,919 $ (629 ) $ 2,436 Investing activities Purchases of available-for-sale securities — — (8,657 ) — (8,657 ) Proceeds from sales of available-for-sale securities — — 6,584 — 6,584 Proceeds from maturities and repayments of available-for-sale securities — — 1,536 — 1,536 Purchases of held-to-maturity securities — — (571 ) — (571 ) Purchases of finance receivables and loans held-for-investment — — (2,442 ) — (2,442 ) Proceeds from sales of finance receivables and loans originated as held-for-investment — — 4,156 — 4,156 Originations and repayments of finance receivables and loans held-for-investment and other (834 ) — (2,377 ) — (3,211 ) Net change in loans — intercompany 61 — (2 ) (59 ) — Purchases of operating lease assets — — (1,472 ) — (1,472 ) Disposals of operating lease assets 9 — 3,038 — 3,047 Acquisitions of subsidiaries, net of cash acquired (288 ) — — — (288 ) Capital contributions to subsidiaries (988 ) — — 988 — Returns of contributed capital 1,971 8 — (1,979 ) — Net change in restricted cash 1 — 481 — 482 Net change in nonmarketable equity investments — — (354 ) — (354 ) Other, net (82 ) — 13 — (69 ) Net cash (used in) provided by investing activities (150 ) 8 (67 ) (1,050 ) (1,259 ) Financing activities Net change in short-term borrowings — third party 123 — (2,235 ) — (2,112 ) Net (decrease) increase in deposits (29 ) — 6,337 — 6,308 Proceeds from issuance of long-term debt — third party 1,115 — 7,905 — 9,020 Repayments of long-term debt — third party (596 ) — (13,709 ) — (14,305 ) Net change in debt — intercompany (8 ) — (62 ) 70 — Redemption of preferred stock (696 ) — — — (696 ) Repurchase of common stock (14 ) — — — (14 ) Dividends paid — third party (30 ) — — — (30 ) Dividends paid and returns of contributed capital — intercompany — (8 ) (2,600 ) 2,608 — Capital contributions from parent — — 988 (988 ) — Net cash used in financing activities (135 ) (8 ) (3,376 ) 1,690 (1,829 ) Effect of exchange-rate changes on cash and cash equivalents — — 3 — 3 Net decrease in cash and cash equivalents (139 ) — (521 ) 11 (649 ) Cash and cash equivalents at beginning of year 1,635 — 5,595 (850 ) 6,380 Cash and cash equivalents at June 30, $ 1,496 $ — $ 5,074 $ (839 ) $ 5,731

Contingencies and Other Risks

Contingencies and Other Risks	6 Months Ended
	Jun. 30, 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 (Case No. 16-013616-CZ). This matter was removed to the U.S. District Court for the Eastern District of Michigan on November 18, 2016. 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 (Case No. 2017-156719-CB). This matter was removed to the U.S. District Court for the Eastern District of Michigan on January 30, 2017. 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 (Case No. 17-003811-CZ). This matter was removed to the U.S. District Court for the Eastern District of Michigan on March 15, 2017. 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. All three matters were remanded from the U.S. District Court for the Eastern District of Michigan to the state circuit courts on May 26, 2017. The parties have agreed to take steps to consolidate the three matters in Wayne County Circuit Court. 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 required 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 was required to meet certain stipulations under the Consent Orders, including a requirement to make monetary payments when ongoing remediation targets were not attained. The Consent Orders terminated by their terms on July 27, 2017. Since 2013, Ally recognized expenses of approximately $240 million for judgments, fines, and monetary remuneration payments to customers related to the Consent Orders. During the term of the Consent Orders, the CFPB and the DOJ were precluded 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 in the future, 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	6 Months Ended
	Jun. 30, 2017
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events Declaration of Quarterly Dividend Payment On July 18, 2017 , the Ally Board of Directors declared a quarterly cash dividend payment of $0.12 per share on all common stock. The dividend is payable on August 15, 2017 , to shareholders of record at the close of business on August 1, 2017.

Description of Business, Basi33

Description of Business, Basis of Presentation, and Changes in Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 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 VIE. 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 . This note was updated to address the Dodd-Frank Act risk retention rules and differs from our description in Note 1 to the Consolidated Financial Statements in our 2016 Annual Report on Form 10-K. 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 changed several aspects of share-based payment accounting. The amendments allowed 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 modified 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 required that all excess tax benefits and tax deficiencies related to share-based payment awards 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 addressed 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 six months ended June 30, 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 core 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 retrospective 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, revenue on certain noninsurance contracts, brokering commissions through our insurance operations, sales of other real estate owned, sales of repossessed and off-lease vehicles, remarketing fee income through SmartAuction, and fee income generated through Ally Invest. 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 and expense upon the origination of the contract and the immediate recognition of certain expenses upon the origination of the contract that are currently deferred. Our assessment is not final; however, we do not expect the impact of the new guidance to these specific contracts to be material to the financial statements. We currently plan to adopt this guidance as of January 1, 2018, and expect to use 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. We currently plan to adopt these amendments on January 1, 2018, and expect 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 operating leases and sales type and direct financing leases (sales type and direct financing leases were both 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. We currently plan to adopt these amendments on January 1, 2019, and expect 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. We are in the process of designing and building the models and procedures that will be used to calculate the credit loss reserves in accordance with these amendments. We currently plan to adopt these amendments on January 1, 2020, and expect 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. The amendments will not impact financial results, but will result in a change in the presentation of restricted cash and restricted cash equivalents within the statement of cash flows. We currently plan to adopt these amendments on January 1, 2018, and expect to use the retrospective approach as required. 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. We currently plan to adopt these amendments on January 1, 2019, and expect to use the modified retrospective approach as required.

Discontinued Operations Discont

Discontinued Operations Discontinued Operations (Policies)	6 Months Ended
	Jun. 30, 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)	6 Months Ended
	Jun. 30, 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 $2 million and $5 million of amortization on these intangible assets during the three months and six months ended June 30, 2017 , respectively. (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)	6 Months Ended
	Jun. 30, 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 June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Pretax (loss) income $ (2 ) $ (2 ) $ (1 ) $ 2 Tax benefit — (5 ) — (4 )

Other Income, Net of Losses (Ta

Other Income, Net of Losses (Tables)	6 Months Ended
	Jun. 30, 2017
Other Nonoperating Income (Expense) [Abstract]
Schedule of Other Nonoperating Income, by Component [Table Text Block]	Three months ended June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Remarketing fees $ 27 $ 25 $ 56 $ 53 Late charges and other administrative fees 25 22 52 47 Servicing fees 14 18 30 31 Income from equity-method investments 5 5 5 11 Other, net 32 26 75 49 Total other income, net of losses $ 103 $ 96 $ 218 $ 191

Reserves for Insurance Losses38

Reserves for Insurance Losses and Loss Adjustment Expenses Reserves for Insurance Losses and Loss Adjustment Expenses (Tables)	6 Months Ended
	Jun. 30, 2017
Reserves for Insurance Losses and Loss 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 211 221 Prior years (a) 2 (3 ) Total net insurance losses and loss adjustment expenses incurred 213 218 Net insurance losses and loss adjustment expenses paid or payable related to: Current year (183 ) (184 ) Prior years (27 ) (25 ) Total net insurance losses and loss adjustment expenses paid or payable (210 ) (209 ) Net reserves for insurance losses and loss adjustment expenses at June 30, 44 58 Plus: Reinsurance recoverable 135 106 Total gross reserves for insurance losses and loss adjustment expenses at June 30, $ 179 $ 164 (a) There have been no material adverse changes to the reserve for prior years.

Other Operating Expenses (Table

Other Operating Expenses (Tables)	6 Months Ended
	Jun. 30, 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 June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Insurance commissions $ 104 $ 97 $ 203 $ 191 Technology and communications 71 67 140 133 Lease and loan administration 39 34 75 66 Advertising and marketing 33 21 63 48 Regulatory and licensing fees 28 21 55 42 Vehicle remarketing and repossession 25 22 53 46 Professional services 27 26 53 50 Premises and equipment depreciation 23 21 45 42 Occupancy 11 12 23 25 Non-income taxes 8 8 16 17 Other 51 57 99 111 Total other operating expenses $ 420 $ 386 $ 825 $ 771

Investment Securities (Tables)

Investment Securities (Tables)	6 Months Ended
	Jun. 30, 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. June 30, 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 $ 1,891 $ — $ (39 ) $ 1,852 $ 1,680 $ — $ (60 ) $ 1,620 U.S. States and political subdivisions 780 13 (11 ) 782 794 7 (19 ) 782 Foreign government 148 2 — 150 157 5 — 162 Agency mortgage-backed residential 13,809 39 (172 ) 13,676 10,473 29 (212 ) 10,290 Mortgage-backed residential 2,063 11 (36 ) 2,038 2,162 5 (70 ) 2,097 Mortgage-backed commercial 474 2 (1 ) 475 537 2 (2 ) 537 Asset-backed 1,010 6 (2 ) 1,014 1,396 6 (2 ) 1,400 Corporate debt 1,273 8 (9 ) 1,272 1,452 7 (16 ) 1,443 Total debt securities (a) (b) 21,448 81 (270 ) 21,259 18,651 61 (381 ) 18,331 Equity securities 549 9 (53 ) 505 642 7 (54 ) 595 Total available-for-sale securities $ 21,997 $ 90 $ (323 ) $ 21,764 $ 19,293 $ 68 $ (435 ) $ 18,926 Held-to-maturity securities Debt securities Agency mortgage-backed residential (c) $ 1,143 $ 2 $ (35 ) $ 1,110 $ 839 $ — $ (50 ) $ 789 Asset-backed retained notes 46 — — 46 — — — — Total held-to-maturity securities $ 1,189 $ 2 $ (35 ) $ 1,156 $ 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 June 30, 2017 , and December 31, 2016 , respectively. (b) Investment securities with a fair value of $3,316 million and $4,881 million at June 30, 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 $1,420 million and $737 million of the underlying investment securities at June 30, 2017 , and December 31, 2016 , respectively. (c) Agency mortgage-backed residential debt securities are held for liquidity purposes. Securities with a fair value of $0 million and $87 million at June 30, 2017 , and December 31, 2016 , respectively, were pledged to secure advances from the FHLB.
Investments Classified by Contractual Maturity Date [Table Text Block]	The maturity distribution of investment securities outstanding is summarized in the following tables. Call or prepayment options may cause actual maturities to differ from contractual maturities. Total Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years ($ in millions) Amount Yield Amount Yield Amount Yield Amount Yield Amount Yield June 30, 2017 Fair value of available-for-sale debt securities (a) U.S. Treasury $ 1,852 1.7 % $ — — % $ 21 1.7 % $ 1,831 1.7 % $ — — % U.S. States and political subdivisions 782 3.1 38 2.5 45 2.4 165 2.8 534 3.3 Foreign government 150 2.5 — — 68 2.6 82 2.4 — — Agency mortgage-backed residential 13,676 3.0 — — — — 3 2.9 13,673 3.0 Mortgage-backed residential 2,038 2.9 — — — — — — 2,038 2.9 Mortgage-backed commercial 475 3.1 — — — — 3 2.9 472 3.1 Asset-backed 1,014 2.9 — — 801 3.0 57 2.9 156 2.7 Corporate debt 1,272 2.9 125 2.3 617 2.6 496 3.2 34 5.2 Total available-for-sale debt securities $ 21,259 2.9 $ 163 2.3 $ 1,552 2.8 $ 2,637 2.1 $ 16,907 3.0 Amortized cost of available-for-sale debt securities $ 21,448 $ 163 $ 1,545 $ 2,675 $ 17,065 Amortized cost of held-to-maturity securities Agency mortgage-backed residential $ 1,143 3.0 % $ — — % $ — — % $ — — % $ 1,143 3.0 % Asset-backed retained notes 46 1.6 4 0.8 41 1.6 1 3.0 — — Total held-to-maturity securities $ 1,189 2.9 $ 4 0.8 $ 41 1.6 $ 1 3.0 $ 1,143 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 (b) $ 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 June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Taxable interest $ 130 $ 89 $ 249 $ 183 Taxable dividends 3 5 5 9 Interest and dividends exempt from U.S. federal income tax 6 5 11 9 Interest and dividends on investment securities $ 139 $ 99 $ 265 $ 201
Schedule of Realized Gain (Loss) [Table Text Block]	The following table presents gross gains and losses realized upon the sales of available-for-sale securities. There were no other-than-temporary impairments upon the sales of available-for-sale securities for either period. Three months ended June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Gross realized gains $ 24 $ 40 $ 51 $ 94 Gross realized losses (a) (1 ) (1 ) (1 ) (1 ) Other gain on investments, net $ 23 $ 39 $ 50 $ 93 (a) Certain available-for-sale securities were sold at a loss in 2017 and 2016 as a result of market conditions within these respective periods (e.g., a downgrade in the rating of a debt security). Any such sales were made in accordance with our risk management policies and practices.
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 June 30, 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 June 30, 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 June 30, 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. June 30, 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 $ 1,829 $ (39 ) $ — $ — $ 1,612 $ (60 ) $ — $ — U.S. States and political subdivisions 401 (10 ) 15 (1 ) 524 (19 ) — — Foreign government 26 — — — 38 — — — Agency mortgage-backed residential 9,293 (162 ) 448 (10 ) 8,052 (196 ) 587 (16 ) Mortgage-backed residential 410 (6 ) 763 (30 ) 813 (17 ) 860 (53 ) Mortgage-backed commercial 102 (1 ) 49 — 47 (1 ) 149 (1 ) Asset-backed 293 (1 ) 107 (1 ) 375 (2 ) 127 — Corporate debt 495 (7 ) 36 (2 ) 744 (14 ) 46 (2 ) Total temporarily impaired debt securities 12,849 (226 ) 1,418 (44 ) 12,205 (309 ) 1,769 (72 ) Temporarily impaired equity securities 140 (9 ) 124 (44 ) 151 (8 ) 269 (46 ) Total temporarily impaired available-for-sale securities $ 12,989 $ (235 ) $ 1,542 $ (88 ) $ 12,356 $ (317 ) $ 2,038 $ (118 )

Finance Receivables and Loans41

Finance Receivables and Loans, Net (Tables)	6 Months Ended
	Jun. 30, 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) June 30, 2017 December 31, 2016 Consumer automotive (a) $ 66,774 $ 65,793 Consumer mortgage Mortgage Finance (b) 8,866 8,294 Mortgage — Legacy (c) 2,428 2,756 Total consumer mortgage 11,294 11,050 Total consumer 78,068 76,843 Commercial Commercial and industrial Automotive 34,782 35,041 Other 3,620 3,248 Commercial real estate — Automotive 4,058 3,812 Total commercial 42,460 42,101 Total finance receivables and loans (d) $ 120,528 $ 118,944 (a) Includes $28 million and $43 million of fair value adjustment for loans in hedge accounting relationships at June 30, 2017 , and December 31, 2016 , respectively. Refer to Note 19 for additional information. (b) Includes loans originated as interest-only mortgage loans of $24 million and $30 million at June 30, 2017 , and December 31, 2016 , respectively, 3% of which are expected to start principal amortization in 2017 , none in 2018 , 34% in 2019 , 43% in 2020 , and none thereafter. (c) Includes loans originated as interest-only mortgage loans of $587 million and $714 million at June 30, 2017 , and December 31, 2016 , respectively, 7% 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 $439 million and $359 million at June 30, 2017 , and December 31, 2016 , respectively, for unearned income, unamortized premiums and discounts, and deferred fees and costs.
Allowance for Credit Losses on Financing Receivables [Table Text Block]	The following tables present an analysis of the activity in the allowance for loan losses on finance receivables and loans. Three months ended June 30, 2017 ($ in millions) Consumer automotive Consumer mortgage Commercial Total Allowance at April 1, 2017 $ 941 $ 86 $ 128 $ 1,155 Charge-offs (a) (290 ) (6 ) — (296 ) Recoveries 91 6 — 97 Net charge-offs (199 ) — — (199 ) Provision for loan losses 260 (3 ) 12 269 Allowance at June 30, 2017 $ 1,002 $ 83 $ 140 $ 1,225 (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. Three months ended June 30, 2016 ($ in millions) Consumer automotive Consumer mortgage Commercial Total Allowance at April 1, 2016 $ 850 $ 115 $ 112 $ 1,077 Charge-offs (a) (227 ) (9 ) (1 ) (237 ) Recoveries 79 5 1 85 Net charge-offs (148 ) (4 ) — (152 ) Provision for loan losses 168 (2 ) 6 172 Other (b) (8 ) — — (8 ) Allowance at June 30, 2016 $ 862 $ 109 $ 118 $ 1,089 (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. Six months ended June 30, 2017 ($ in millions) Consumer automotive Consumer mortgage Commercial Total Allowance at January 1, 2017 $ 932 $ 91 $ 121 $ 1,144 Charge-offs (a) (631 ) (15 ) — (646 ) Recoveries 181 13 — 194 Net charge-offs (450 ) (2 ) — (452 ) Provision for loan losses 527 (6 ) 19 540 Other (b) (7 ) — — (7 ) Allowance at June 30, 2017 $ 1,002 $ 83 $ 140 $ 1,225 Allowance for loan losses at June 30, 2017 Individually evaluated for impairment $ 34 $ 31 $ 32 $ 97 Collectively evaluated for impairment 968 52 108 1,128 Finance receivables and loans at gross carrying value Ending balance $ 66,774 $ 11,294 $ 42,460 $ 120,528 Individually evaluated for impairment 380 242 151 773 Collectively evaluated for impairment 66,394 11,052 42,309 119,755 (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. Six months ended June 30, 2016 ($ in millions) Consumer automotive Consumer mortgage Commercial Total Allowance at January 1, 2016 $ 834 $ 114 $ 106 $ 1,054 Charge-offs (a) (480 ) (19 ) (1 ) (500 ) Recoveries 159 9 1 169 Net charge-offs (321 ) (10 ) — (331 ) Provision for loan losses 375 5 12 392 Other (b) (26 ) — — (26 ) Allowance at June 30, 2016 $ 862 $ 109 $ 118 $ 1,089 Allowance for loan losses at June 30, 2016 Individually evaluated for impairment $ 26 $ 37 $ 23 $ 86 Collectively evaluated for impairment 836 72 95 1,003 Finance receivables and loans at gross carrying value Ending balance $ 63,281 $ 11,084 $ 38,288 $ 112,653 Individually evaluated for impairment 348 254 122 724 Collectively evaluated for impairment 62,933 10,830 38,166 111,929 (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 June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Consumer automotive $ 85 $ 1,560 $ 1,298 $ 4,159 Consumer mortgage 3 4 6 6 Commercial — 28 — 28 Total sales and transfers $ 88 $ 1,592 $ 1,304 $ 4,193
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 June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Consumer automotive $ 611 $ — $ 679 $ — Consumer mortgage 809 1,018 1,136 2,388 Total purchases of finance receivables and loans $ 1,420 $ 1,018 $ 1,815 $ 2,388
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 June 30, 2017 Consumer automotive $ 1,569 $ 350 $ 236 $ 2,155 $ 64,619 $ 66,774 Consumer mortgage Mortgage Finance 32 3 6 41 8,825 8,866 Mortgage — Legacy 34 18 55 107 2,321 2,428 Total consumer mortgage 66 21 61 148 11,146 11,294 Total consumer 1,635 371 297 2,303 75,765 78,068 Commercial Commercial and industrial Automotive 18 — 8 26 34,756 34,782 Other — — — — 3,620 3,620 Commercial real estate — Automotive — — — — 4,058 4,058 Total commercial 18 — 8 26 42,434 42,460 Total consumer and commercial $ 1,653 $ 371 $ 305 $ 2,329 $ 118,199 $ 120,528 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) June 30, 2017 December 31, 2016 Consumer automotive $ 540 $ 598 Consumer mortgage Mortgage Finance 9 10 Mortgage — Legacy 83 89 Total consumer mortgage 92 99 Total consumer 632 697 Commercial Commercial and industrial Automotive 75 33 Other 69 84 Commercial real estate — Automotive 7 5 Total commercial 151 122 Total consumer and commercial finance receivables and loans $ 783 $ 819
Financing Receivable Credit Quality Indicators [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. June 30, 2017 December 31, 2016 ($ in millions) Performing Nonperforming Total Performing Nonperforming Total Consumer automotive $ 66,234 $ 540 $ 66,774 $ 65,195 $ 598 $ 65,793 Consumer mortgage Mortgage Finance 8,857 9 8,866 8,284 10 8,294 Mortgage — Legacy 2,345 83 2,428 2,667 89 2,756 Total consumer mortgage 11,202 92 11,294 10,951 99 11,050 Total consumer $ 77,436 $ 632 $ 78,068 $ 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. June 30, 2017 December 31, 2016 ($ in millions) Pass Criticized (a) Total Pass Criticized (a) Total Commercial and industrial Automotive $ 32,851 $ 1,931 $ 34,782 $ 33,160 $ 1,881 $ 35,041 Other 2,859 761 3,620 2,597 651 3,248 Commercial real estate — Automotive 3,906 152 4,058 3,653 159 3,812 Total commercial $ 39,616 $ 2,844 $ 42,460 $ 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 June 30, 2017 Consumer automotive $ 396 $ 380 $ 102 $ 278 $ 34 Consumer mortgage Mortgage Finance 8 8 4 4 — Mortgage — Legacy 238 234 55 179 31 Total consumer mortgage 246 242 59 183 31 Total consumer 642 622 161 461 65 Commercial Commercial and industrial Automotive 75 75 27 48 5 Other 78 69 10 59 26 Commercial real estate — Automotive 7 7 3 4 1 Total commercial 160 151 40 111 32 Total consumer and commercial finance receivables and loans $ 802 $ 773 $ 201 $ 572 $ 97 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 tables present average balance and interest income for our impaired finance receivables and loans. 2017 2016 Three months ended June 30, ($ in millions) Average balance Interest income Average balance Interest income Consumer automotive $ 391 $ 5 $ 341 $ 4 Consumer mortgage Mortgage Finance 8 — 8 — Mortgage — Legacy 238 3 251 3 Total consumer mortgage 246 3 259 3 Total consumer 637 8 600 7 Commercial Commercial and industrial Automotive 54 1 35 — Other 73 8 65 — Commercial real estate — Automotive 6 — 6 — Total commercial 133 9 106 — Total consumer and commercial finance receivables and loans $ 770 $ 17 $ 706 $ 7 2017 2016 Six months ended June 30, ($ in millions) Average balance Interest income Average balance Interest income Consumer automotive $ 381 $ 10 $ 335 $ 8 Consumer mortgage Mortgage Finance 8 — 8 — Mortgage — Legacy 239 5 253 5 Total consumer mortgage 247 5 261 5 Total consumer 628 15 596 13 Commercial Commercial and industrial Automotive 47 1 32 — Other 77 8 56 1 Commercial real estate — Automotive 6 — 7 — Total commercial 130 9 95 1 Total consumer and commercial finance receivables and loans $ 758 $ 24 $ 691 $ 14
Troubled Debt Restructurings on Financing Receivables [Table Text Block]	The following tables present 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 June 30, ($ 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 5,762 $ 103 $ 88 4,767 $ 79 $ 68 Consumer mortgage Mortgage Finance — — — 2 1 1 Mortgage — Legacy 19 3 2 26 4 4 Total consumer mortgage 19 3 2 28 5 5 Total consumer 5,781 106 90 4,795 84 73 Commercial Commercial and industrial Other 1 21 21 — — — Total commercial 1 21 21 — — — Total consumer and commercial finance receivables and loans 5,782 $ 127 $ 111 4,795 $ 84 $ 73 2017 2016 Six months ended June 30, ($ 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 12,209 $ 218 $ 187 10,389 $ 168 $ 144 Consumer mortgage Mortgage Finance 1 — — 3 2 2 Mortgage — Legacy 72 15 14 57 8 8 Total consumer mortgage 73 15 14 60 10 10 Total consumer 12,282 233 201 10,449 178 154 Commercial Commercial and industrial Other 2 44 44 — — — Total commercial 2 44 44 — — — Total consumer and commercial finance receivables and loans 12,284 $ 277 $ 245 10,449 $ 178 $ 154
Finance receivables and loans redefaulted during the period [Table Text Block]	The following tables present 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 June 30, ($ in millions) Number of loans Gross carrying value Charge-off amount Number of loans Gross carrying value Charge-off amount Consumer automotive 2,143 $ 25 $ 17 1,858 $ 23 $ 13 Consumer mortgage Mortgage Finance — — — — — — Mortgage — Legacy — — — 2 — — Total consumer finance receivables and loans 2,143 $ 25 $ 17 1,860 $ 23 $ 13 2017 2016 Six months ended June 30, ($ in millions) Number of loans Gross carrying value Charge-off amount Number of loans Gross carrying value Charge-off amount Consumer automotive 4,132 $ 49 $ 33 3,658 $ 46 $ 25 Consumer mortgage Mortgage Finance 1 1 — — — — Mortgage — Legacy — — — 3 — — Total consumer finance receivables and loans 4,133 $ 50 $ 33 3,661 $ 46 $ 25

Investment in Operating Lease42

Investment in Operating Leases, Net (Tables)	6 Months Ended
	Jun. 30, 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) June 30, 2017 December 31, 2016 Vehicles $ 12,136 $ 14,584 Accumulated depreciation (2,419 ) (3,114 ) Investment in operating leases, net $ 9,717 $ 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 June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 Depreciation expense on operating lease assets (excluding remarketing gains) $ 353 $ 520 $ 739 $ 1,085 Remarketing gains (32 ) (86 ) (29 ) (141 ) Net depreciation expense on operating lease assets $ 321 $ 434 $ 710 $ 944

Securitizations and Variable 43

Securitizations and Variable Interest Entities (Tables)	6 Months Ended
	Jun. 30, 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 nonconsolidated VIEs (a) Maximum exposure to loss in nonconsolidated VIEs June 30, 2017 On-balance sheet variable interest entities Consumer automotive $ 18,495 (b) $ 7,941 (c) Commercial automotive 14,052 4,657 Off-balance sheet variable interest entities Consumer automotive 48 (d) — $ 2,662 $ 2,710 (e) Commercial other 539 (f) 229 (g) — 719 (h) Total $ 33,134 $ 12,827 $ 2,662 $ 3,429 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 $9.0 billion and $9.6 billion of assets that are not encumbered by VIE beneficial interests held by third parties at June 30, 2017 , and December 31, 2016 , respectively. Ally or consolidated affiliates hold the interests in these assets, which eliminate in consolidation. (c) Includes $87 million and $50 million of liabilities due to consolidated affiliates at June 30, 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 $46 million classified as held-to-maturity securities and $2 million classified as other assets at June 30, 2017 . Of the total amount at June 30, 2017 , $48 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 six months ended June 30, 2017 , and 2016 . Additionally, this table contains information regarding cash flows received from and paid to nonconsolidated securitization entities that existed during each period. Six months ended June 30, ($ in millions) Consumer automotive 2017 Cash proceeds from transfers completed during the period $ 1,187 Cash disbursements for repurchases during the period (a) (491 ) Servicing fees 18 Cash flows received on retained interests in securitization entities 10 Other cash flows 4 2016 Cash proceeds from transfers completed during the period $ 1,604 Servicing fees 17 Other cash flows 5
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 past due ($ in millions) June 30, 2017 December 31, 2016 June 30, 2017 December 31, 2016 On-balance sheet loans Consumer automotive $ 66,774 $ 65,793 $ 586 $ 730 Consumer mortgage 11,297 11,050 82 85 Commercial automotive 38,840 38,853 8 7 Commercial other 3,634 3,248 — — Total on-balance sheet loans 120,545 118,944 676 822 Off-balance sheet securitization entities Consumer automotive 2,662 2,392 13 13 Total off-balance sheet securitization entities 2,662 2,392 13 13 Whole-loan sales (a) 1,947 3,164 3 6 Total $ 125,154 $ 124,500 $ 692 $ 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 June 30, Six months ended June 30, ($ in millions) 2017 2016 2017 2016 On-balance sheet loans Consumer automotive $ 199 $ 148 $ 450 $ 321 Consumer mortgage — 4 2 10 Total on-balance sheet loans 199 152 452 331 Off-balance sheet securitization entities Consumer automotive 3 2 6 4 Total off-balance sheet securitization entities 3 2 6 4 Whole-loan sales (a) 1 1 2 1 Total $ 203 $ 155 $ 460 $ 336 (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)	6 Months Ended
	Jun. 30, 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) June 30, 2017 December 31, 2016 On-balance sheet automotive finance loans and leases Consumer automotive $ 66,491 $ 65,646 Commercial automotive 38,840 38,853 Operating leases 9,615 11,311 Other 67 67 Off-balance sheet automotive finance loans Securitizations 2,690 2,412 Whole-loan sales 1,964 3,191 Total serviced automotive finance loans and leases $ 119,667 $ 121,480

Other Assets (Tables)

Other Assets (Tables)	6 Months Ended
	Jun. 30, 2017
Other Assets [Abstract]
Schedule of Other Assets [Table Text Block]	The components of other assets were as follows. ($ in millions) June 30, 2017 December 31, 2016 Property and equipment at cost $ 985 $ 901 Accumulated depreciation (565 ) (525 ) Net property and equipment 420 376 Restricted cash collections for securitization trusts (a) 1,259 1,694 Nonmarketable equity investments (b) 938 1,046 Net deferred tax assets 764 994 Accrued interest and rent receivables 470 476 Goodwill (c) 240 240 Cash reserve deposits held for securitization trusts (d) 143 184 Other accounts receivable 115 100 Restricted cash and cash equivalents 113 111 Cash collateral placed with counterparties 103 167 Fair value of derivative contracts in receivable position (e) 41 95 Other assets 1,347 1,371 Total other assets $ 5,953 $ 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 $454 million and $577 million at June 30, 2017 , and December 31, 2016 , respectively; and Federal Reserve Bank (FRB) stock of $444 million and $435 million at June 30, 2017 , and December 31, 2016 , respectively. (c) Includes goodwill of $27 million at our Insurance operations at both June 30, 2017 , and December 31, 2016 ; $193 million within Corporate and Other at both June 30, 2017 , and December 31, 2016 ; and $20 million within Automotive Finance operations at both June 30, 2017 , and December 31, 2016 . No changes to the carrying amount of goodwill were recorded during the six months ended June 30, 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)	6 Months Ended
	Jun. 30, 2017
Deposits [Abstract]
Schedule of Deposit Liabilities [Table Text Block]	( $ in millions ) June 30, 2017 December 31, 2016 Noninterest-bearing deposits $ 107 $ 84 Interest-bearing deposits Savings and money market checking accounts 50,732 46,976 Certificates of deposit 35,299 31,795 Dealer deposits 45 167 Total deposit liabilities $ 86,183 $ 79,022

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
Schedule of Short-term Debt [Table Text Block]	The following table presents the composition of our short-term borrowings portfolio. June 30, 2017 December 31, 2016 ($ in millions) Unsecured Secured (a) Total Unsecured Secured (a) Total Demand notes $ 3,457 $ — $ 3,457 $ 3,622 $ — $ 3,622 Federal Home Loan Bank — 4,300 4,300 — 7,875 7,875 Financial instruments sold under agreements to repurchase — 1,706 1,706 — 1,176 1,176 Other 1,249 (b) — 1,249 — — — Total short-term borrowings $ 4,706 $ 6,006 $ 10,712 $ 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 $1 million as of June 30, 2017 . This debt is scheduled to mature in December 2017.
Schedule of Debt [Table Text Block]	The following table presents the composition of our long-term debt portfolio. June 30, 2017 December 31, 2016 ($ in millions) Unsecured Secured Total Unsecured Secured Total Long-term debt Due within one year $ 3,342 $ 8,402 $ 11,744 $ 4,274 $ 10,279 $ 14,553 Due after one year (a) 13,909 23,192 37,101 15,450 23,810 39,260 Fair value adjustment (b) 309 (9 ) 300 326 (11 ) 315 Total long-term debt (c) $ 17,560 $ 31,585 $ 49,145 $ 20,050 $ 34,078 $ 54,128 (a) Includes $2.6 billion of trust preferred securities at both June 30, 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 $6.5 billion and $6.1 billion at June 30, 2017 , and December 31, 2016 , respectively.
Scheduled Remaining Maturity of Long-term Debt [Table Text Block]	The following table presents the scheduled remaining maturity of long-term debt at June 30, 2017 , assuming no early redemptions will occur. The actual payment of secured debt may vary based on the payment activity of the related pledged assets. ($ in millions) 2017 2018 2019 2020 2021 2022 and thereafter Fair value adjustment Total Unsecured Long-term debt $ 1,792 $ 3,700 $ 1,681 $ 2,249 $ 638 $ 8,473 $ 309 $ 18,842 Original issue discount (47 ) (100 ) (39 ) (39 ) (43 ) (1,014 ) — (1,282 ) Total unsecured 1,745 3,600 1,642 2,210 595 7,459 309 17,560 Secured Long-term debt 4,824 7,928 8,610 6,109 2,566 1,557 (9 ) 31,585 Total long-term debt $ 6,569 $ 11,528 $ 10,252 $ 8,319 $ 3,161 $ 9,016 $ 300 $ 49,145
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. June 30, 2017 December 31, 2016 ($ in millions) Total (a) Ally Bank Total (a) Ally Bank Investment securities (b) $ 3,260 $ 1,896 $ 4,895 $ 4,231 Mortgage assets held-for-investment and lending receivables 11,193 11,193 10,954 10,954 Consumer automotive finance receivables (b) 25,658 4,421 27,846 5,751 Commercial automotive finance receivables 17,883 17,733 19,487 19,280 Investment in operating leases, net 956 28 2,040 913 Total assets restricted as collateral (c) (d) $ 58,950 $ 35,271 $ 65,222 $ 41,129 Secured debt $ 37,591 (e) $ 17,194 $ 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 $17.1 billion and $19.0 billion at June 30, 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 FRB Discount Window. Ally Bank had assets pledged and restricted as collateral to the FRB totaling $2.4 billion at both June 30, 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 $6.0 billion and $9.1 billion of short-term borrowings at June 30, 2017 , and December 31, 2016 , respectively.
Schedule Of Committed Funding Facilities [Table Text Block]	Committed Funding Facilities Outstanding Unused capacity (a) Total capacity ($ in millions) June 30, 2017 December 31, 2016 June 30, 2017 December 31, 2016 June 30, 2017 December 31, 2016 Bank funding Secured (b) $ 1,750 $ 3,250 $ 250 $ 350 $ 2,000 $ 3,600 Parent funding Secured 10,880 11,550 2,295 1,975 13,175 13,525 Unsecured 1,250 — — 1,250 1,250 1,250 Total committed facilities $ 13,880 $ 14,800 $ 2,545 $ 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 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)	6 Months Ended
	Jun. 30, 2017
Accounts Payable and Accrued Liabilities [Abstract]
Schedule of Accrued Liabilities [Table Text Block]	( $ in millions ) June 30, 2017 December 31, 2016 Accounts payable $ 871 $ 649 Employee compensation and benefits 182 232 Reserves for insurance losses and loss adjustment expenses 179 149 Fair value of derivative contracts in payable position (a) 43 95 Deferred revenue 40 56 Cash collateral received from counterparties 6 10 Other liabilities 571 546 Total accrued expenses and other liabilities $ 1,892 $ 1,737 (a) For additional information on derivative instruments and hedging activities, refer to Note 19 .

Accumulated Other Comprehensi49

Accumulated Other Comprehensive (Loss) Income (Tables)	6 Months Ended
	Jun. 30, 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) income. ($ in millions) Unrealized gains on investment securities (a) Translation adjustments and net investment hedges (b) Cash flow hedges (b) Defined benefit pension plans Accumulated other comprehensive (loss) income Balance at December 31, 2015 $ (159 ) $ 9 $ 8 $ (89 ) $ (231 ) 2016 net change 262 5 — (1 ) 266 Balance at June 30, 2016 $ 103 $ 14 $ 8 $ (90 ) $ 35 Balance at December 31, 2016 $ (273 ) $ 14 $ 8 $ (90 ) $ (341 ) 2017 net change 96 — 1 (1 ) 96 Balance at June 30, 2017 $ (177 ) $ 14 $ 9 $ (91 ) $ (245 ) (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) income. Three months ended June 30, 2017 ($ in millions) Before tax Tax effect After tax Investment securities Net unrealized gains arising during the period $ 132 $ (37 ) $ 95 Less: Net realized gains reclassified to income from continuing operations 23 (a) (3 ) (b) 20 Net change 109 (34 ) 75 Translation adjustments Net unrealized gains arising during the period 4 (1 ) 3 Net investment hedges (c) Net unrealized losses arising during the period (4 ) 1 (3 ) Cash flow hedges (c) Net unrealized gains arising during the period 1 — 1 Other comprehensive income $ 110 $ (34 ) $ 76 (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 June 30, 2016 ($ in millions) Before tax Tax effect After tax Investment securities Net unrealized gains arising during the period $ 185 $ (25 ) $ 160 Less: Net realized gains reclassified to income from continuing operations 39 (a) 1 (b) 40 Net change 146 (26 ) 120 Translation adjustments Net unrealized losses arising during the period (1 ) — (1 ) Less: Net realized losses reclassified to income from discontinued operations, net of tax (1 ) — (1 ) Net change — — — Other comprehensive income $ 146 $ (26 ) $ 120 (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 . Six months ended June 30, 2017 ($ in millions) Before tax Tax effect After tax Investment securities Net unrealized gains arising during the period $ 183 $ (42 ) $ 141 Less: Net realized gains reclassified to income from continuing operations 50 (a) (5 ) (b) 45 Net change 133 (37 ) 96 Translation adjustments Net unrealized gains arising during the period 6 (2 ) 4 Net investment hedges (c) Net unrealized losses arising during the period (6 ) 2 (4 ) Cash flow hedges (c) Net unrealized gains arising during the period 1 — 1 Defined benefit pension plans Net unrealized losses arising during the period (1 ) — (1 ) Other comprehensive income $ 133 $ (37 ) $ 96 (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 . Six months ended June 30, 2016 ($ in millions) Before Tax Tax Effect After Tax Investment securities Net unrealized gains arising during the period $ 465 $ (129 ) $ 336 Less: Net realized gains reclassified to income from continuing operations 93 (a) (19 ) (b) 74 Net change 372 (110 ) 262 Translation adjustments Net unrealized gains arising during the period 12 (5 ) 7 Less: Net realized losses reclassified to income from discontinued operations, net of tax (1 ) — (1 ) Net change 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 $ 378 $ (112 ) $ 266 (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)	6 Months Ended
	Jun. 30, 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 June 30, Six months ended June 30, ( $ in millions, except per share data; shares in thousands ) (a) 2017 2016 2017 2016 Net income from continuing operations $ 254 $ 357 $ 467 $ 604 Preferred stock dividends — (15 ) — (30 ) Net income from continuing operations attributable to common shareholders 254 342 467 574 (Loss) income from discontinued operations, net of tax (2 ) 3 (1 ) 6 Net income attributable to common shareholders $ 252 $ 345 $ 466 $ 580 Basic weighted-average common shares outstanding (b) 457,891 485,370 461,904 484,802 Diluted weighted-average common shares outstanding (b) 458,819 486,074 462,802 485,364 Basic earnings per common share Net income from continuing operations $ 0.55 $ 0.70 $ 1.01 $ 1.18 (Loss) income from discontinued operations, net of tax (0.01 ) 0.01 — 0.01 Net income $ 0.55 $ 0.71 $ 1.01 $ 1.20 Diluted earnings per common share Net income from continuing operations $ 0.55 $ 0.70 $ 1.01 $ 1.18 (Loss) income from discontinued operations, net of tax (0.01 ) 0.01 — 0.01 Net income $ 0.55 $ 0.71 $ 1.01 $ 1.19 (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 and six months ended June 30, 2017 , and 2016 .

Regulatory Capital and Other 51

Regulatory Capital and Other Regulatory Matters (Tables)	6 Months Ended
	Jun. 30, 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. June 30, 2017 December 31, 2016 Required minimum Well-capitalized minimum ( $ in millions ) Amount Ratio Amount Ratio Capital ratios Common Equity Tier 1 (to risk-weighted assets) Ally Financial Inc. $ 13,066 9.47 % $ 12,978 9.37 % 4.50 % (a) Ally Bank 18,975 17.89 17,888 16.70 4.50 6.50 % Tier 1 (to risk-weighted assets) Ally Financial Inc. $ 15,417 11.18 % $ 15,147 10.93 % 6.00 % 6.00 % Ally Bank 18,975 17.89 17,888 16.70 6.00 8.00 Total (to risk-weighted assets) Ally Financial Inc. $ 17,704 12.83 % $ 17,419 12.57 % 8.00 % 10.00 % Ally Bank 19,651 18.53 18,458 17.24 8.00 10.00 Tier 1 leverage (to adjusted quarterly average assets) (b) Ally Financial Inc. $ 15,417 9.51 % $ 15,147 9.54 % 4.00 % (a) Ally Bank 18,975 15.31 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)	6 Months Ended
	Jun. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value Amounts of Derivative Instruments Reported On Our Condensed Consolidated Balance Sheet [Table Text Block]	sentation 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. June 30, 2017 December 31, 2016 Derivative contracts in a Notional amount Derivative contracts in a Notional amount ($ in millions) receivable position (a) payable position (b) receivable position (a) payable position (b) Derivatives designated as accounting hedges Interest rate contracts Swaps (c) (d) (e) (f) (g) $ — $ — $ 4,225 $ 19 $ 21 $ 4,731 Foreign exchange contracts Forwards — 3 154 1 — 171 Total derivatives designated as accounting hedges — 3 4,379 20 21 4,902 Derivatives not designated as accounting hedges Interest rate contracts Swaps — — 15 — — 137 Futures and forwards — — 103 — — — Written options 1 39 12,449 — 73 14,518 Purchased options 39 — 12,346 73 — 14,517 Total interest rate risk 40 39 24,913 73 73 29,172 Foreign exchange contracts Futures and forwards 1 1 142 1 — 92 Total foreign exchange risk 1 1 142 1 — 92 Equity contracts Written options — — — — 1 — Purchased options — — — 1 — — Total equity risk — — — 1 1 — Total derivatives not designated as accounting hedges 41 40 25,055 75 74 29,264 Total derivatives $ 41 $ 43 $ 29,434 $ 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 $0 million and $7 million at June 30, 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 June 30, 2017 , and December 31, 2016 , respectively. (c) Includes fair value hedges consisting of receive-fixed swaps on fixed-rate unsecured debt obligations with $0 million and $8 million in a receivable position, $0 million and $14 million in a payable position, and a $3.3 billion and $1.7 billion notional amount at June 30, 2017 , and December 31, 2016 , respectively. The hedge notional amount of $3.3 billion at June 30, 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 $240 million notional amount at both June 30, 2017 , and December 31, 2016 . (e) Other fair value hedges include pay-fixed swaps on portfolios of held-for-investment automotive loan assets with $0 million and $10 million in a receivable position, $0 million and $1 million in a payable position, and a $0.0 billion and $2.8 billion notional amount at June 30, 2017 , and December 31, 2016 , res
Gains and Losses On Derivative Instruments Reported in Statement of Comprehensive Income [Table Text Block]	sentation 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 June 30, Six months ended June 30, ( $ in millions ) 2017 2016 2017 2016 Derivatives qualifying for hedge accounting (Loss) gain recognized in earnings on derivatives Interest rate contracts Interest and fees on finance receivables and loans (a) $ (1 ) $ (6 ) $ 1 $ (34 ) Interest on long-term debt (b) 20 51 24 242 Gain (loss) recognized in earnings on hedged items Interest rate contracts Interest and fees on finance receivables and loans (c) 1 5 (3 ) 33 Interest on long-term debt (d) (20 ) (50 ) (23 ) (246 ) Total derivatives qualifying for hedge accounting — — (1 ) (5 ) Derivatives not designated as accounting hedges (Loss) gain recognized in earnings on derivatives Interest rate contracts Gain on mortgage and automotive loans, net 1 — 1 — Other income, net of losses (1 ) 1 (3 ) 3 Total interest rate contracts — 1 (2 ) 3 Foreign exchange contracts (e) Interest on long-term debt — (1 ) — (2 ) Other income, net of losses (3 ) 1 (4 ) (3 ) Total foreign exchange contracts (3 ) — (4 ) (5 ) Equity contracts Compensation and benefits expense — (1 ) — (2 ) Total equity contracts — (1 ) — (2 ) Loss recognized in earnings on derivatives $ (3 ) $ — $ (7 ) $ (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 $0 million and $5 million for the three months ended June 30, 2017 , and 2016 , respectively, and $1 million and $12 million for the six months ended June 30, 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 $7 million and $11 million for the three months ended June 30, 2017 , and 2016, respectively, and $12 million and $27 million for the six months ended June 30, 2017 , and 2016 , respectively. Amounts also 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 $2 million for the three months ended June 30, 2017 , and 2016, respectively, and $0 million and $3 million for the six months ended June 30, 2017 , and 2016 , respectively. (c) Amounts exclude losses related to amortization of deferred loan basis adjustments on the de-designated hedged item of $6 million and $4 million for the three months ended June 30, 2017 , and 2016 , respectively, and $11 million and $9 million for the six months ended June 30, 2017 , and 2016 , respectively. (d) Amounts exclude gains related to amortization of deferred debt basis adjustments on the de-designated hedged item of $20 million and $21 million for the three months ended June 30, 2017 , and 2016 , respectively, and $40 million and $39 million for the six months ended June 30, 2017 , and 2016 , respectively. Amounts also 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 June 30, 2017 , and 2016 , respectively, and $1 million and $0 million for the six months ended June 30, 2017 , and 2016 , respectively. (e) Amounts exclude gains and losses related to the revaluation of the related foreign-denominated debt or receivable. Losses of $4 million and $1 million were recognized for the three months ended June 30, 2017 , and 2016 , respectively, and gains of $5 million and $3 million were recognized for the six months ended June 30, 2017 , and 2016 , res
Derivative Instruments Used in Cash Flow and Net Investment Hedge Accounting Relationships [Table Text Block]	ectively. In connection with derivative instruments used in cash flow and net investment hedge accounting relationships, losses of $4 million and $0 million were recognized in other comprehensive income for the three months ended June 30, 2017 , and 2016 , respectively, and losses of $6 million were recognized in other comprehensive income for both the six months ended June 30, 2017 , and 2016 . 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 $4 million and $0 million for the three months ended June 30, 2017 , and 2016, respectively, and $7 million and $11 million for the six months ended June 30, 2017, and 2016.

Fair Value (Tables)

Fair Value (Tables)	6 Months Ended
	Jun. 30, 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 June 30, 2017 ($ in millions) Level 1 Level 2 Level 3 Total Assets Investment securities Available-for-sale securities Debt securities U.S. Treasury $ 1,852 $ — $ — $ 1,852 U.S. States and political subdivisions — 782 — 782 Foreign government 7 143 — 150 Agency mortgage-backed residential — 13,676 — 13,676 Mortgage-backed residential — 2,038 — 2,038 Mortgage-backed commercial — 475 — 475 Asset-backed — 1,014 — 1,014 Corporate debt — 1,272 — 1,272 Total debt securities 1,859 19,400 — 21,259 Equity securities (a) 505 — — 505 Total available-for-sale securities 2,364 19,400 — 21,764 Mortgage loans held-for-sale — — 3 3 Interests retained in financial asset sales — — 5 5 Derivative contracts in a receivable position (b) Interest rate — 39 1 40 Foreign currency — 1 — 1 Total derivative contracts in a receivable position — 40 1 41 Total assets $ 2,364 $ 19,440 $ 9 $ 21,813 Liabilities Accrued expenses and other liabilities Derivative contracts in a payable position (b) Interest rate $ — $ (39 ) $ — $ (39 ) Foreign currency — (4 ) — (4 ) Total derivative contracts in a payable position — (43 ) — (43 ) Total liabilities $ — $ (43 ) $ — $ (43 ) (a) Our investment in any one industry did not exceed 18% . (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
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 gains Fair value at June 30, 2017 Net unrealized gains included in earnings still held at June 30, 2017 ($ in millions) Fair value at April 1, 2017 included in earnings included in OCI Purchases Sales Issuances Settlements Assets Mortgage loans held-for-sale $ 1 $ — $ — $ 20 $ (18 ) $ — $ — $ 3 $ — Other assets Interests retained in financial asset sales 31 1 — — 4 — (31 ) 5 — Derivative assets — 1 — — — — — 1 1 Total assets $ 32 $ 2 $ — $ 20 $ (14 ) $ — $ (31 ) $ 9 $ 1 Level 3 recurring fair value measurements Fair value at April 1, 2016 Net realized/unrealized gains Purchases Sales Issuances Settlements Fair value at June 30, 2016 Net unrealized gains included in earnings still held at June 30, 2016 ($ in millions) included in earnings included in OCI Assets Other assets Interests retained in financial asset sales $ 31 $ 1 (a) $ — $ — $ 2 $ — $ (3 ) $ 31 $ — Total assets $ 31 $ 1 $ — $ — $ 2 $ — $ (3 ) $ 31 $ — (a) Reported as other income, net of losses, in the Condensed Consolidated Statement of Comprehensive Income . Level 3 recurring fair value measurements Net realized/unrealized gains Fair value at June 30, 2017 Net unrealized gains included in earnings still held at June 30, 2017 ($ in millions) Fair value at Jan. 1, 2017 included in earnings included in OCI Purchases Sales Issuances Settlements Assets Mortgage loans held-for-sale $ — $ — $ — $ 23 $ (20 ) $ — $ — $ 3 $ — Other assets Interests retained in financial asset sales 29 1 — — 8 — (33 ) 5 — Derivative assets — 1 — — — — — 1 1 Total assets $ 29 $ 2 $ — $ 23 $ (12 ) $ — $ (33 ) $ 9 $ 1 Level 3 recurring fair value measurements Fair value at Jan. 1, 2016 Net realized/unrealized gains Purchases Sales Issuances Settlements Fair value at June 30, 2016 Net unrealized gains included in earnings still held at June 30, 2016 ($ in millions) included in earnings included in OCI Assets Other assets Interests retained in financial asset sales $ 40 $ 3 (a) $ — $ — $ 6 $ — $ (18 ) $ 31 $ — Total assets $ 40 $ 3 $ — $ — $ 6 $ — $ (18 ) $ 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 fair value measurements Lower-of-cost or fair value or valuation reserve allowance Total gain (loss) included in earnings for the three months ended Total gain (loss) included in earnings for the six months ended June 30, 2017 ($ in millions) Level 1 Level 2 Level 3 Total Assets Loans held-for-sale, net $ — $ — $ 13 $ 13 $ — n/m (a) n/m (a) Commercial finance receivables and loans, net (b) Commercial and industrial Automotive — — 45 45 $ (6 ) n/m (a) n/m (a) Other — — 34 34 (25 ) n/m (a) n/m (a) Total commercial finance receivables and loans, net — — 79 79 (31 ) n/m (a) n/m (a) Other assets Repossessed and foreclosed assets (c) — — 13 13 (1 ) n/m (a) n/m (a) Other — — 4 4 — n/m (a) n/m (a) Total assets $ — $ — $ 109 $ 109 $ (32 ) n/m 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 2017. 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. Nonrecurring fair value measurements Lower-of-cost or fair value or valuation reserve allowance Total gain included in earnings for the three months ended Total gain included in earnings for the six months ended June 30, 2016 ($ in millions) Level 1 Level 2 Level 3 Total Assets Loans held-for-sale, net $ — $ — $ 15 $ 15 $ — n/m (a) n/m (a) Commercial finance receivables and loans, net (b) Commercial and industrial Automotive — — 43 43 (6 ) n/m (a) n/m (a) Other — — 46 46 (18 ) n/m (a) n/m (a) Total commercial finance receivables and loans, net — — 89 89 (24 ) n/m (a) n/m (a) Other assets Repossessed and foreclosed assets (c) — — 10 10 (3 ) n/m (a) n/m (a) Other — — 5 5 — n/m (a) n/m (a) Total assets $ — $ — $ 119 $ 119 $ (27 ) n/m 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 June 30, 2017 , and December 31, 2016 . Estimated fair value ($ in millions) Carrying value Level 1 Level 2 Level 3 Total June 30, 2017 Financial assets Held-to-maturity securities $ 1,189 $ — $ 1,156 $ — $ 1,156 Loans held-for-sale, net 17 — — 17 17 Finance receivables and loans, net 119,303 — — 121,029 121,029 Nonmarketable equity investments (a) 925 — 898 25 923 Financial liabilities Deposit liabilities $ 86,183 $ — $ — $ 84,287 $ 84,287 Short-term borrowings 10,712 — — 10,714 10,714 Long-term debt 49,145 — 32,371 19,163 51,534 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 (a) Excludes investments with a carrying value of $13 million and fair value of $34 million at June 30, 2017, for which fair value is measured at net asset value (or its equivalent) as a practical expedient. 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)	6 Months Ended
	Jun. 30, 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) presented in the Condensed Consolidated Balance Sheet Gross amounts not offset in the Condensed Consolidated Balance Sheet June 30, 2017 ($ in millions) Financial instruments Collateral (a) (b) (c) Net amount Assets Derivative assets in net asset positions $ 39 $ — $ 39 $ — $ — $ 39 Derivative assets in net liability positions 1 — 1 (1 ) — — Derivative assets with no offsetting arrangements 1 — 1 — — 1 Total assets (d) $ 41 $ — $ 41 $ (1 ) $ — $ 40 Liabilities Derivative liabilities in net liability positions $ (43 ) $ — $ (43 ) $ — $ 4 $ (39 ) Derivative liabilities in net asset positions — — — — — — Total derivative liabilities (d) (43 ) — (43 ) — 4 (39 ) Securities sold under agreements to repurchase (e) (1,322 ) — (1,322 ) — 1,322 — Total liabilities $ (1,365 ) $ — $ (1,365 ) $ — $ 1,326 $ (39 ) (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. $3 million of noncash derivative collateral pledged to us was excluded at June 30, 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 $3 million at June 30, 2017 . We have not sold or pledged any of the noncash collateral received under these agreements as of June 30, 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) presented in the Condensed Consolidated Balance Sheet Gross amounts not offset in the Condensed Consolidated Balance Sheet December 31, 2016 ( $ in millions ) Financial instruments Collateral (a) (b) (c) 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)	6 Months Ended
	Jun. 30, 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) presented in the Condensed Consolidated Balance Sheet Gross amounts not offset in the Condensed Consolidated Balance Sheet June 30, 2017 ($ in millions) Financial instruments Collateral (a) (b) (c) Net amount Assets Derivative assets in net asset positions $ 39 $ — $ 39 $ — $ — $ 39 Derivative assets in net liability positions 1 — 1 (1 ) — — Derivative assets with no offsetting arrangements 1 — 1 — — 1 Total assets (d) $ 41 $ — $ 41 $ (1 ) $ — $ 40 Liabilities Derivative liabilities in net liability positions $ (43 ) $ — $ (43 ) $ — $ 4 $ (39 ) Derivative liabilities in net asset positions — — — — — — Total derivative liabilities (d) (43 ) — (43 ) — 4 (39 ) Securities sold under agreements to repurchase (e) (1,322 ) — (1,322 ) — 1,322 — Total liabilities $ (1,365 ) $ — $ (1,365 ) $ — $ 1,326 $ (39 ) (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. $3 million of noncash derivative collateral pledged to us was excluded at June 30, 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 $3 million at June 30, 2017 . We have not sold or pledged any of the noncash collateral received under these agreements as of June 30, 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) presented in the Condensed Consolidated Balance Sheet Gross amounts not offset in the Condensed Consolidated Balance Sheet December 31, 2016 ( $ in millions ) Financial instruments Collateral (a) (b) (c) 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)	6 Months Ended
	Jun. 30, 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 June 30, ($ 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 $ 932 $ 14 $ 32 $ 48 $ 41 $ 1,067 Other revenue 107 245 1 10 25 388 Total net revenue 1,039 259 33 58 66 1,455 Provision for loan losses 266 — 1 6 (4 ) 269 Total noninterest expense 426 280 25 17 62 810 Income (loss) from continuing operations before income tax expense $ 347 $ (21 ) $ 7 $ 35 $ 8 $ 376 Total assets $ 115,447 $ 7,308 $ 8,902 $ 3,552 $ 29,136 $ 164,345 2016 Net financing revenue and other interest income (loss) $ 929 $ 16 $ 26 $ 29 $ (16 ) $ 984 Other revenue 77 259 — 4 34 374 Total net revenue 1,006 275 26 33 18 1,358 Provision for loan losses 170 — — 3 (1 ) 172 Total noninterest expense 410 293 17 16 37 773 Income (loss) from continuing operations before income tax expense $ 426 $ (18 ) $ 9 $ 14 $ (18 ) $ 413 Total assets $ 112,356 $ 7,193 $ 8,014 $ 2,989 $ 27,379 $ 157,931 (a) Net financing revenue and other interest income after the provision for loan losses totaled $798 million and $812 million for the three months ended June 30, 2017 , and 2016 , respectively. Six months ended June 30, ($ 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 $ 1,824 $ 29 $ 66 $ 82 $ 45 $ 2,046 Other revenue 208 509 1 28 38 784 Total net revenue 2,032 538 67 110 83 2,830 Provision for loan losses 534 — 2 12 (8 ) 540 Total noninterest expense 863 519 49 38 119 1,588 Income (loss) from continuing operations before income tax expense $ 635 $ 19 $ 16 $ 60 $ (28 ) $ 702 Total assets $ 115,447 $ 7,308 $ 8,902 $ 3,552 $ 29,136 $ 164,345 2016 Net financing revenue and other interest income (loss) $ 1,825 $ 30 $ 46 $ 57 $ (23 ) $ 1,935 Other revenue 154 513 — 10 73 750 Total net revenue 1,979 543 46 67 50 2,685 Provision for loan losses 379 — 3 9 1 392 Total noninterest expense 837 511 32 33 70 1,483 Income (loss) from continuing operations before income tax expense $ 763 $ 32 $ 11 $ 25 $ (21 ) $ 810 Total assets $ 112,356 $ 7,193 $ 8,014 $ 2,989 $ 27,379 $ 157,931 (a) Net financing revenue and other interest income after the provision for loan losses totaled $1,506 million and $1,543 million for the six months ended June 30, 2017 , and 2016 , respectively.

Parent and Guarantor Condense57

Parent and Guarantor Condensed Consolidating Financial Statements (Tables)	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Condensed Income Statement [Table Text Block]	Condensed Consolidating Statements of Comprehensive Income Three months ended June 30, 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 ) $ — $ 1,482 $ — $ 1,447 Interest and fees on finance receivables and loans — intercompany 3 — 2 (5 ) — Interest and dividends on investment securities and other earning assets — — 146 — 146 Interest on cash and cash equivalents 2 — 5 — 7 Interest-bearing cash — intercompany — — 2 (2 ) — Operating leases 3 — 485 — 488 Total financing (loss) revenue and other interest income (27 ) — 2,122 (7 ) 2,088 Interest expense Interest on deposits 1 — 249 — 250 Interest on short-term borrowings 19 — 14 — 33 Interest on long-term debt 274 — 143 — 417 Interest on intercompany debt 4 — 3 (7 ) — Total interest expense 298 — 409 (7 ) 700 Net depreciation expense on operating lease assets 3 — 318 — 321 Net financing revenue (328 ) — 1,395 — 1,067 Cash dividends from subsidiaries Nonbank subsidiaries 387 — — (387 ) — Other revenue Insurance premiums and service revenue earned — — 227 — 227 Gain on mortgage and automotive loans, net 32 — 4 — 36 Loss on extinguishment of debt — — (1 ) — (1 ) Other gain on investments, net — — 23 — 23 Other income, net of losses 163 — 211 (271 ) 103 Total other revenue 195 — 464 (271 ) 388 Total net revenue 254 — 1,859 (658 ) 1,455 Provision for loan losses 82 — 187 — 269 Noninterest expense Compensation and benefits expense 19 — 246 — 265 Insurance losses and loss adjustment expenses — — 125 — 125 Other operating expenses 213 — 478 (271 ) 420 Total noninterest expense 232 — 849 (271 ) 810 (Loss) income from continuing operations before income tax (benefit) expense and undistributed income (loss) of subsidiaries (60 ) — 823 (387 ) 376 Income tax (benefit) expense from continuing operations (93 ) — 215 — 122 Net income from continuing operations 33 — 608 (387 ) 254 Loss from discontinued operations, net of tax — — (2 ) — (2 ) Undistributed income (loss) of subsidiaries Bank subsidiary 375 375 — (750 ) — Nonbank subsidiaries (156 ) — — 156 — Net income 252 375 606 (981 ) 252 Other comprehensive income, net of tax 76 50 72 (122 ) 76 Comprehensive income $ 328 $ 425 $ 678 $ (1,103 ) $ 328 Three months ended June 30, 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 $ (28 ) $ — $ 1,293 $ — $ 1,265 Interest and fees on finance receivables and loans — intercompany 3 — 2 (5 ) — Interest and dividends on investment securities and other earning assets — — 99 — 99 Interest on cash and cash equivalents 1 — 3 — 4 Interest-bearing cash — intercompany — — 2 (2 ) — Operating leases 5 — 696 — 701 Total financing (loss) revenue and other interest income (19 ) — 2,095 (7 ) 2,069 Interest expense Interest on deposits 2 — 201 — 203 Interest on short-term borrowings 10 — 2 — 12 Interest on long-term debt 290 — 146 — 436 Interest on intercompany debt 4 — 3 (7 ) — Total interest expense 306 — 352 (7 ) 651 Net depreciation expense on operating lease assets 3 — 431 — 434 Net financing revenue (328 ) — 1,312 — 984 Cash dividends from subsidiaries Nonbank subsidiaries 148 — — (148 ) — Other revenue Insurance premiums and service revenue earned — — 236 — 236 (Loss) gain on mortgage and automotive loans, net (2 ) — 5 — 3 Other gain on investments, net — — 39 — 39 Other income, net of losses 317 — 214 (435 ) 96 Total other revenue 315 — 494 (435 ) 374 Total net revenue 135 — 1,806 (583 ) 1,358 Provision for loan losses 88 — 84 — 172 Noninterest expense Compensation and benefits expense 139 — 103 — 242 Insurance losses and loss adjustment expenses — — 145 — 145 Other operating expenses 317 — 502 (433 ) 386 Total noninterest expense 456 — 750 (433 ) 773 (Loss) income from continuing operations before income tax (benefit) expense and undistributed income (loss) of subsidiaries (409 ) — 972 (150 ) 413 Income tax (benefit) expense from continuing operations (65 ) (82 ) 203 — 56 Net (loss) income from continuing operations (344 ) 82 769 (150 ) 357 Income from discontinued operations, net of tax 3 — — — 3 Undistributed income (loss) of subsidiaries Bank subsidiary 336 336 — (672 ) — Nonbank subsidiaries 365 (2 ) — (363 ) — Net income 360 416 769 (1,185 ) 360 Other comprehensive income, net of tax 120 62 91 (153 ) 120 Comprehensive income $ 480 $ 478 $ 860 $ (1,338 ) $ 480 Six months ended June 30, 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 $ (70 ) $ — $ 2,885 $ — $ 2,815 Interest and fees on finance receivables and loans — intercompany 7 — 4 (11 ) — Interest and dividends on investment securities and other earning assets — — 281 (1 ) 280 Interest on cash and cash equivalents 4 — 8 — 12 Interest-bearing cash — intercompany — — 3 (3 ) — Operating leases 6 — 1,025 — 1,031 Total financing (loss) revenue and other interest income (53 ) — 4,206 (15 ) 4,138 Interest expense Interest on deposits 2 — 479 — 481 Interest on short-term borrowings 36 — 24 — 60 Interest on long-term debt 556 — 285 — 841 Interest on intercompany debt 8 — 7 (15 ) — Total interest expense 602 — 795 (15 ) 1,382 Net depreciation expense on operating lease assets 5 — 705 — 710 Net financing revenue (660 ) — 2,706 — 2,046 Cash dividends from subsidiaries Nonbank subsidiaries 427 — — (427 ) — Other revenue Insurance premiums and service revenue earned — — 468 — 468 Gain on mortgage and automotive loans, net 30 — 20 — 50 Loss on extinguishment of debt — — (2 ) — (2 ) Other gain on investments, net — — 50 — 50 Other income, net of losses 431 — 435 (648 ) 218 Total other revenue 461 — 971 (648 ) 784 Total net revenue 228 — 3,677 (1,075 ) 2,830 Provision for loan losses 189 — 351 — 540 Noninterest expense Compensation and benefits expense 140 — 410 — 550 Insurance losses and loss adjustment expenses — — 213 — 213 Other operating expenses 501 — 972 (648 ) 825 Total noninterest expense 641 — 1,595 (648 ) 1,588 (Loss) income from continuing operations before income tax (benefit) expense and undistributed income of subsidiaries (602 ) — 1,731 (427 ) 702 Income tax (benefit) expense from continuing operations (227 ) — 462 — 235 Net (loss) income from continuing operations (375 ) — 1,269 (427 ) 467 Income (loss) from discontinued operations, net of tax 2 — (3 ) — (1 ) Undistributed income of subsidiaries Bank subsidiary 764 764 — (1,528 ) — Nonbank subsidiaries 75 — — (75 ) — Net income 466 764 1,266 (2,030 ) 466 Other comprehensive income, net of tax 96 55 91 (146 ) 96 Comprehensive income $ 562 $ 819 $ 1,357 $ (2,176 ) $ 562 Six months ended June 30, 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 $ (66 ) $ — $ 2,566 $ — $ 2,500 Interest and fees on finance receivables and loans — intercompany 6 — 4 (10 ) — Interest and dividends on investment securities and other earning assets — — 201 — 201 Interest on cash and cash equivalents 2 — 5 — 7 Interest-bearing cash — intercompany — — 5 (5 ) — Operating leases 10 — 1,460 — 1,470 Total financing (loss) revenue and other interest income (48 ) — 4,241 (15 ) 4,178 Interest expense Interest on deposits 4 — 392 — 396 Interest on short-term borrowings 20 — 5 — 25 Interest on long-term debt 578 — 300 — 878 Interest on intercompany debt 9 — 6 (15 ) — Total interest expense 611 — 703 (15 ) 1,299 Net depreciation expense on operating lease assets 7 — 937 — 944 Net financing revenue (666 ) — 2,601 — 1,935 Cash dividends from subsidiaries Nonbank subsidiaries 629 — — (629 ) — Other revenue Insurance premiums and service revenue earned — — 466 — 466 (Loss) gain on mortgage and automotive loans, net (5 ) — 9 — 4 Loss on extinguishment of debt (2 ) — (2 ) — (4 ) Other gain on investments, net — — 93 — 93 Other income, net of losses 690 — 430 (929 ) 191 Total other revenue 683 — 996 (929 ) 750 Total net revenue 646 — 3,597 (1,558 ) 2,685 Provision for loan losses 148 — 244 — 392 Noninterest expense Compensation and benefits expense 286 — 208 — 494 Insurance losses and loss adjustment expenses — — 218 — 218 Other operating expenses 656 — 1,044 (929 ) 771 Total noninterest expense 942 — 1,470 (929 ) 1,483 (Loss) income from continuing operations before income tax (benefit) expense and undistributed income (loss) of subsidiaries (444 ) — 1,883 (629 ) 810 Income tax (benefit) expense from continuing operations (108 ) (82 ) 396 — 206 Net (loss) income from continuing operations (336 ) 82 1,487 (629 ) 604 Income (loss) from discontinued operations, net of tax 9 — (3 ) — 6 Undistributed income (loss) of subsidiaries Bank subsidiary 607 607 — (1,214 ) — Nonbank subsidiaries 330 (2 ) — (328 ) — Net income 610 687 1,484 (2,171 ) 610 Other comprehensive income, net of tax 266 145 243 (388 ) 266 Comprehensive income $ 876 $ 832 $ 1,727 $ (2,559 ) $ 876
Condensed Balance Sheet [Table Text Block]	Condensed Consolidating Balance Sheet June 30, 2017 ($ in millions) Parent (a) Guarantors Nonguarantors (a) Consolidating adjustments Ally consolidated Assets Cash and cash equivalents Noninterest-bearing $ 591 $ — $ 923 $ — $ 1,514 Interest-bearing 850 — 2,013 — 2,863 Interest-bearing — intercompany — — 557 (557 ) — Total cash and cash equivalents 1,441 — 3,493 (557 ) 4,377 Available-for-sale securities 6 — 21,764 (6 ) 21,764 Held-to-maturity securities — — 1,284 (95 ) 1,189 Loans held-for-sale, net — — 17 — 17 Finance receivables and loans, net Finance receivables and loans, net 5,733 — 114,795 — 120,528 Intercompany loans to Bank subsidiary 250 — — (250 ) — Nonbank subsidiaries 833 — 380 (1,213 ) — Allowance for loan losses (144 ) — (1,081 ) — (1,225 ) Total finance receivables and loans, net 6,672 — 114,094 (1,463 ) 119,303 Investment in operating leases, net 29 — 9,688 — 9,717 Intercompany receivables from Bank subsidiary 85 — — (85 ) — Nonbank subsidiaries 50 — 145 (195 ) — Investment in subsidiaries Bank subsidiary 18,869 18,869 — (37,738 ) — Nonbank subsidiaries 10,023 — — (10,023 ) — Premiums receivable and other insurance assets — — 2,055 (30 ) 2,025 Other assets 3,482 — 4,684 (2,213 ) 5,953 Total assets $ 40,657 $ 18,869 $ 157,224 $ (52,405 ) $ 164,345 Liabilities Deposit liabilities Noninterest-bearing $ — $ — $ 107 $ — $ 107 Interest-bearing 45 — 86,031 — 86,076 Total deposit liabilities 45 — 86,138 — 86,183 Short-term borrowings 4,706 — 6,006 — 10,712 Long-term debt 20,755 — 28,390 — 49,145 Intercompany debt to Bank subsidiary 95 — — (95 ) — Nonbank subsidiaries 937 — 1,089 (2,026 ) — Intercompany payables to Bank subsidiary 1 — — (1 ) — Nonbank subsidiaries 199 — 110 (309 ) — Interest payable 192 — 207 — 399 Unearned insurance premiums and service revenue — — 2,541 — 2,541 Accrued expenses and other liabilities 254 — 3,852 (2,214 ) 1,892 Total liabilities 27,184 — 128,333 (4,645 ) 150,872 Total equity 13,473 18,869 28,891 (47,760 ) 13,473 Total liabilities and equity $ 40,657 $ 18,869 $ 157,224 $ (52,405 ) $ 164,345 (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 Six months ended June 30, 2017 ($ in millions) Parent Guarantors Nonguarantors Consolidating adjustments Ally consolidated Operating activities Net cash provided by operating activities $ 561 $ — $ 1,856 $ (347 ) $ 2,070 Investing activities Purchases of available-for-sale securities — — (5,853 ) — (5,853 ) Proceeds from sales of available-for-sale securities — — 2,162 — 2,162 Proceeds from maturities and repayments of available-for-sale securities — — 1,230 — 1,230 Purchases of held-to-maturity securities — — (313 ) — (313 ) Proceeds from maturities and repayments of held-to-maturity securities — — 17 — 17 Net change in investment securities — intercompany 1 — 269 (270 ) — Purchases of finance receivables and loans held-for-investment (35 ) — (1,782 ) — (1,817 ) Proceeds from sales of finance receivables and loans originated as held-for-investment 67 — 1,213 — 1,280 Originations and repayments of finance receivables and loans held-for-investment and other, net 1,044 — (676 ) (1,956 ) (1,588 ) Net change in loans — intercompany 1,864 — 246 (2,110 ) — Purchases of operating lease assets — — (1,965 ) — (1,965 ) Disposals of operating lease assets 4 — 3,039 — 3,043 Capital contributions to subsidiaries (824 ) — — 824 — Returns of contributed capital 838 — — (838 ) — Net change in restricted cash (45 ) — 524 (5 ) 474 Net change in nonmarketable equity investments — — 107 — 107 Other, net (26 ) — 24 (91 ) (93 ) Net cash provided by (used in) investing activities 2,888 — (1,758 ) (4,446 ) (3,316 ) Financing activities Net change in short-term borrowings — third party 1,083 — (3,045 ) — (1,962 ) Net (decrease) increase in deposits (123 ) — 7,256 — 7,133 Proceeds from issuance of long-term debt — third party 353 — 7,016 1,961 9,330 Repayments of long-term debt — third party (3,323 ) — (11,043 ) — (14,366 ) Net change in debt — intercompany (370 ) — (1,864 ) 2,234 — Repurchase of common stock (373 ) — — — (373 ) Dividends paid — third party (75 ) — — — (75 ) Dividends paid and returns of contributed capital — intercompany — — (1,266 ) 1,266 — Capital contributions from parent — — 824 (824 ) — Net cash used in financing activities (2,828 ) — (2,122 ) 4,637 (313 ) Effect of exchange-rate changes on cash and cash equivalents — — 2 — 2 Net increase (decrease) in cash and cash equivalents 621 — (2,022 ) (156 ) (1,557 ) Cash and cash equivalents at beginning of year 820 — 5,515 (401 ) 5,934 Cash and cash equivalents at June 30, $ 1,441 $ — $ 3,493 $ (557 ) $ 4,377 Six months ended June 30, 2016 ($ in millions) Parent Guarantors Nonguarantors Consolidating adjustments Ally consolidated Operating activities Net cash provided by operating activities $ 146 $ — $ 2,919 $ (629 ) $ 2,436 Investing activities Purchases of available-for-sale securities — — (8,657 ) — (8,657 ) Proceeds from sales of available-for-sale securities — — 6,584 — 6,584 Proceeds from maturities and repayments of available-for-sale securities — — 1,536 — 1,536 Purchases of held-to-maturity securities — — (571 ) — (571 ) Purchases of finance receivables and loans held-for-investment — — (2,442 ) — (2,442 ) Proceeds from sales of finance receivables and loans originated as held-for-investment — — 4,156 — 4,156 Originations and repayments of finance receivables and loans held-for-investment and other (834 ) — (2,377 ) — (3,211 ) Net change in loans — intercompany 61 — (2 ) (59 ) — Purchases of operating lease assets — — (1,472 ) — (1,472 ) Disposals of operating lease assets 9 — 3,038 — 3,047 Acquisitions of subsidiaries, net of cash acquired (288 ) — — — (288 ) Capital contributions to subsidiaries (988 ) — — 988 — Returns of contributed capital 1,971 8 — (1,979 ) — Net change in restricted cash 1 — 481 — 482 Net change in nonmarketable equity investments — — (354 ) — (354 ) Other, net (82 ) — 13 — (69 ) Net cash (used in) provided by investing activities (150 ) 8 (67 ) (1,050 ) (1,259 ) Financing activities Net change in short-term borrowings — third party 123 — (2,235 ) — (2,112 ) Net (decrease) increase in deposits (29 ) — 6,337 — 6,308 Proceeds from issuance of long-term debt — third party 1,115 — 7,905 — 9,020 Repayments of long-term debt — third party (596 ) — (13,709 ) — (14,305 ) Net change in debt — intercompany (8 ) — (62 ) 70 — Redemption of preferred stock (696 ) — — — (696 ) Repurchase of common stock (14 ) — — — (14 ) Dividends paid — third party (30 ) — — — (30 ) Dividends paid and returns of contributed capital — intercompany — (8 ) (2,600 ) 2,608 — Capital contributions from parent — — 988 (988 ) — Net cash used in financing activities (135 ) (8 ) (3,376 ) 1,690 (1,829 ) Effect of exchange-rate changes on cash and cash equivalents — — 3 — 3 Net decrease in cash and cash equivalents (139 ) — (521 ) 11 (649 ) Cash and cash equivalents at beginning of year 1,635 — 5,595 (850 ) 6,380 Cash and cash equivalents at June 30, $ 1,496 $ — $ 5,074 $ (839 ) $ 5,731

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	Jun. 30, 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	6 Months Ended
	Jun. 30, 2017	Jun. 30, 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	$ 2,000,000	$ 5,000,000
Goodwill	240,000,000	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		$ 193,000,000
Automotive Finance Operations [Member]
Business Acquisition [Line Items]
Goodwill	$ 20,000,000	$ 20,000,000	$ 20,000,000	$ 20,000,000

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Discontinued Operations and Disposal Groups [Abstract]
Disposal Group, Including Discontinued Operation, Operating Income (Loss)	$ (2)	$ (2)	$ (1)	$ 2
Discontinued Operation, Tax Effect of Discontinued Operation	$ 0	$ (5)	$ 0	$ (4)

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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Other Nonoperating Income (Expense) [Abstract]
Remarketing Fees	$ 27	$ 25	$ 56	$ 53
Fees and Commissions, Other	25	22	52	47
Contractually Specified Servicing Fees, Late Fees, and Ancillary Fees Earned in Exchange for Servicing Financial Assets	14	18	30	31
Income (Loss) from Equity Method Investments	5	5	5	11
Other Income	32	26	75	49
Noninterest Income, Other Operating Income	$ 103	$ 96	$ 218	$ 191

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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 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			211	221
Prior Year Claims and Claims Adjustment Expense			2	(3)
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	$ 125	$ 145	213	218
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year			(183)	(184)
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years			(27)	(25)
Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid			(210)	(209)
Liability for Unpaid Claims and Claims Adjustment Expense, Net	44	58	44	58
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	135	106	135	106
Liability for Claims and Claims Adjustment Expense	$ 179	$ 164	$ 179	$ 164

Other Operating Expenses (Sched

Other Operating Expenses (Schedule Of Other Operating Expenses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Operating Expenses [Abstract]
Insurance Commissions	$ 104	$ 97	$ 203	$ 191
Communications and Information Technology	71	67	140	133
Lease And Loan Administration	39	34	75	66
Marketing and Advertising Expense	33	21	63	48
Regulatory and licensing fees	28	21	55	42
Vehicle remarketing and repossession	25	22	53	46
Professional Fees	27	26	53	50
Depreciation, Nonproduction	23	21	45	42
Occupancy, Net	11	12	23	25
Taxes, Miscellaneous	8	8	16	17
Other Cost and Expense, Operating	51	57	99	111
Other Noninterest Expense	$ 420	$ 386	$ 825	$ 771

Investment Securities (Investme

Investment Securities (Investment Table) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 21,997	$ 19,293
Available-for-sale Securities, Gross Unrealized Gains	90	68
Available-for-sale Securities, Gross Unrealized Losses	(323)	(435)
Available-for-sale securities	21,764	18,926
Held-to-maturity securities	1,189	839
Held-to-maturity Securities, Unrecognized Holding Gain	2	0
Held-to-maturity Securities, Unrecognized Holding Loss	(35)	(50)
Held-to-maturity Securities, Fair Value	1,156	789
Deposit Assets	12	14
Pledged Assets Separately Reported, Securities Pledged for Federal Home Loan Bank, at Fair Value	3,316	4,881
Financial Instruments Owned and Pledged as Collateral, Amount Eligible to be Repledged by Counterparty	1,420	737
Cash Equivalents, at Carrying Value	1,200	291
Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	21,448	18,651
Available-for-sale Debt Securities Gross Unrealized Gain	81	61
Available-for-sale Debt Securities, Gross Unrealized Loss	(270)	(381)
Available-for-sale Securities, Debt Securities	21,259	18,331
US Treasury and Government [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1,891	1,680
Available-for-sale Debt Securities Gross Unrealized Gain	0	0
Available-for-sale Debt Securities, Gross Unrealized Loss	(39)	(60)
Available-for-sale Securities, Debt Securities	1,852	1,620
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	780	794
Available-for-sale Debt Securities Gross Unrealized Gain	13	7
Available-for-sale Debt Securities, Gross Unrealized Loss	(11)	(19)
Available-for-sale Securities, Debt Securities	782	782
Foreign Government Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	148	157
Available-for-sale Debt Securities Gross Unrealized Gain	2	5
Available-for-sale Debt Securities, Gross Unrealized Loss	0	0
Available-for-sale Securities, Debt Securities	150	162
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	13,809	10,473
Available-for-sale Debt Securities Gross Unrealized Gain	39	29
Available-for-sale Debt Securities, Gross Unrealized Loss	(172)	(212)
Available-for-sale Securities, Debt Securities	13,676	10,290
Held-to-maturity securities	1,143	839
Held-to-maturity Securities, Unrecognized Holding Gain	2	0
Held-to-maturity Securities, Unrecognized Holding Loss	(35)	(50)
Held-to-maturity Securities, Fair Value	1,110	789
Residential Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	2,063	2,162
Available-for-sale Debt Securities Gross Unrealized Gain	11	5
Available-for-sale Debt Securities, Gross Unrealized Loss	(36)	(70)
Available-for-sale Securities, Debt Securities	2,038	2,097
Commercial Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	474	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	475	537
Asset-backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1,010	1,396
Available-for-sale Debt Securities Gross Unrealized Gain	6	6
Available-for-sale Debt Securities, Gross Unrealized Loss	(2)	(2)
Available-for-sale Securities, Debt Securities	1,014	1,400
Held-to-maturity securities	46	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	46	0
Corporate Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1,273	1,452
Available-for-sale Debt Securities Gross Unrealized Gain	8	7
Available-for-sale Debt Securities, Gross Unrealized Loss	(9)	(16)
Available-for-sale Securities, Debt Securities	1,272	1,443
Equity Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Equity Securities, Amortized Cost Basis	549	642
Available-for-sale Equity Securities, Gross Unrealized Gain	9	7
Available-for-sale Equity Securities, Gross Unrealized Loss	(53)	(54)
Available-for-sale Securities, Equity Securities	505	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	Jun. 30, 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	$ 21,259	$ 18,331
Available-for-sale debt securities, Yield	2.90%	2.80%
Available-for-sale debt securities, Due in one year or less, Amount	$ 163	$ 138
Available-for-sale debt securities, Due in one year or less, Yield	2.30%	2.00%
Available-for-sale debt securities, Due after one year through five years, Amount	$ 1,552	$ 2,046
Available-for-sale debt securities, Due after one year through five years, Yield	2.80%	2.70%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 2,637	$ 2,498
Available-for-sale debt securities, Due after five years through ten years, Yield	2.10%	2.20%
Available-for-sale debt securities, Due after ten years, Amount	$ 16,907	$ 13,649
Available-for-sale debt securities, Due after ten years, Yield	3.00%	2.90%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 21,448	$ 18,651
Amortized cost of available-for-sale debt securities, Due in one year or less, Amount	163	138
Amortized cost of available-for-sale debt securities, Due after one year through five years, Amount	1,545	2,040
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Amortized Cost Basis	2,675	2,563
Amortized cost of available-for-sale debt securities, Due after ten years, Amount	17,065	13,910
US Treasury and Government [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 1,852	$ 1,620
Available-for-sale debt securities, Yield	1.70%	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	$ 21	$ 60
Available-for-sale debt securities, Due after one year through five years, Yield	1.70%	1.60%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 1,831	$ 1,558
Available-for-sale debt securities, Due after five years through ten years, Yield	1.70%	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	$ 1,891	$ 1,680
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 782	$ 782
Available-for-sale debt securities, Yield	3.10%	3.10%
Available-for-sale debt securities, Due in one year or less, Amount	$ 38	$ 64
Available-for-sale debt securities, Due in one year or less, Yield	2.50%	1.70%
Available-for-sale debt securities, Due after one year through five years, Amount	$ 45	$ 29
Available-for-sale debt securities, Due after one year through five years, Yield	2.40%	2.30%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 165	$ 172
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	$ 534	$ 517
Available-for-sale debt securities, Due after ten years, Yield	3.30%	3.40%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 780	$ 794
Foreign Government Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 150	$ 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	$ 68	$ 58
Available-for-sale debt securities, Due after one year through five years, Yield	2.60%	2.80%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 82	$ 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	$ 148	$ 157
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 13,676	$ 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	$ 13,673	$ 10,261
Available-for-sale debt securities, Due after ten years, Yield	3.00%	2.90%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 13,809	$ 10,473
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	$ 1,143
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	$ 1,143
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	$ 2,038	$ 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	$ 2,038	$ 2,097
Available-for-sale debt securities, Due after ten years, Yield	2.90%	2.90%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 2,063	$ 2,162
Commercial Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 475	$ 537
Available-for-sale debt securities, Yield	3.10%	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	2.90%	2.80%
Available-for-sale debt securities, Due after ten years, Amount	$ 472	$ 534
Available-for-sale debt securities, Due after ten years, Yield	3.10%	2.60%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 474	$ 537
Asset-backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Debt Securities	$ 1,014	$ 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	$ 801	$ 1,059
Available-for-sale debt securities, Due after one year through five years, Yield	3.00%	2.80%
Available-for-sale debt securities, Due after five years through ten years, Amount	$ 57	$ 143
Available-for-sale debt securities, Due after five years through ten years, Yield	2.90%	3.20%
Available-for-sale debt securities, Due after ten years, Amount	$ 156	$ 198
Available-for-sale debt securities, Due after ten years, Yield	2.70%	2.60%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 1,010	$ 1,396
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	$ 46
Held-to-Maturity Debt Securities, Yield	1.60%
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount	$ 4
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	$ 41
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	$ 1
Held-to-Maturity Debt Securities, Due After Five Years Through Ten Years, Yield	3.00%
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	$ 1,272	$ 1,443
Available-for-sale debt securities, Yield	2.90%	2.80%
Available-for-sale debt securities, Due in one year or less, Amount	$ 125	$ 72
Available-for-sale debt securities, Due in one year or less, Yield	2.30%	2.20%
Available-for-sale debt securities, Due after one year through five years, Amount	$ 617	$ 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	$ 496	$ 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	$ 34	$ 42
Available-for-sale debt securities, Due after ten years, Yield	5.20%	4.70%
Available-for-sale Debt Securities, Amortized Cost Basis	$ 1,273	$ 1,452
Held-to-maturity Securities [Member]
Schedule of Investments [Line Items]
Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment	$ 1,189
Held-to-Maturity Debt Securities, Yield	2.90%
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount	$ 4
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	$ 41
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	$ 1
Held-to-Maturity Debt Securities, Due After Five Years Through Ten Years, Yield	3.00%
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount	$ 1,143
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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Taxable interest	$ 130	$ 89	$ 249	$ 183
Taxable dividends	3	5	5	9
Interest and dividends exempt from U.S. federal income tax	6	5	11	9
Interest and Dividend Income, Securities, Operating, Available-for-sale	146	$ 99	280	$ 201
Excludes Other Earning Assets [Member]
Interest and Dividend Income, Securities, Operating, Available-for-sale	$ 139		$ 265

Investment Securities (Schedule

Investment Securities (Schedule Of Realized Gain (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Available-for-sale Securities [Abstract]
Available-for-sale Securities, Gross Realized Gains	$ 24	$ 40	$ 51	$ 94
Available-for-sale Securities, Gross Realized Losses	(1)	(1)	(1)	(1)
Available-for-sale Securities, Gross Realized Gain (Loss)	$ 23	$ 39	$ 50	$ 93

Investment Securities (Schedu68

Investment Securities (Schedule of Unrealized Loss on Investments) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	$ 12,989	$ 12,356
Available-for-sale Securities, Unrealized Loss Less than 12 months	(235)	(317)
Available-for-sale Securities, Fair value 12 months or longer	1,542	2,038
Available-for-sale Securities, Unrealized Loss 12 months or longer	(88)	(118)
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	12,849	12,205
Available-for-sale Securities, Unrealized Loss Less than 12 months	(226)	(309)
Available-for-sale Securities, Fair value 12 months or longer	1,418	1,769
Available-for-sale Securities, Unrealized Loss 12 months or longer	(44)	(72)
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	1,829	1,612
Available-for-sale Securities, Unrealized Loss Less than 12 months	(39)	(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	401	524
Available-for-sale Securities, Unrealized Loss Less than 12 months	(10)	(19)
Available-for-sale Securities, Fair value 12 months or longer	15	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	26	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	9,293	8,052
Available-for-sale Securities, Unrealized Loss Less than 12 months	(162)	(196)
Available-for-sale Securities, Fair value 12 months or longer	448	587
Available-for-sale Securities, Unrealized Loss 12 months or longer	(10)	(16)
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	410	813
Available-for-sale Securities, Unrealized Loss Less than 12 months	(6)	(17)
Available-for-sale Securities, Fair value 12 months or longer	763	860
Available-for-sale Securities, Unrealized Loss 12 months or longer	(30)	(53)
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value Less than 12 months	102	47
Available-for-sale Securities, Unrealized Loss Less than 12 months	(1)	(1)
Available-for-sale Securities, Fair value 12 months or longer	49	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	293	375
Available-for-sale Securities, Unrealized Loss Less than 12 months	(1)	(2)
Available-for-sale Securities, Fair value 12 months or longer	107	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	495	744
Available-for-sale Securities, Unrealized Loss Less than 12 months	(7)	(14)
Available-for-sale Securities, Fair value 12 months or longer	36	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	140	151
Available-for-sale Securities, Unrealized Loss Less than 12 months	(9)	(8)
Available-for-sale Securities, Fair value 12 months or longer	124	269
Available-for-sale Securities, Unrealized Loss 12 months or longer	$ (44)	$ (46)

Finance Receivables and Loans69

Finance Receivables and Loans, Net (Schedule of Accounts, Notes, Loans and Financing Receivables) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 120,528	$ 118,944	$ 112,653
Derivative, Amount of Hedged Item	300	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	439	359
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	78,068	76,843
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	66,774	65,793	63,281
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	28	43
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	11,294	11,050	11,084
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	8,866	8,294
Held For Investment Mortgage Finance Receivables Interest Only Mortgage Loans	$ 24	30
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Six 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 Finance [Member] | One year and six 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 six months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	34.00%
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Three years and six months, or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	43.00%
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Four years and six 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 - Legacy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 2,428	2,756
Held For Investment Mortgage Finance Receivables Interest Only Mortgage Loans	$ 587	714
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Six months or less [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	7.00%
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | One year and six 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 six 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 six 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 six months, or greater [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest-only mortgage loan portfolio principal amortization	1.00%
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 42,460	42,101	$ 38,288
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	34,782	35,041
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	3,620	3,248
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 4,058	$ 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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Financing Receivable, Allowance for Loan and Lease Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	$ 1,155	$ 1,077	$ 1,144	$ 1,054
Allowance for Loan and Lease Losses, Write-offs	(296)	(237)	(646)	(500)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	97	85	194	169
Allowance for Loan and Lease Losses Write-offs, Net	(199)	(152)	(452)	(331)
Provision for Loan Losses Expensed	269	172	540	392
Allowance for Loan and Lease Losses, Adjustments, Other		8	7	26
Financing Receivable, Allowance for Credit Losses	1,225	1,089	1,225	1,089
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	97	86	97	86
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,128	1,003	1,128	1,003
Loans and Leases Receivable, Gross	120,528	112,653	120,528	112,653	$ 118,944
Financing Receivable, Individually Evaluated for Impairment	773	724	773	724
Financing Receivable, Collectively Evaluated for Impairment	119,755	111,929	119,755	111,929
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Allowance for Loan and Lease Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	941	850	932	834
Allowance for Loan and Lease Losses, Write-offs	(290)	(227)	(631)	(480)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	91	79	181	159
Allowance for Loan and Lease Losses Write-offs, Net	(199)	(148)	(450)	(321)
Provision for Loan Losses Expensed	260	168	527	375
Allowance for Loan and Lease Losses, Adjustments, Other		8	7	26
Financing Receivable, Allowance for Credit Losses	1,002	862	1,002	862
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	34	26	34	26
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	968	836	968	836
Loans and Leases Receivable, Gross	66,774	63,281	66,774	63,281	65,793
Financing Receivable, Individually Evaluated for Impairment	380	348	380	348
Financing Receivable, Collectively Evaluated for Impairment	66,394	62,933	66,394	62,933
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Allowance for Loan and Lease Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	86	115	91	114
Allowance for Loan and Lease Losses, Write-offs	(6)	(9)	(15)	(19)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	6	5	13	9
Allowance for Loan and Lease Losses Write-offs, Net	0	(4)	(2)	(10)
Provision for Loan Losses Expensed	(3)	(2)	(6)	5
Allowance for Loan and Lease Losses, Adjustments, Other		0	0	0
Financing Receivable, Allowance for Credit Losses	83	109	83	109
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	31	37	31	37
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	52	72	52	72
Loans and Leases Receivable, Gross	11,294	11,084	11,294	11,084	11,050
Financing Receivable, Individually Evaluated for Impairment	242	254	242	254
Financing Receivable, Collectively Evaluated for Impairment	11,052	10,830	11,052	10,830
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Allowance for Loan and Lease Losses [Roll Forward]
Financing Receivable, Allowance for Credit Losses	128	112	121	106
Allowance for Loan and Lease Losses, Write-offs	0	(1)	0	(1)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	0	1	0	1
Allowance for Loan and Lease Losses Write-offs, Net	0	0	0	0
Provision for Loan Losses Expensed	12	6	19	12
Allowance for Loan and Lease Losses, Adjustments, Other		0	0	0
Financing Receivable, Allowance for Credit Losses	140	118	140	118
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	32	23	32	23
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	108	95	108	95
Loans and Leases Receivable, Gross	42,460	38,288	42,460	38,288	$ 42,101
Financing Receivable, Individually Evaluated for Impairment	151	122	151	122
Financing Receivable, Collectively Evaluated for Impairment	$ 42,309	$ 38,166	$ 42,309	$ 38,166

Finance Receivables and Loans71

Finance Receivables and Loans, Net (Schedule of Sales of Financing Receivables and Loans) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Sales and Transfers	$ 88	$ 1,592	$ 1,304	$ 4,193
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Sales and Transfers	85	1,560	1,298	4,159
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Sales and Transfers	3	4	6	6
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Sales and Transfers	$ 0	$ 28	$ 0	$ 28

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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Purchases	$ 1,420	$ 1,018	$ 1,815	$ 2,388
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Purchases	611	0	679	0
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Significant Purchases	$ 809	$ 1,018	$ 1,136	$ 2,388

Finance Receivables and Loans73

Finance Receivables and Loans, Net (Past Due Financing Receivables and Loans) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 2,329	$ 2,759
Financing Receivable, Recorded Investment, Current	118,199	116,185
Loans and Leases Receivable, Gross	120,528	118,944	$ 112,653
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	2,303	2,749
Financing Receivable, Recorded Investment, Current	75,765	74,094
Loans and Leases Receivable, Gross	78,068	76,843
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	2,155	2,580
Financing Receivable, Recorded Investment, Current	64,619	63,213
Loans and Leases Receivable, Gross	66,774	65,793	63,281
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	148	169
Financing Receivable, Recorded Investment, Current	11,146	10,881
Loans and Leases Receivable, Gross	11,294	11,050	11,084
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	41	49
Financing Receivable, Recorded Investment, Current	8,825	8,245
Loans and Leases Receivable, Gross	8,866	8,294
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	107	120
Financing Receivable, Recorded Investment, Current	2,321	2,636
Loans and Leases Receivable, Gross	2,428	2,756
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	26	10
Financing Receivable, Recorded Investment, Current	42,434	42,091
Loans and Leases Receivable, Gross	42,460	42,101	$ 38,288
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	26	10
Financing Receivable, Recorded Investment, Current	34,756	35,031
Loans and Leases Receivable, Gross	34,782	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	3,620	3,248
Loans and Leases Receivable, Gross	3,620	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	4,058	3,812
Loans and Leases Receivable, Gross	4,058	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	1,653	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	1,635	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	1,569	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	66	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	32	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	34	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	18	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	18	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	371	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	371	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	350	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	21	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	3	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	18	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	305	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	297	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	236	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	61	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	6	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	55	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	8	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	8	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	Jun. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 783	$ 819
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	632	697
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	540	598
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	92	99
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	9	10
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	83	89
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	151	122
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	75	33
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	69	84
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 7	$ 5

Finance Receivables and Loans75

Finance Receivables and Loans, Net (Financing Receivable Credit Quality Indicators) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 120,528	$ 118,944	$ 112,653
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	78,068	76,843
Consumer Portfolio Segment [Member] | Consumer Loan [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	77,436	76,146
Consumer Portfolio Segment [Member] | Consumer Loan [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	632	697
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	66,774	65,793	63,281
Consumer Portfolio Segment [Member] | Automobile Loan [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	66,234	65,195
Consumer Portfolio Segment [Member] | Automobile Loan [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	540	598
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	11,294	11,050	$ 11,084
Consumer Portfolio Segment [Member] | Residential Mortgage [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	11,202	10,951
Consumer Portfolio Segment [Member] | Residential Mortgage [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	92	99
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	8,866	8,294
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	8,857	8,284
Consumer Portfolio Segment [Member] | Mortgage Finance [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	9	10
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,428	2,756
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Performing Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,345	2,667
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 83	$ 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	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 120,528	$ 118,944	$ 112,653
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	42,460	42,101	$ 38,288
Commercial Portfolio Segment [Member] | Commercial Loan [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	39,616	39,410
Commercial Portfolio Segment [Member] | Commercial Loan [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,844	2,691
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	34,782	35,041
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	32,851	33,160
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	1,931	1,881
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	3,620	3,248
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	2,859	2,597
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	761	651
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	4,058	3,812
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	3,906	3,653
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member] | Criticized [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 152	$ 159

Finance Receivables and Loans77

Finance Receivables and Loans, Net (Impaired Financing Receivables) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	$ 802	$ 795
Impaired Financing Receivable, Recorded Investment	773	739
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	201	199
Impaired Financing Receivable, with Related Allowance, Recorded Investment	572	540
Impaired Financing Receivable, Related Allowance	97	85
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	642	658
Impaired Financing Receivable, Recorded Investment	622	617
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	161	190
Impaired Financing Receivable, with Related Allowance, Recorded Investment	461	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	396	407
Impaired Financing Receivable, Recorded Investment	380	370
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	102	131
Impaired Financing Receivable, with Related Allowance, Recorded Investment	278	239
Impaired Financing Receivable, Related Allowance	34	28
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	246	251
Impaired Financing Receivable, Recorded Investment	242	247
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	59	59
Impaired Financing Receivable, with Related Allowance, Recorded Investment	183	188
Impaired Financing Receivable, Related Allowance	31	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	238	243
Impaired Financing Receivable, Recorded Investment	234	239
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	55	56
Impaired Financing Receivable, with Related Allowance, Recorded Investment	179	183
Impaired Financing Receivable, Related Allowance	31	34
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	160	137
Impaired Financing Receivable, Recorded Investment	151	122
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	40	9
Impaired Financing Receivable, with Related Allowance, Recorded Investment	111	113
Impaired Financing Receivable, Related Allowance	32	23
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	75	33
Impaired Financing Receivable, Recorded Investment	75	33
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	27	7
Impaired Financing Receivable, with Related Allowance, Recorded Investment	48	26
Impaired Financing Receivable, Related Allowance	5	3
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	78	99
Impaired Financing Receivable, Recorded Investment	69	84
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	10	0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	59	84
Impaired Financing Receivable, Related Allowance	26	19
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance	7	5
Impaired Financing Receivable, Recorded Investment	7	5
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3	2
Impaired Financing Receivable, with Related Allowance, Recorded Investment	4	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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 770	$ 706	$ 758	$ 691
Impaired Financing Receivable, Interest Income, Accrual Method	17	7	24	14
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	637	600	628	596
Impaired Financing Receivable, Interest Income, Accrual Method	8	7	15	13
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	391	341	381	335
Impaired Financing Receivable, Interest Income, Accrual Method	5	4	10	8
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	246	259	247	261
Impaired Financing Receivable, Interest Income, Accrual Method	3	3	5	5
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	8	8	8	8
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	0
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	238	251	239	253
Impaired Financing Receivable, Interest Income, Accrual Method	3	3	5	5
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	133	106	130	95
Impaired Financing Receivable, Interest Income, Accrual Method	9	0	9	1
Commercial Portfolio Segment [Member] | Commercial And Industrial Automobile [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	54	35	47	32
Impaired Financing Receivable, Interest Income, Accrual Method	1	0	1	0
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	73	65	77	56
Impaired Financing Receivable, Interest Income, Accrual Method	8	0	8	1
Commercial Portfolio Segment [Member] | Commercial Real Estate Automobile [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	6	6	6	7
Impaired Financing Receivable, Interest Income, Accrual Method	$ 0	$ 0	$ 0	$ 0

Finance Receivables and Loans79

Finance Receivables and Loans, Net (Troubled Debt Restructurings) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	$ 690		$ 690		$ 663
Financing Receivable, Modifications, Number of Contracts	5,782	4,795	12,284	10,449
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 127	$ 84	$ 277	$ 178
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 111	$ 73	$ 245	$ 154
Consumer Portfolio Segment [Member] | Consumer Loan [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	5,781	4,795	12,282	10,449
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 106	$ 84	$ 233	$ 178
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 90	$ 73	$ 201	$ 154
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	5,762	4,767	12,209	10,389
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 103	$ 79	$ 218	$ 168
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 88	$ 68	$ 187	$ 144
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	19	28	73	60
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 3	$ 5	$ 15	$ 10
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 2	$ 5	$ 14	$ 10
Consumer Portfolio Segment [Member] | Mortgage Finance [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	0	2	1	3
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 0	$ 1	$ 0	$ 2
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 1	$ 0	$ 2
Consumer Portfolio Segment [Member] | Mortgage - Legacy [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	19	26	72	57
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 3	$ 4	$ 15	$ 8
Financing Receivable, Modifications, Post-Modification Recorded Investment	2	$ 4	14	$ 8
Commercial Portfolio Segment [Member] | Commercial Loan [Member]
Financing Receivable, Modifications [Line Items]
Loans and Leases Receivable, Impaired, Commitment to Lend	$ 4		$ 4		$ 2
Financing Receivable, Modifications, Number of Contracts	1	0	2	0
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 21	$ 0	$ 44	$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 21	$ 0	$ 44	$ 0
Commercial Portfolio Segment [Member] | Commercial And Industrial Other [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts	1	0	2	0
Financing Receivable, Modifications, Pre-Modification Recorded Investment	$ 21	$ 0	$ 44	$ 0
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 21	$ 0	$ 44	$ 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		6 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	2,143	1,860	4,133	3,661
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 25	$ 23	$ 50	$ 46
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	$ 17	$ 13	$ 33	$ 25
Automobile Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	2,143	1,858	4,132	3,658
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 25	$ 23	$ 49	$ 46
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	$ 17	$ 13	$ 33	$ 25
Mortgage Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	0	1	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0	$ 1	$ 0
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	$ 0	$ 0	$ 0	$ 0
Mortgage - Legacy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts	0	2	0	3
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0	$ 0	$ 0
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	$ 0	$ 0	$ 0	$ 0

Investment in Operating Lease81

Investment in Operating Leases, Net (Investments In Operating Leases) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Leases, Operating [Abstract]
Property Subject to or Available for Operating Lease, Gross	$ 12,136	$ 14,584
Property Subject to or Available for Operating Lease, Accumulated Depreciation	(2,419)	(3,114)
Property Subject to or Available for Operating Lease, Net	$ 9,717	$ 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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Leases, Operating [Abstract]
Depreciation Expense On Operating Lease Assets	$ 353	$ 520	$ 739	$ 1,085
Gross Remarketing (Gains) Losses	(32)	(86)	(29)	(141)
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	$ 321	$ 434	$ 710	$ 944

Securitizations and Variable 83

Securitizations and Variable Interest Entities (Schedule of Variable Interest Entities) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Variable Interest Entity [Line Items]
Securitization or Asset-backed Financing Arrangement, Financial Asset for which Transfer is Accounted as Sale, Gain (Loss) on Sale	$ 0	$ 0	$ 2	$ 0
Assets of nonconsolidated variable interest entities	2,662		2,662		$ 2,899
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	3,429		3,429		3,574
Carrying value of assets for VIEs for which we have continuing involvement	33,134		33,134		37,631
Carrying value of liabilities for VIEs for which we have continuing involvement	12,827		12,827		13,490
Retained notes and certificated residual interest	48		48
Commercial Portfolio Segment [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	539		539		460
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	229		229		169
Assets of nonconsolidated variable interest entities	0		0		0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	719		719		651
Automobile Loan [Member] | Consumer Portfolio Segment [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	18,495		18,495		20,869
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	7,941		7,941		8,557
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	48		48		24
Variable Interest Entity, Nonconsolidated, Carrying Amount, Liabilities	0		0		0
Assets of nonconsolidated variable interest entities	2,662		2,662		2,899
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	2,710		2,710		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	46		46
Automobile Loan [Member] | Consumer Portfolio Segment [Member] | Other Assets [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	2		2
Automobile Loan [Member] | Commercial Portfolio Segment [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	14,052		14,052		16,278
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	4,657		4,657		4,764
Unencumbered [Member] | Automobile Loan [Member] | Consumer Portfolio Segment [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	9,000		9,000		9,600
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	$ 87		$ 87		$ 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	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash Flow Received and Paid to Nonconsolidated Securitization Entities [Line Items]
Cash Flows Between Transferor and Transferee, Proceeds from New Transfers	$ 1,187	$ 1,604
Cash Flows Between Transferor and Transferee, Purchases of Previously Transferred Financial Assets	(491)
Cash Flows Between Transferor and Transferee, Servicing Fees	18	17
Cash Flows Between Transferor and Transferee, Beneficial Interest	10
Cash Flows Between Transferor and Transferee, Receipts on Transferor's Interest in Transferred Financial Assets, Other	$ 4	$ 5

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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 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	$ 125,154		$ 125,154		$ 124,500
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	692		692		841
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	203	$ 155	460	$ 336
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	120,545		120,545		118,944
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	676		676		822
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	199	152	452	331
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	66,774		66,774		65,793
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	586		586		730
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	199	148	450	321
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	11,297		11,297		11,050
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	82		82		85
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	0	4	2	10
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	38,840		38,840		38,853
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	8		8		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	3,634		3,634		3,248
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	0		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	2,662		2,662		2,392
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	13		13		13
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	3	2	6	4
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	2,662		2,662		2,392
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	13		13		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	1,947		1,947		3,164
Delinquent Amount at End of Period on Loans Managed and Securitized or Asset-backed Financing Arrangement	3		3		$ 6
Net Credit Losses During Period on Loans Managed or Securitized or Asset-backed Financing Arrangement	$ 1	$ 1	$ 2	$ 1

Servicing Activities (Schedule

Servicing Activities (Schedule of Total Serviced Automobile Loans Outstanding) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 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	$ 14	$ 18	$ 30	$ 31
Total Primary Serviced Assets	119,667		119,667		$ 121,480
Consumer Loan [Member] | On-Balance Sheet Loans [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	66,491		66,491		65,646
Commercial Loan [Member] | On-Balance Sheet Loans [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	38,840		38,840		38,853
Operating Leases [Member] | On-Balance Sheet Loans [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	9,615		9,615		11,311
Other Assets [Member] | On-Balance Sheet Loans [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	67		67		67
Asset-backed Securities, Securitized Loans and Receivables [Member] | Off-Balance Sheet Loans [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	2,690		2,690		2,412
Whole-Loan Transactions [Member] | Off-Balance Sheet Loans [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	$ 1,964		$ 1,964		$ 3,191

Other Assets (Schedule of Other

Other Assets (Schedule of Other Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016	Aug. 01, 2016	Jun. 01, 2016
Goodwill [Line Items]
Goodwill	$ 240	$ 240
Property, Plant and Equipment, Gross	985	901
Accumulated depreciation	(565)	(525)
Property, Plant and Equipment, Net	420	376
Restricted cash collections for securitization trusts	1,259	1,694
Nonmarketable equity securities	938	1,046
Deferred Tax Assets, State Taxes	764	994
Interest Receivable	470	476
Goodwill	240	240
Cash reserve deposits held for securitization trusts	143	184
Accounts and Other Receivables, Net, Current	115	100
Restricted Cash and Cash Equivalents	113	111
Cash and securities collateral placed with counterparties	103	167
Derivative Asset, Fair Value, Gross Asset	41	95
Other Assets, Miscellaneous	1,347	1,371
Other Assets	5,953	6,854
Federal Home Loan Bank Stock	454	577
Federal Reserve Bank Stock	444	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	Jun. 30, 2017	Dec. 31, 2016
Deposits [Abstract]
Noninterest-bearing deposit liabilities	$ 107	$ 84
Interest-bearing Deposit Liabilities, by Component [Abstract]
Deposits, Savings Deposits	50,732	46,976
Time Deposits	35,299	31,795
Deposits, Retail	45	167
Deposits	86,183	79,022
Time Deposits, $100,000 or More	13,200	12,100
Time Deposits, at or Above FDIC Insurance Limit	$ 3,700	$ 3,500

Debt Debt (Schedule of Short-te

Debt Debt (Schedule of Short-term Debt) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Short-term Debt [Line Items]
Demand Notes	$ 3,457	$ 3,622
Federal Home Loan Bank, Advances, Maturities Summary, Due in Next Twelve Months	4,300	7,875
Securities Sold under Agreements to Repurchase, Gross	1,706	1,176
Other Short-term Borrowings	1,249	0
Short-term Debt	10,712	12,673
Non-derivative Cash Collateral Placed with Counterparties Associated with the Repurchase Agreements	11	45
Unsecured Debt [Member]
Short-term Debt [Line Items]
Demand Notes	3,457	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	4,706	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	4,300	7,875
Securities Sold under Agreements to Repurchase, Gross	1,706	1,176
Other Short-term Borrowings	0	0
Short-term Debt	6,006	9,051
Maturity Less than 30 Days [Member] | Secured Debt [Member]
Short-term Debt [Line Items]
U.S. Treasury Securities Sold under Agreements to Repurchase, Maturity Period	139
Mortgage-backed Residential Securities Sold under Agreements to Repurchase, Maturity Period	652
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	348
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	183
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	384	$ 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	Jun. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term Debt, Current Maturities	$ 11,744	$ 14,553
Long-term Debt, Excluding Current Maturities	37,101	39,260
Derivative, Amount of Hedged Item	300	315
Long-term debt	49,145	54,128
Secured Debt	37,591	43,129
Unsecured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Current Maturities	3,342	4,274
Long-term Debt, Excluding Current Maturities	13,909	15,450
Derivative, Amount of Hedged Item	309	326
Long-term debt	17,560	20,050
Secured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Current Maturities	8,402	10,279
Long-term Debt, Excluding Current Maturities	23,192	23,810
Derivative, Amount of Hedged Item	(9)	(11)
Long-term debt	31,585	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	$ 6,500	$ 6,100

Debt (Scheduled Remaining Matur

Debt (Scheduled Remaining Maturity of Long-term Debt) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	$ 6,569
Long-term Debt, Maturities, Repayments of Principal in Year Two	11,528
Long-term Debt, Maturities, Repayments of Principal in Year Three	10,252
Long-term Debt, Maturities, Repayments of Principal in Year Four	8,319
Long-term Debt, Maturities, Repayments of Principal in Year Five	3,161
Long-term Debt, Maturities, Repayments of Principal after Year Five	9,016
Derivative, Amount of Hedged Item	300	$ 315
Long-term debt	49,145	54,128
Unsecured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	1,745
Long-term Debt, Maturities, Repayments of Principal in Year Two	3,600
Long-term Debt, Maturities, Repayments of Principal in Year Three	1,642
Long-term Debt, Maturities, Repayments of Principal in Year Four	2,210
Long-term Debt, Maturities, Repayments of Principal in Year Five	595
Long-term Debt, Maturities, Repayments of Principal after Year Five	7,459
Derivative, Amount of Hedged Item	309	326
Long-term debt	17,560	20,050
Debt Instrument, Unamortized Discount	(47)
Debt Instrument, Unamortized Discount	(1,282)
Unsecured Debt [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount, Noncurrent	(100)
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	(43)
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	4,824
Long-term Debt, Maturities, Repayments of Principal in Year Two	7,928
Long-term Debt, Maturities, Repayments of Principal in Year Three	8,610
Long-term Debt, Maturities, Repayments of Principal in Year Four	6,109
Long-term Debt, Maturities, Repayments of Principal in Year Five	2,566
Long-term Debt, Maturities, Repayments of Principal after Year Five	1,557
Derivative, Amount of Hedged Item	(9)	(11)
Long-term debt	31,585	$ 34,078
Long-term Debt [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	1,792
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	2,249
Long-term Debt, Maturities, Repayments of Principal in Year Five	638
Long-term Debt, Maturities, Repayments of Principal after Year Five	8,473
Derivative, Amount of Hedged Item	309
Long-term debt	18,842
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	Jun. 30, 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	$ 3,260	$ 4,895
Pledged Assets, Mortgage assets held for investment	11,193	10,954
Pledged Assets, Investment in operating leases	956	2,040
Pledged Assets, Other, Not Separately Reported on Statement of Financial Position	58,950	65,222
Secured Debt	37,591	43,129
Short-term Debt	10,712	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	1,896	4,231
Pledged Assets, Mortgage assets held for investment	11,193	10,954
Pledged Assets, Investment in operating leases	28	913
Pledged Assets, Other, Not Separately Reported on Statement of Financial Position	35,271	41,129
Secured Debt	17,194	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	17,100	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	2,400	2,400
Secured Debt [Member]
Pledged Assets related to secured borrowings [Line Items]
Short-term Debt	6,006	9,051
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Pledged Assets related to secured borrowings [Line Items]
Pledged Assets, Not Separately Reported, Finance Receivables	25,658	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	4,421	5,751
Commercial Portfolio Segment [Member] | Automobile Loan [Member]
Pledged Assets related to secured borrowings [Line Items]
Pledged Assets, Not Separately Reported, Finance Receivables	17,883	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	$ 17,733	$ 19,280

Debt Debt (Narrative - Trust Pr

Debt Debt (Narrative - Trust Preferred Securities) (Details) $ / shares in Units, $ in Billions	Jun. 30, 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	Jun. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 16,425	$ 18,375
Long-term Line of Credit	13,880	14,800
Unused capacity	2,545	3,575
Bank Funding Member | Secured Debt [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	2,000	3,600
Long-term Line of Credit	1,750	3,250
Unused capacity	250	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	2,600
Nonbank Funding Member | Secured Debt [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	13,175	13,525
Long-term Line of Credit	10,880	11,550
Unused capacity	2,295	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	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Accounts Payable and Accrued Liabilities [Abstract]
Accounts Payable	$ 871	$ 649
Accrued Employee Benefits	182	232
Liability for Claims and Claims Adjustment Expense	179	149	$ 164	$ 169
Derivative Liability, Fair Value, Gross Liability	43	95
Deferred Revenue	40	56
Cash collateral received from counterparties	6	10
Other Accrued Liabilities	571	546
Accounts Payable and Accrued Liabilities	$ 1,892	$ 1,737

Accumulated Other Comprehensi96

Accumulated Other Comprehensive (Loss) Income (Rollforward) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 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	$ 75	$ 120	96	262
Ending Balance Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	(177)	103	(177)	103
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	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			1	0
Ending Balance Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	9	8	9	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)	(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	76	120	96	266
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (245)	$ 35	$ (245)	$ 35

Accumulated Other Comprehensi97

Accumulated Other Comprehensive (Loss) Income (Before and After Tax) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 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	$ 132	$ 185	$ 183	$ 465
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax	23	39	50	93
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent	109	146	133	372
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax [Abstract]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	(37)	(25)	(42)	(129)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax	(3)	1	(5)	(19)
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax, Portion Attributable to Parent	(34)	(26)	(37)	(110)
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	95	160	141	336
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax	20	40	45	74
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	75	120	96	262
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	4	(1)	6	12
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax		(1)		(1)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent		0		13
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax [Abstract]
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	(1)	0	(2)	(5)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Tax		0		0
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax, Portion Attributable to Parent		0		(5)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax [Abstract]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	3	(1)	4	7
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax		(1)		(1)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent		0		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	(4)		(6)	(6)
Other Comprehensive Income Unrealized Gain Loss On Cash Flow Hedges Arising During the Period, Before Tax	1		1
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		2	3
Other Comprehensive Income Unrealized Gain Loss On Cash Flow Hedges Arising During the Period, Tax	0		0
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	(3)		(4)	(3)
Other Comprehensive Income Unrealized Gain Loss On Net Cash Flow Hedges Arising During the Period Net of Tax	1		1
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	110	146	133	378
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(34)	(26)	(37)	(112)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ 76	$ 120	$ 96	$ 266

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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	$ 254	$ 357	$ 467	$ 604
Dividends, Preferred Stock, Cash	0	(15)	0	(30)
Net income (loss) from continuing operations attributable to common shareholders	254	342	467	574
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	(2)	3	(1)	6
Net Income (Loss) Available to Common Stockholders, Basic	$ 252	$ 345	$ 466	$ 580
Weighted Average Number of Shares Outstanding, Basic	457,891	485,370	461,904	484,802
Weighted Average Number of Shares Outstanding, Diluted	458,819	486,074	462,802	485,364
Earnings Per Share, Basic [Abstract]
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.55	$ 0.70	$ 1.01	$ 1.18
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	(0.01)	0.01	0	0.01
Earnings Per Share, Basic	0.55	0.71	1.01	1.20
Earnings Per Share, Diluted [Abstract]
Income (Loss) from Continuing Operations, Per Diluted Share	0.55	0.70	1.01	1.18
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	(0.01)	0.01	0	0.01
Earnings Per Share, Diluted	$ 0.55	$ 0.71	$ 1.01	$ 1.19

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	6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jul. 18, 2017	Jun. 28, 2017	Jan. 11, 2017	Dec. 31, 2016	Oct. 18, 2016	Sep. 30, 2016	Jul. 18, 2016	Jun. 29, 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	$ 444		$ 444				$ 435
assets greater than $50 billion	50,000		50,000
FRB Approved Capital Action - Dividends					$ 0.12						$ 0.08
Stock Repurchase Program, Authorized Amount	$ 700		$ 700
Dividends Payable, Amount Per Share	$ 0.08		$ 0.08			$ 0.08		$ 0.08	$ 0.08	$ 0.08
Treasury Stock, Value, Acquired, Cost Method	$ 373	$ 14	$ 699
Treasury Stock, Common, Shares	35,625,615		35,625,615
Common Stock, Shares, Outstanding	452,291,918	483,753,360	452,291,918				467,000,306
Increase (decrease) in shares of common stock outstanding		6.50%
Increase (Decrease) in Dividends Payable	50.00%		50.00%
Increase (decrease) in share repurchase program	9.00%		9.00%
Subsequent Event [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Dividends Payable, Amount Per Share				$ 0.12
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	$ 13,066		$ 13,066				$ 12,978
Percentage of Common Equity Tier 1 Capital to Risk-weighted Assets	9.47%		9.47%				9.37%
Tier One Risk Based Capital	$ 15,417		$ 15,417				$ 15,147
Tier One Risk Based Capital to Risk Weighted Assets	11.18%		11.18%				10.93%
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.00%		6.00%
Capital	$ 17,704		$ 17,704				$ 17,419
Capital to Risk Weighted Assets	12.83%		12.83%				12.57%
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%		10.00%
Tier One Leverage Capital	$ 15,417		$ 15,417				$ 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	$ 18,975		$ 18,975				$ 17,888
Percentage of Common Equity Tier 1 Capital to Risk-weighted Assets	17.89%		17.89%				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	$ 18,975		$ 18,975				$ 17,888
Tier One Risk Based Capital to Risk Weighted Assets	17.89%		17.89%				16.70%
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%		8.00%
Capital	$ 19,651		$ 19,651				$ 18,458
Capital to Risk Weighted Assets	18.53%		18.53%				17.24%
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%		10.00%
Tier One Leverage Capital	$ 18,975		$ 18,975				$ 17,888
Tier One Leverage Capital to Average Assets	15.31%		15.31%				15.21%
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%		5.00%
2017 through 2018 [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Stock Repurchase Program, Authorized Amount	$ 760		$ 760

Derivative Instruments and H100

Derivative Instruments and Hedging Activities (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Cash Collateral Placed with Counterparties Excluding Cash Collateral Associated with Repurchase Agreements	$ 92	$ 122
Securities Collateral Placed with Counterparties	56	72
Non-derivative Cash Collateral Placed with Counterparties Associated with the Repurchase Agreements	11	45
Cash Collateral Received from Counterparties, Excluding Collateral Associated with Repurchase Agreements	6	10
Non-cash collateral received	$ 3	$ 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	Jun. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 41	$ 95
Derivative Liability, Fair Value, Gross Liability	43	95
Derivative, Notional Amount	29,434	34,166
Interest Receivable	470	476
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	20
Derivative Liability, Fair Value, Gross Liability	3	21
Derivative, Notional Amount	4,379	4,902
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	19
Derivative Liability, Fair Value, Gross Liability	0	21
Derivative, Notional Amount	4,225	4,731
Hedge notional amount associated with debt maturing in five or more years	3,300
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	3	0
Derivative, Notional Amount	154	171
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	40	73
Derivative Liability, Fair Value, Gross Liability	39	73
Derivative, Notional Amount	24,913	29,172
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	1
Derivative Liability, Fair Value, Gross Liability	1	0
Derivative, Notional Amount	142	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	0	8
Receive-fixed Swaps, Fair Value, Gross Liability	0	14
Receive-fixed Swaps, Notional Amount	3,300	1,700
Pay-fixed Swaps, Fair Value, Gross Asset	0	10
Pay-fixed Swaps, Fair Value, Gross Liability	0	1
Pay-fixed Swaps, Notional Amount	0	2,800
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Pay-fixed Swaps, Fair Value, Gross Asset	0
Pay-fixed Swaps, Notional Amount	650
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	15	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	1	1
Derivative Liability, Fair Value, Gross Liability	1	0
Derivative, Notional Amount	142	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	103	0
Written Options [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	0
Derivative Liability, Fair Value, Gross Liability	39	73
Derivative, Notional Amount	12,449	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	39	73
Derivative Liability, Fair Value, Gross Liability	0	0
Derivative, Notional Amount	12,346	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	41	75
Derivative Liability, Fair Value, Gross Liability	40	74
Derivative, Notional Amount	25,055	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	240	240
Derivative assets in net asset position [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	39	87
Interest Receivable	0	7
Derivative assets in net liability positions [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ 0	$ 0	$ (1)	$ (5)
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(3)	0	(7)	(9)
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	0	1	(2)	3
Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	(3)	0	(4)	(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)	0	(2)
Interest Income [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(1)	(6)	1	(34)
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	1	0	1	0
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	0	5	1	12
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	6	4	11	9
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	21	40	39
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	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	1	5	(3)	33
Interest Expense [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	20	51	24	242
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	7	11	12	27
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	2	0	3
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	(20)	(50)	(23)	(246)
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)	0	(2)
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	(1)	1	(3)	3
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	(3)	1	(4)	(3)
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	4	1	5	3
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)	$ 0	$ (2)

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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Cumulative Translation Adjustment, Net of Tax, Period Increase (Decrease)	$ 4	$ 0	$ 7	$ 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	$ 4	$ 0	$ 6	$ 6

Income Taxes Income Taxes (Inco

Income Taxes Income Taxes (Income Tax Expense) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Income Tax Expense (Benefit)	$ 122	$ 56	$ 235	$ 206
Other Tax Expense (Benefit)		$ 175

Fair Value (Fair Value Measurme

Fair Value (Fair Value Measurment - Recurring Basis) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 21,764	$ 18,926
Derivative Assets	40	74
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	$ (39)	$ (70)
Available-for-sale, Equity Investment in Any One Industry Did Not Exceed Percentage	18.00%	14.00%
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 21,764	$ 18,926
Mortgages Held-for-sale, Fair Value Disclosure	3
Retained Interest, Fair Value Disclosure	5	29
Derivative Assets	41	95
Assets, Fair Value Disclosure	21,813	19,050
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(43)	(95)
Liabilities, Fair Value Disclosure	(43)	(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	(39)	(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	(4)
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	21,259	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	1,852	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	782	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	150	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	13,676	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	2,038	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	475	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	1,014	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	1,272	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	505	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	40	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	1	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	2,364	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	2,364	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	1,859	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	1,852	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	7	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	505	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	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	19,400	16,700
Mortgages Held-for-sale, Fair Value Disclosure	0
Retained Interest, Fair Value Disclosure	0	0
Derivative Assets	40	94
Assets, Fair Value Disclosure	19,440	16,794
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(43)	(94)
Liabilities, Fair Value Disclosure	(43)	(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	(39)	(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	(4)
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	19,400	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	782	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	143	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	13,676	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	2,038	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	475	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	1,014	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	1,272	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	39	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	1	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	3
Retained Interest, Fair Value Disclosure	5	29
Derivative Assets	1	0
Assets, Fair Value Disclosure	9	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	1	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	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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Beginning balance	$ 32	$ 31	$ 29	$ 40
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	2	1	2	3
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	20	0	23	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	(14)	2	(12)	6
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances	0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(31)	(3)	(33)	(18)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Assets, Ending balance	9	31	9	31
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	1	0	1	0
Loans Held-for-Sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Beginning balance	1		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	20		23
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	(18)		(20)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Assets, Ending balance	3		3
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0		0
Retained Interest [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Beginning balance	31	31	29	40
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	1	1	1	3
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	4	2	8	6
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances	0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(31)	(3)	(33)	(18)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Assets, Ending balance	5	31	5	31
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	$ 0	0	$ 0
Derivative [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value, Beginning balance	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	1		1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Issuances	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Assets, Ending balance	1		1
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 1		$ 1

Fair Value (Fair Value Measu107

Fair Value (Fair Value Measurement - Nonrecurring Basis) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 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	$ 17	$ 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	13		$ 15
Lower of cost or fair value or valuation reserve allowance	0		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	45		43
Lower of cost or fair value or valuation reserve allowance	(6)		(6)
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	34		46
Lower of cost or fair value or valuation reserve allowance	(25)		(18)
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	79		89
Lower of cost or fair value or valuation reserve allowance	(31)		(24)
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	13		10
Lower of cost or fair value or valuation reserve allowance	(1)		(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		5
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		119
Lower of cost or fair value or valuation reserve allowance	(32)		(27)
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		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		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	13		15
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	45		43
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	34		46
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	79		89
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	13		10
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		5
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		$ 119

Fair Value (Fair Value of Finan

Fair Value (Fair Value of Financial Instruments) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	$ 1,189	$ 839
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	17	0
Loans and Leases Receivable, Net Amount	119,303	117,800
Nonmarketable equity securities	938	1,046
Deposits	86,183	79,022
Short-term Debt	10,712	12,673
Long-term Debt	49,145	54,128
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	1,189	839
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	17
Loans and Leases Receivable, Net Amount	119,303	117,800
Nonmarketable equity securities	925	1,046
Deposits	86,183	79,022
Short-term Debt	10,712	12,673
Long-term Debt	49,145	54,128
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	1,156	789
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	17
Loans and Leases Receivable, Net Amount	121,029	118,750
Nonmarketable equity securities	923	1,067
Deposits	84,287	78,469
Short-term Debt	10,714	12,675
Long-term Debt	51,534	56,120
Estimate of 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 Receivable Held-for-sale, Net, Not Part of Disposal Group	0
Loans and Leases Receivable, Net Amount	0	0
Nonmarketable equity securities	0	0
Deposits	0	0
Short-term Debt	0	0
Long-term Debt	0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	1,156	789
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	0
Loans and Leases Receivable, Net Amount	0	0
Nonmarketable equity securities	898	1,012
Deposits	0	0
Short-term Debt	0	0
Long-term Debt	32,371	22,036
Estimate of 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 Receivable Held-for-sale, Net, Not Part of Disposal Group	17
Loans and Leases Receivable, Net Amount	121,029	118,750
Nonmarketable equity securities	25	55
Deposits	84,287	78,469
Short-term Debt	10,714	12,675
Long-term Debt	19,163	$ 34,084
Equity Securities [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nonmarketable equity securities	13
Equity Securities [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Nonmarketable equity securities	$ 34

Offsetting Assets and Liabil109

Offsetting Assets and Liabilities Offsetting Assets and Liabilities (Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 41	$ 95
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	41	95
Derivative Asset, Not Subject to Master Netting Arrangement	(1)	(12)
Derivative, Collateral, Obligation to Return Cash	0	(9)
Derivative Asset	40	74
Customer Securities for which Entity has Right to Sell or Repledge, Fair Value	3	6
Derivative assets in net asset position [Member]
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset	39	87
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	39	87
Derivative Asset, Not Subject to Master Netting Arrangement	0	(4)
Derivative, Collateral, Obligation to Return Cash	0	(9)
Derivative Asset	39	74
Derivative assets in net liability positions [Member]
Offsetting Assets [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	8
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	1	8
Derivative Asset, Not Subject to Master Netting Arrangement	(1)	(8)
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset	$ 0	$ 0

Offsetting Assets and Liabil110

Offsetting Assets and Liabilities Offsetting Assets and Liabilities (Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Offsetting Liabilities [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 41	$ 95
Derivative Liability, Fair Value, Gross Liability	(43)	(95)
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	41	95
Derivative Asset, Not Subject to Master Netting Arrangement	(1)	(12)
Derivative, Collateral, Obligation to Return Cash	0	(9)
Derivative Asset	40	74
Derivative Liability, Fair Value, Amount Offset Against Collateral	(43)	(95)
Derivative Liability, Not Subject to Master Netting Arrangement Deduction	0	12
Derivative, Collateral, Right to Reclaim Cash	4	13
Derivative Liability	(39)	(70)
Customer Securities for which Entity has Right to Sell or Repledge, Fair Value	3	6
Derivative assets in net liability positions [Member]
Offsetting Liabilities [Line Items]
Derivative Asset, Fair Value, Gross Asset	1	8
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	1	8
Derivative Asset, Not Subject to Master Netting Arrangement	(1)	(8)
Derivative, Collateral, Obligation to Return Cash	0	0
Derivative Asset	0	0
Derivative assets with no offsetting arrangements [Member] [Domain]
Offsetting Liabilities [Line Items]
Derivative Asset, Fair Value, Gross Asset	1
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	1
Derivative Asset, Not Subject to Master Netting Arrangement	0
Derivative, Collateral, Obligation to Return Cash	0
Derivative Asset	1
Derivative Liabilities in Net Liability Positions [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	(43)	(91)
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(43)	(91)
Derivative Liability, Not Subject to Master Netting Arrangement Deduction	0	8
Derivative, Collateral, Right to Reclaim Cash	4	13
Derivative Liability	(39)	(70)
Derivative liabilities in net asset positions [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	0	(4)
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	0	(4)
Derivative Liability, Not Subject to Master Netting Arrangement Deduction	0	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	(1,322)	(676)
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(1,322)	(676)
Derivative Liability, Not Subject to Master Netting Arrangement Deduction	0	0
Derivative, Collateral, Right to Reclaim Cash	1,322	676
Derivative Liability	0	0
Total Derivative Liabilities [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	(1,365)	(771)
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(1,365)	(771)
Derivative Liability, Not Subject to Master Netting Arrangement Deduction	0	12
Derivative, Collateral, Right to Reclaim Cash	1,326	689
Derivative Liability	$ (39)	$ (70)

Segment Information (Financial

Segment Information (Financial Information Operating Segments) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net Financing Revenue	$ 1,067	$ 984	$ 2,046	$ 1,935
Nonoperating Income (Expense)	388	374	784	750
Revenues	1,455	1,358	2,830	2,685
Provision for Loan Losses Expensed	269	172	540	392
Noninterest Expense	810	773	1,588	1,483
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	376	413	702	810
Assets	164,345	157,931	164,345	157,931	$ 163,728
Net Interest Income (Loss) after Provision for Loan Losses	798	812	1,506	1,543
Automotive Finance Operations [Member]
Segment Reporting Information [Line Items]
Net Financing Revenue	932	929	1,824	1,825
Nonoperating Income (Expense)	107	77	208	154
Revenues	1,039	1,006	2,032	1,979
Provision for Loan Losses Expensed	266	170	534	379
Noninterest Expense	426	410	863	837
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	347	426	635	763
Assets	115,447	112,356	115,447	112,356
Insurance Operations Member
Segment Reporting Information [Line Items]
Net Financing Revenue	14	16	29	30
Nonoperating Income (Expense)	245	259	509	513
Revenues	259	275	538	543
Provision for Loan Losses Expensed	0	0	0	0
Noninterest Expense	280	293	519	511
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(21)	(18)	19	32
Assets	7,308	7,193	7,308	7,193
Mortgage Finance Operations [Member]
Segment Reporting Information [Line Items]
Net Financing Revenue	32	26	66	46
Nonoperating Income (Expense)	1	0	1	0
Revenues	33	26	67	46
Provision for Loan Losses Expensed	1	0	2	3
Noninterest Expense	25	17	49	32
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	7	9	16	11
Assets	8,902	8,014	8,902	8,014
Corporate Finance Operations [Member]
Segment Reporting Information [Line Items]
Net Financing Revenue	48	29	82	57
Nonoperating Income (Expense)	10	4	28	10
Revenues	58	33	110	67
Provision for Loan Losses Expensed	6	3	12	9
Noninterest Expense	17	16	38	33
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	35	14	60	25
Assets	3,552	2,989	3,552	2,989
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Net Financing Revenue	41	(16)	45	(23)
Nonoperating Income (Expense)	25	34	38	73
Revenues	66	18	83	50
Provision for Loan Losses Expensed	(4)	(1)	(8)	1
Noninterest Expense	62	37	119	70
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	8	(18)	(28)	(21)
Assets	$ 29,136	$ 27,379	$ 29,136	$ 27,379

Parent and Guarantor Condens112

Parent and Guarantor Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statement of Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	$ 1,447	$ 1,265	$ 2,815	$ 2,500
Interest and Dividend Income, Securities, Operating	146	99	280	201
Interest Income, Deposits with Financial Institutions	7	4	12	7
Operating Leases, Income Statement, Lease Revenue	488	701	1,031	1,470
Total financing revenue and other interest income	2,088	2,069	4,138	4,178
Interest Expense, Deposits	250	203	481	396
Interest Expense, Short-term Borrowings	33	12	60	25
Interest Expense, Long-term Debt	417	436	841	878
Interest Expense, Related Party	0	0	0	0
Interest Expense	700	651	1,382	1,299
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	321	434	710	944
Net Financing Revenue	1,067	984	2,046	1,935
Dividends From Non Bank Subsidiary	0	0	0	0
Insurance Services Revenue	227	236	468	466
Gain (Loss) on Sales of Loans, Net	36	3	50	4
Gain (Loss) on Extinguishment of Debt	(1)	0	(2)	(4)
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	23	39	50	93
Noninterest Income, Other Operating Income	103	96	218	191
Nonoperating Income (Expense)	388	374	784	750
Revenues	1,455	1,358	2,830	2,685
Provision for Loan Losses Expensed	269	172	540	392
Labor and Related Expense	265	242	550	494
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	125	145	213	218
Other Noninterest Expense	420	386	825	771
Noninterest Expense	810	773	1,588	1,483
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	376	413	702	810
Income Tax Expense (Benefit)	122	56	235	206
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	254	357	467	604
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	(2)	3	(1)	6
Undistributed income of bank subsidiaries	0	0	0	0
Undistributed income of nonbank subsidiaries	0	0	0	0
Net Income (Loss) Attributable to Parent	252	360	466	610
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	76	120	96	266
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	328	480	562	876
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	(35)	(28)	(70)	(66)
Interest and Dividend Income, Securities, Operating	0	0	0	0
Interest Income, Deposits with Financial Institutions	2	1	4	2
Operating Leases, Income Statement, Lease Revenue	3	5	6	10
Total financing revenue and other interest income	(27)	(19)	(53)	(48)
Interest Expense, Deposits	1	2	2	4
Interest Expense, Short-term Borrowings	19	10	36	20
Interest Expense, Long-term Debt	274	290	556	578
Interest Expense, Related Party	4	4	8	9
Interest Expense	298	306	602	611
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	3	3	5	7
Net Financing Revenue	(328)	(328)	(660)	(666)
Dividends From Non Bank Subsidiary	387	148	427	629
Insurance Services Revenue	0	0	0	0
Gain (Loss) on Sales of Loans, Net	32	(2)	30	(5)
Gain (Loss) on Extinguishment of Debt	0		0	(2)
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	0	0	0	0
Noninterest Income, Other Operating Income	163	317	431	690
Nonoperating Income (Expense)	195	315	461	683
Revenues	254	135	228	646
Provision for Loan Losses Expensed	82	88	189	148
Labor and Related Expense	19	139	140	286
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	0	0	0	0
Other Noninterest Expense	213	317	501	656
Noninterest Expense	232	456	641	942
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(60)	(409)	(602)	(444)
Income Tax Expense (Benefit)	(93)	(65)	(227)	(108)
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	33	(344)	(375)	(336)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	3	2	9
Undistributed income of bank subsidiaries	375	336	764	607
Undistributed income of nonbank subsidiaries	(156)	365	75	330
Net Income (Loss) Attributable to Parent	252	360	466	610
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	76	120	96	266
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	328	480	562	876
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	0	0	0	0
Interest and Dividend Income, Securities, Operating	0	0	0	0
Interest Income, Deposits with Financial Institutions	0	0	0	0
Operating Leases, Income Statement, Lease Revenue	0	0	0	0
Total financing revenue and other interest income	0	0	0	0
Interest Expense, Deposits	0	0	0	0
Interest Expense, Short-term Borrowings	0	0	0	0
Interest Expense, Long-term Debt	0	0	0	0
Interest Expense, Related Party	0	0	0	0
Interest Expense	0	0	0	0
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	0	0	0	0
Net Financing Revenue	0	0	0	0
Dividends From Non Bank Subsidiary	0	0	0	0
Insurance Services Revenue	0	0	0	0
Gain (Loss) on Sales of Loans, Net	0	0	0	0
Gain (Loss) on Extinguishment of Debt	0		0	0
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	0	0	0	0
Noninterest Income, Other Operating Income	0	0	0	0
Nonoperating Income (Expense)	0	0	0	0
Revenues	0	0	0	0
Provision for Loan Losses Expensed	0	0	0	0
Labor and Related Expense	0	0	0	0
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	0	0	0	0
Other Noninterest Expense	0	0	0	0
Noninterest Expense	0	0	0	0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	0	0	0	0
Income Tax Expense (Benefit)	0	(82)	0	(82)
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	0	82	0	82
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	0	0	0
Undistributed income of bank subsidiaries	375	336	764	607
Undistributed income of nonbank subsidiaries	0	(2)	0	(2)
Net Income (Loss) Attributable to Parent	375	416	764	687
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	50	62	55	145
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	425	478	819	832
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	1,482	1,293	2,885	2,566
Interest and Dividend Income, Securities, Operating	146	99	281	201
Interest Income, Deposits with Financial Institutions	5	3	8	5
Operating Leases, Income Statement, Lease Revenue	485	696	1,025	1,460
Total financing revenue and other interest income	2,122	2,095	4,206	4,241
Interest Expense, Deposits	249	201	479	392
Interest Expense, Short-term Borrowings	14	2	24	5
Interest Expense, Long-term Debt	143	146	285	300
Interest Expense, Related Party	3	3	7	6
Interest Expense	409	352	795	703
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	318	431	705	937
Net Financing Revenue	1,395	1,312	2,706	2,601
Dividends From Non Bank Subsidiary	0	0	0	0
Insurance Services Revenue	227	236	468	466
Gain (Loss) on Sales of Loans, Net	4	5	20	9
Gain (Loss) on Extinguishment of Debt	(1)		(2)	(2)
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	23	39	50	93
Noninterest Income, Other Operating Income	211	214	435	430
Nonoperating Income (Expense)	464	494	971	996
Revenues	1,859	1,806	3,677	3,597
Provision for Loan Losses Expensed	187	84	351	244
Labor and Related Expense	246	103	410	208
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	125	145	213	218
Other Noninterest Expense	478	502	972	1,044
Noninterest Expense	849	750	1,595	1,470
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	823	972	1,731	1,883
Income Tax Expense (Benefit)	215	203	462	396
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	608	769	1,269	1,487
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	(2)	0	(3)	(3)
Undistributed income of bank subsidiaries	0	0	0	0
Undistributed income of nonbank subsidiaries	0	0	0	0
Net Income (Loss) Attributable to Parent	606	769	1,266	1,484
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	72	91	91	243
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	678	860	1,357	1,727
Affiliated Entity [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	0	0	0	0
Interest Income, Deposits with Financial Institutions	0	0	0	0
Affiliated Entity [Member] | Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	3	3	7	6
Interest Income, Deposits with Financial Institutions	0	0	0	0
Affiliated Entity [Member] | Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	0	0	0	0
Interest Income, Deposits with Financial Institutions	0	0	0	0
Affiliated Entity [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	2	2	4	4
Interest Income, Deposits with Financial Institutions	2	2	3	5
Consolidation, Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	0	0	0	0
Interest and Dividend Income, Securities, Operating	0	0	(1)	0
Interest Income, Deposits with Financial Institutions	0	0	0	0
Operating Leases, Income Statement, Lease Revenue	0	0	0	0
Total financing revenue and other interest income	(7)	(7)	(15)	(15)
Interest Expense, Deposits	0	0	0	0
Interest Expense, Short-term Borrowings	0	0	0	0
Interest Expense, Long-term Debt	0	0	0	0
Interest Expense, Related Party	(7)	(7)	(15)	(15)
Interest Expense	(7)	(7)	(15)	(15)
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	0	0	0	0
Net Financing Revenue	0	0	0	0
Dividends From Non Bank Subsidiary	(387)	(148)	(427)	(629)
Insurance Services Revenue	0	0	0	0
Gain (Loss) on Sales of Loans, Net	0	0	0	0
Gain (Loss) on Extinguishment of Debt	0		0	0
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments	0	0	0	0
Noninterest Income, Other Operating Income	(271)	(435)	(648)	(929)
Nonoperating Income (Expense)	(271)	(435)	(648)	(929)
Revenues	(658)	(583)	(1,075)	(1,558)
Provision for Loan Losses Expensed	0	0	0	0
Labor and Related Expense	0	0	0	0
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	0	0	0	0
Other Noninterest Expense	(271)	(433)	(648)	(929)
Noninterest Expense	(271)	(433)	(648)	(929)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(387)	(150)	(427)	(629)
Income Tax Expense (Benefit)	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(387)	(150)	(427)	(629)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	0	0	0
Undistributed income of bank subsidiaries	(750)	(672)	(1,528)	(1,214)
Undistributed income of nonbank subsidiaries	156	(363)	(75)	(328)
Net Income (Loss) Attributable to Parent	(981)	(1,185)	(2,030)	(2,171)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(122)	(153)	(146)	(388)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	(1,103)	(1,338)	(2,176)	(2,559)
Consolidation, Eliminations [Member] | Affiliated Entity [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	(5)	(5)	(11)	(10)
Interest Income, Deposits with Financial Institutions	$ (2)	$ (2)	$ (3)	$ (5)

Parent and Guarantor Condens113

Parent and Guarantor Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Balance Sheet) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and Due from Banks	$ 1,514		$ 1,547
Interest-bearing Deposits in Banks and Other Financial Institutions	2,863		4,387
Cash and Cash Equivalents, at Carrying Value	4,377		5,934	$ 5,731		$ 6,380
Trading Securities			0
Available-for-sale securities	21,764		18,926
Held-to-maturity securities	1,189		839
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	17		0
Loans and Leases Receivable, Gross	120,528		118,944	112,653
Loans to bank subsidiary	0		0
Loans to nonbank subsidiary	0		0
Financing Receivable, Allowance for Credit Losses	1,225	$ 1,155	1,144	1,089	$ 1,077	1,054
Loans and Leases Receivable, Net Amount	119,303		117,800
Property Subject to or Available for Operating Lease, Net	9,717		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	2,025		1,905
Other Assets	5,953		6,854
Assets	164,345		163,728	157,931
Noninterest-bearing deposit liabilities	107		84
Interest-bearing Deposit Liabilities	86,076		78,938
Deposits	86,183		79,022
Short-term Debt	10,712		12,673
Long-term Debt	49,145		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	399		351
Unearned Premiums	2,541		2,500
Accounts Payable and Accrued Liabilities	1,892		1,737
Liabilities	150,872		150,411
Stockholders' Equity Attributable to Parent	13,473		13,317	13,611		13,439
Liabilities and Equity	164,345		163,728
Parent Company [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and Due from Banks	591		720
Interest-bearing Deposits in Banks and Other Financial Institutions	850		100
Cash and Cash Equivalents, at Carrying Value	1,441		820	1,496		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	5,733		4,705
Loans to bank subsidiary	250		1,125
Loans to nonbank subsidiary	833		1,779
Financing Receivable, Allowance for Credit Losses	144		115
Loans and Leases Receivable, Net Amount	6,672		7,494
Property Subject to or Available for Operating Lease, Net	29		42
Receivables from bank subsidiary	85		299
Receivables from nonbank subsidiary	50		107
Investment in bank subsidiaries	18,869		17,727
Investment in nonbank subsidiaries	10,023		10,318
Premiums receivable and other insurance assets	0		0
Other Assets	3,482		4,347
Assets	40,657		41,154
Noninterest-bearing deposit liabilities	0		0
Interest-bearing Deposit Liabilities	45		167
Deposits	45		167
Short-term Debt	4,706		3,622
Long-term Debt	20,755		21,798
Debt Payable To Bank Subsidiaries	95		330
Debt Payable To Nonbank Subsidiaries	937		1,027
Payables to Bank Subsidiaries	1
Payables to Nonbank Subsidiaries	199		153
Interest payable	192		253
Unearned Premiums	0		0
Accounts Payable and Accrued Liabilities	254		487
Liabilities	27,184		27,837
Stockholders' Equity Attributable to Parent	13,473		13,317
Liabilities and Equity	40,657		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
Financing Receivable, Allowance for Credit Losses	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	18,869		17,727
Investment in nonbank subsidiaries	0		0
Premiums receivable and other insurance assets	0		0
Other Assets	0		0
Assets	18,869		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	18,869		17,727
Liabilities and Equity	18,869		17,727
Non-Guarantor Subsidiaries [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and Due from Banks	923		827
Interest-bearing Deposits in Banks and Other Financial Institutions	2,013		4,287
Cash and Cash Equivalents, at Carrying Value	3,493		5,515	5,074		5,595
Trading Securities			82
Available-for-sale securities	21,764		19,253
Held-to-maturity securities	1,284		839
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	17
Loans and Leases Receivable, Gross	114,795		114,239
Loans to bank subsidiary	0		0
Loans to nonbank subsidiary	380		626
Financing Receivable, Allowance for Credit Losses	1,081		1,029
Loans and Leases Receivable, Net Amount	114,094		113,836
Property Subject to or Available for Operating Lease, Net	9,688		11,428
Receivables from bank subsidiary	0		0
Receivables from nonbank subsidiary	145		67
Investment in bank subsidiaries	0		0
Investment in nonbank subsidiaries	0		0
Premiums receivable and other insurance assets	2,055		1,936
Other Assets	4,684		5,085
Assets	157,224		158,041
Noninterest-bearing deposit liabilities	107		84
Interest-bearing Deposit Liabilities	86,031		78,771
Deposits	86,138		78,855
Short-term Debt	6,006		9,051
Long-term Debt	28,390		32,330
Debt Payable To Bank Subsidiaries	0		0
Debt Payable To Nonbank Subsidiaries	1,089		2,903
Payables to Bank Subsidiaries	0
Payables to Nonbank Subsidiaries	110		351
Interest payable	207		98
Unearned Premiums	2,541		2,500
Accounts Payable and Accrued Liabilities	3,852		3,911
Liabilities	128,333		129,999
Stockholders' Equity Attributable to Parent	28,891		28,042
Liabilities and Equity	157,224		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	557		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	(557)		(401)	$ (839)		$ (850)
Trading Securities			(82)
Available-for-sale securities	(6)		(327)
Held-to-maturity securities	(95)		0
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	0
Loans and Leases Receivable, Gross	0		0
Loans to bank subsidiary	(250)		(1,125)
Loans to nonbank subsidiary	(1,213)		(2,405)
Financing Receivable, Allowance for Credit Losses	0		0
Loans and Leases Receivable, Net Amount	(1,463)		(3,530)
Property Subject to or Available for Operating Lease, Net	0		0
Receivables from bank subsidiary	(85)		(299)
Receivables from nonbank subsidiary	(195)		(174)
Investment in bank subsidiaries	(37,738)		(35,454)
Investment in nonbank subsidiaries	(10,023)		(10,318)
Premiums receivable and other insurance assets	(30)		(31)
Other Assets	(2,213)		(2,578)
Assets	(52,405)		(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	(95)		(330)
Debt Payable To Nonbank Subsidiaries	(2,026)		(3,930)
Payables to Bank Subsidiaries	(1)
Payables to Nonbank Subsidiaries	(309)		(504)
Interest payable	0		0
Unearned Premiums	0		0
Accounts Payable and Accrued Liabilities	(2,214)		(2,661)
Liabilities	(4,645)		(7,425)
Stockholders' Equity Attributable to Parent	(47,760)		(45,769)
Liabilities and Equity	(52,405)		(53,194)
Consolidation, Eliminations [Member] | Affiliated Entity [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Interest-bearing Deposits in Banks and Other Financial Institutions	$ (557)		$ (401)

Parent and Guarantor Condens114

Parent and Guarantor Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statement of Cash Flows) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities	$ 2,070	$ 2,436
Payments to Acquire Available-for-sale Securities	(5,853)	(8,657)
Proceeds from sales of available-for-sale securities	2,162	6,584
Proceeds from maturities and repayment of available-for-sale securities	1,230	1,536
Payments to Acquire Held-to-maturity Securities	(313)	(571)
Proceeds from Sale and Maturity of Held-to-maturity Securities	17	0
Payments to Acquire Loans Held-for-investment	1,817	2,442
Proceeds from Sale of Loans and Leases Held-for-investment	1,280	4,156
Originations and repayments of loans held-for-investment and other	(1,588)	(3,211)
Purchases of operating lease assets	(1,965)	(1,472)
Disposals of operating lease assets	3,043	3,047
Payments to Acquire Interest in Subsidiaries and Affiliates	0	288
Proceeds from Contributions from Parent	0	0
Returns of contributed capital	0	0
Increase (Decrease) in Restricted Cash	474	482
Increase (Decrease) in Non marketable equity securities	107	(354)
Payments for (Proceeds from) Other Investing Activities	(93)	(69)
Net cash provided by investing activities	(3,316)	(1,259)
Proceeds from (Repayments of) Short-term Debt	(1,962)	(2,112)
Increase (Decrease) in Deposits	7,133	6,308
Proceeds from issuance of long-term debt	9,330	9,020
Repayments of long-term debt	(14,366)	(14,305)
Net Change in Debt, Intercompany	0	0
Payments for Repurchase of Redeemable Preferred Stock		696
Payments for Repurchase of Common Stock	(373)	(14)
Payments of Dividends	(75)	(30)
Dividends paid and returns of contributed capital, Intercompany	0	0
Capital contributions from parent	0	0
Net cash (used in) provided by financing activities	(313)	(1,829)
Effect of exchange-rate changes on cash and cash equivalents	2	3
Cash and Cash Equivalents, Period Increase (Decrease)	(1,557)	(649)
Cash and Cash Equivalents, at Carrying Value	5,934	6,380
Cash and Cash Equivalents, at Carrying Value	4,377	5,731
Parent Company [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities	561	146
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	35	0
Proceeds from Sale of Loans and Leases Held-for-investment	67	0
Originations and repayments of loans held-for-investment and other	1,044	(834)
Purchases of operating lease assets	0	0
Disposals of operating lease assets	4	9
Payments to Acquire Interest in Subsidiaries and Affiliates		288
Proceeds from Contributions from Parent	(824)	(988)
Returns of contributed capital	838	1,971
Increase (Decrease) in Restricted Cash	(45)	1
Increase (Decrease) in Non marketable equity securities	0	0
Payments for (Proceeds from) Other Investing Activities	(26)	(82)
Net cash provided by investing activities	2,888	(150)
Proceeds from (Repayments of) Short-term Debt	1,083	123
Increase (Decrease) in Deposits	(123)	(29)
Proceeds from issuance of long-term debt	353	1,115
Repayments of long-term debt	(3,323)	(596)
Net Change in Debt, Intercompany	(370)	(8)
Payments for Repurchase of Redeemable Preferred Stock		696
Payments for Repurchase of Common Stock	(373)	(14)
Payments of Dividends	(75)	(30)
Dividends paid and returns of contributed capital, Intercompany	0	0
Capital contributions from parent	0	0
Net cash (used in) provided by financing activities	(2,828)	(135)
Effect of exchange-rate changes on cash and cash equivalents	0	0
Cash and Cash Equivalents, Period Increase (Decrease)	621	(139)
Cash and Cash Equivalents, at Carrying Value	820	1,635
Cash and Cash Equivalents, at Carrying Value	1,441	1,496
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 and Leases Held-for-investment	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
Payments to Acquire Interest in Subsidiaries and Affiliates		0
Proceeds from Contributions from Parent	0	0
Returns of contributed capital	0	8
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	8
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 Redeemable Preferred Stock		0
Payments for Repurchase of Common Stock	0	0
Payments of Dividends	0	0
Dividends paid and returns of contributed capital, Intercompany	0	(8)
Capital contributions from parent	0	0
Net cash (used in) provided by financing activities	0	(8)
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	1,856	2,919
Payments to Acquire Available-for-sale Securities	(5,853)	(8,657)
Proceeds from sales of available-for-sale securities	2,162	6,584
Proceeds from maturities and repayment of available-for-sale securities	1,230	1,536
Payments to Acquire Held-to-maturity Securities	(313)	(571)
Proceeds from Sale and Maturity of Held-to-maturity Securities	17
Payments to Acquire Loans Held-for-investment	1,782	2,442
Proceeds from Sale of Loans and Leases Held-for-investment	1,213	4,156
Originations and repayments of loans held-for-investment and other	(676)	(2,377)
Purchases of operating lease assets	(1,965)	(1,472)
Disposals of operating lease assets	3,039	3,038
Payments to Acquire Interest in Subsidiaries and Affiliates		0
Proceeds from Contributions from Parent	0	0
Returns of contributed capital	0	0
Increase (Decrease) in Restricted Cash	524	481
Increase (Decrease) in Non marketable equity securities	107	(354)
Payments for (Proceeds from) Other Investing Activities	24	13
Net cash provided by investing activities	(1,758)	(67)
Proceeds from (Repayments of) Short-term Debt	(3,045)	(2,235)
Increase (Decrease) in Deposits	7,256	6,337
Proceeds from issuance of long-term debt	7,016	7,905
Repayments of long-term debt	(11,043)	(13,709)
Net Change in Debt, Intercompany	(1,864)	(62)
Payments for Repurchase of Redeemable Preferred Stock		0
Payments for Repurchase of Common Stock	0	0
Payments of Dividends	0	0
Dividends paid and returns of contributed capital, Intercompany	(1,266)	(2,600)
Capital contributions from parent	824	988
Net cash (used in) provided by financing activities	(2,122)	(3,376)
Effect of exchange-rate changes on cash and cash equivalents	2	3
Cash and Cash Equivalents, Period Increase (Decrease)	(2,022)	(521)
Cash and Cash Equivalents, at Carrying Value	5,515	5,595
Cash and Cash Equivalents, at Carrying Value	3,493	5,074
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	1,864	61
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	(269)
Payments for (Proceeds from) Loans and Leases	246	(2)
Consolidation, Eliminations [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net Cash Provided by (Used in) Operating Activities	(347)	(629)
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 and Leases Held-for-investment	0	0
Originations and repayments of loans held-for-investment and other	(1,956)	0
Purchases of operating lease assets	0	0
Disposals of operating lease assets	0	0
Payments to Acquire Interest in Subsidiaries and Affiliates		0
Proceeds from Contributions from Parent	824	988
Returns of contributed capital	(838)	(1,979)
Increase (Decrease) in Restricted Cash	(5)	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	(4,446)	(1,050)
Proceeds from (Repayments of) Short-term Debt	0	0
Increase (Decrease) in Deposits	0	0
Proceeds from issuance of long-term debt	1,961	0
Repayments of long-term debt	0	0
Net Change in Debt, Intercompany	2,234	70
Payments for Repurchase of Redeemable Preferred Stock		0
Payments for Repurchase of Common Stock	0	0
Payments of Dividends	0	0
Dividends paid and returns of contributed capital, Intercompany	1,266	2,608
Capital contributions from parent	(824)	(988)
Net cash (used in) provided by financing activities	4,637	1,690
Effect of exchange-rate changes on cash and cash equivalents	0	0
Cash and Cash Equivalents, Period Increase (Decrease)	(156)	11
Cash and Cash Equivalents, at Carrying Value	(401)	(850)
Cash and Cash Equivalents, at Carrying Value	(557)	(839)
Consolidation, Eliminations [Member] | Affiliated Entity [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Payments for (Proceeds from) Investments	270
Payments for (Proceeds from) Loans and Leases	$ (2,110)	$ (59)

Contingencies and Other Risks (

Contingencies and Other Risks (Details) $ in Millions	54 Months Ended
	Jun. 30, 2017USD ($)
Loss Contingency [Abstract]
Consent Order Fees and Expenses	$ 240

Subsequent Events (Details)

Subsequent Events (Details) - $ / shares	Jul. 18, 2017	Jun. 30, 2017	Jan. 11, 2017	Oct. 18, 2016	Sep. 30, 2016	Jul. 18, 2016
Subsequent Event [Line Items]
Dividends Payable, Amount Per Share		$ 0.08	$ 0.08	$ 0.08	$ 0.08	$ 0.08
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends Payable, Amount Per Share	$ 0.12