Condensed Consolidated Statement of Comprehensive Income Condensed Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Financing Revenue and Other Income [Line Items]
Interest and Fee Income, Loans and Leases	$ 1,543	$ 1,368
Interest and Dividend Income, Securities, Operating, Available-for-sale	176	134
Interest Income, Deposits with Financial Institutions	15	5
Operating Leases, Income Statement, Lease Revenue	382	543
Total financing revenue and other interest income	2,116	2,050
Interest Expense [Abstract]
Interest Expense, Deposits	351	231
Interest Expense, Short-term Borrowings	32	27
Interest Expense, Long-term Debt	411	424
Interest Expense	794	682
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	273	389
Net Financing Revenue	1,049	979
Other revenue [Abstract]
Insurance Services Revenue	256	241
Gain (Loss) on Sales of Loans, Net	1	14
Gain (Loss) on Investments	(12)	27
Noninterest Income, Other Operating Income	109	114
Nonoperating Income (Expense)	354	396
Revenues	1,403	1,375
Provision for Loan Losses Expensed	261	271
Noninterest Expense [Abstract]
Labor and Related Expense	306	285
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	63	88
Other Noninterest Expense	445	405
Noninterest Expense	814	778
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	328	326
Income Tax Expense (Benefit)	76	113
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	252	213
Net Income (Loss) Attributable to Parent	250	214
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(328)	20
Other Comprehensive Income (Loss), Net of Tax	(328)	20
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	(78)	234
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	$ (2)	$ 1
Earnings Per Share, Basic [Abstract]
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.58	$ 0.46
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	(0.01)	0.00
Earnings Per Share, Basic	0.57	0.46
Earnings Per Share, Diluted [Abstract]
Income (Loss) from Continuing Operations, Per Diluted Share	0.57	0.46
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	(0.01)	0.00
Earnings Per Share, Diluted	0.57	0.46
Common Stock, Dividends, Per Share, Declared	$ 0.13	$ 0.08
Retained Earnings [Member]
Net Income (Loss) Attributable to Parent	$ 250	$ 214