Parent and Guarantor Consolidating Financial Statements (Schedule of Condensed Consolidating Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and Due from Banks	$ 1,547	$ 2,148
Interest-bearing Deposits in Banks and Other Financial Institutions	4,387	4,232
Cash and Cash Equivalents, at Carrying Value	5,934	6,380	$ 5,576	$ 5,531
Trading Securities	0
Available-for-sale securities	18,926	17,157
Held-to-maturity securities	839	0
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group	0	105
Loans and Leases Receivable, Gross	118,944	111,600
Loans to bank subsidiary	0	0
Loans to nonbank subsidiary	0	0
Loans and Leases Receivable, Allowance	(1,144)	(1,054)	(977)
Loans and Leases Receivable, Net Amount	117,800	110,546
Property Subject to or Available for Operating Lease, Net	11,470	16,271
Receivables from bank subsidiary	0	0
Receivables from nonbank subsidiary	0	0
Investment in bank subsidiaries	0	0
Investment in nonbank subsidiaries	0	0
Premiums receivable and other insurance assets	1,905	1,801
Other Assets	6,854	6,321
Assets	163,728	158,581	151,631
Noninterest-bearing deposit liabilities	84	89
Interest-bearing Deposit Liabilities	78,938	66,389
Deposits	79,022	66,478
Short-term Debt	12,673	8,101
Long-term Debt	54,128	66,234
Debt Payable To Bank Subsidiaries	0
Debt Payable To Nonbank Subsidiaries	0	0
Payables to Bank Subsidiaries		0
Payables to Nonbank Subsidiaries	0	0
Interest payable	351	350
Unearned Premiums	2,500	2,434
Accounts Payable and Accrued Liabilities	1,737	1,545
Liabilities	150,411	145,142
Stockholders' Equity Attributable to Parent	13,317	13,439	15,399	14,208
Liabilities and Equity	163,728	158,581
Parent Company [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and Due from Banks	720	1,234
Interest-bearing Deposits in Banks and Other Financial Institutions	100	401
Cash and Cash Equivalents, at Carrying Value	820	1,635	2,286	2,930
Trading Securities	0
Available-for-sale securities	0	0
Held-to-maturity securities	0
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group		0
Loans and Leases Receivable, Gross	4,705	2,636
Loans to bank subsidiary	1,125	600
Loans to nonbank subsidiary	1,779	3,277
Loans and Leases Receivable, Allowance	(115)	(72)
Loans and Leases Receivable, Net Amount	7,494	6,441
Property Subject to or Available for Operating Lease, Net	42	81
Receivables from bank subsidiary	299	186
Receivables from nonbank subsidiary	107	259
Investment in bank subsidiaries	17,727	16,496
Investment in nonbank subsidiaries	10,318	10,902
Premiums receivable and other insurance assets	0	0
Other Assets	4,347	4,785
Assets	41,154	40,785
Noninterest-bearing deposit liabilities	0	0
Interest-bearing Deposit Liabilities	167	229
Deposits	167	229
Short-term Debt	3,622	3,453
Long-term Debt	21,798	21,048
Debt Payable To Bank Subsidiaries	330
Debt Payable To Nonbank Subsidiaries	1,027	1,409
Payables to Bank Subsidiaries		142
Payables to Nonbank Subsidiaries	153	420
Interest payable	253	258
Unearned Premiums	0	0
Accounts Payable and Accrued Liabilities	487	387
Liabilities	27,837	27,346
Stockholders' Equity Attributable to Parent	13,317	13,439
Liabilities and Equity	41,154	40,785
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	37
Trading Securities	0
Available-for-sale securities	0	0
Held-to-maturity securities	0
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group		0
Loans and Leases Receivable, Gross	0	0
Loans to bank subsidiary	0	0
Loans to nonbank subsidiary	0	0
Loans and Leases Receivable, Allowance	0	0
Loans and Leases Receivable, Net Amount	0	0
Property Subject to or Available for Operating Lease, Net	0	0
Receivables from bank subsidiary	0	0
Receivables from nonbank subsidiary	0	0
Investment in bank subsidiaries	17,727	16,496
Investment in nonbank subsidiaries	0	11
Premiums receivable and other insurance assets	0	0
Other Assets	0	0
Assets	17,727	16,507
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
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	82
Liabilities	0	82
Stockholders' Equity Attributable to Parent	17,727	16,425
Liabilities and Equity	17,727	16,507
Non-Guarantor Subsidiaries [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and Due from Banks	827	914
Interest-bearing Deposits in Banks and Other Financial Institutions	4,287	3,831
Cash and Cash Equivalents, at Carrying Value	5,515	5,595	3,905	2,974
Trading Securities	82
Available-for-sale securities	19,253	17,157
Held-to-maturity securities	839
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group		105
Loans and Leases Receivable, Gross	114,239	108,964
Loans to bank subsidiary	0	0
Loans to nonbank subsidiary	626	559
Loans and Leases Receivable, Allowance	(1,029)	(982)
Loans and Leases Receivable, Net Amount	113,836	108,541
Property Subject to or Available for Operating Lease, Net	11,428	16,190
Receivables from bank subsidiary	0	0
Receivables from nonbank subsidiary	67	282
Investment in bank subsidiaries	0	0
Investment in nonbank subsidiaries	0	0
Premiums receivable and other insurance assets	1,936	1,827
Other Assets	5,085	4,488
Assets	158,041	154,185
Noninterest-bearing deposit liabilities	84	89
Interest-bearing Deposit Liabilities	78,771	66,160
Deposits	78,855	66,249
Short-term Debt	9,051	4,648
Long-term Debt	32,330	45,186
Debt Payable To Bank Subsidiaries	0
Debt Payable To Nonbank Subsidiaries	2,903	3,877
Payables to Bank Subsidiaries		0
Payables to Nonbank Subsidiaries	351	191
Interest payable	98	92
Unearned Premiums	2,500	2,434
Accounts Payable and Accrued Liabilities	3,911	4,028
Liabilities	129,999	126,705
Stockholders' Equity Attributable to Parent	28,042	27,480
Liabilities and Equity	158,041	154,185
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	401	850
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	(401)	(850)	$ (615)	$ (410)
Trading Securities	(82)
Available-for-sale securities	(327)	0
Held-to-maturity securities	0
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group		0
Loans and Leases Receivable, Gross	0	0
Loans to bank subsidiary	(1,125)	(600)
Loans to nonbank subsidiary	(2,405)	(3,836)
Loans and Leases Receivable, Allowance	0	0
Loans and Leases Receivable, Net Amount	(3,530)	(4,436)
Property Subject to or Available for Operating Lease, Net	0	0
Receivables from bank subsidiary	(299)	(186)
Receivables from nonbank subsidiary	(174)	(541)
Investment in bank subsidiaries	(35,454)	(32,992)
Investment in nonbank subsidiaries	(10,318)	(10,913)
Premiums receivable and other insurance assets	(31)	(26)
Other Assets	(2,578)	(2,952)
Assets	(53,194)	(52,896)
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	(330)
Debt Payable To Nonbank Subsidiaries	(3,930)	(5,286)
Payables to Bank Subsidiaries		(142)
Payables to Nonbank Subsidiaries	(504)	(611)
Interest payable	0	0
Unearned Premiums	0	0
Accounts Payable and Accrued Liabilities	(2,661)	(2,952)
Liabilities	(7,425)	(8,991)
Stockholders' Equity Attributable to Parent	(45,769)	(43,905)
Liabilities and Equity	(53,194)	(52,896)
Consolidation, Eliminations [Member] | Affiliated Entity [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Interest-bearing Deposits in Banks and Other Financial Institutions	$ (401)	$ (850)