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)