Balance Sheets - Parent Company Only (Details) - USD ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets [Abstract]
Cash and Due from Banks		$ 5,349	$ 5,091
Interest-bearing Deposits in Banks and Other Financial Institutions		25	25
Cash and cash equivalents		6,912	6,423	$ 5,599	$ 8,229
Available-for-sale Securities	[1]	31,416	30,672
Goodwill		6,331	6,337
Other Assets		8,949	6,405
Total assets		205,962	204,875
Liabilities and Shareholders' Equity
Long-term Debt	[2],[3]	9,785	11,748
Other Liabilities		4,179	2,996
Total liabilities		180,808	181,257
Preferred Stock, Value, Outstanding		2,475	1,225	1,225
Common Stock, Value, Outstanding		550	550
Additional Paid in Capital		9,000	9,010
Retained Earnings (Accumulated Deficit)		17,540	16,000
Treasury Stock, Value	[4]	(3,591)	(2,346)
Accumulated Other Comprehensive Income (Loss), Net of Tax		(820)	(821)	(460)	(122)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		25,154	23,618	23,437	23,005
Liabilities and Equity		205,962	204,875
Parent Company [Member]
Assets [Abstract]
Cash and Due from Banks		701	535
Cash, Cash Equivalents, and Short-term Investments		2,144	1,126
Interest-bearing Deposits in Banks and Other Financial Institutions		24	23
Cash and cash equivalents		2,869	1,684	$ 2,615	$ 2,623
Available-for-sale Securities		123	147
Due from Affiliates		1,218	2,516
Equity Method Investments		24,590	23,617
Investments in and Advances to Affiliates, Amount of Equity		1,423	1,359
Goodwill		211	211
Other Assets		547	528
Total assets		30,981	30,062
Liabilities and Shareholders' Equity
Due to Affiliate, Current		205	283
Short-term Bank Loans and Notes Payable		350	483
Long-term Debt		4,466	4,950
Other Liabilities		909	831
Total liabilities		5,930	6,547
Preferred Stock, Value, Outstanding		2,475	1,225
Common Stock, Value, Outstanding		550	550
Additional Paid in Capital		9,000	9,010
Retained Earnings (Accumulated Deficit)		17,540	16,000
Treasury Stock, Value		(3,694)	(2,449)
Accumulated Other Comprehensive Income (Loss), Net of Tax		(820)	(821)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		25,051	23,515
Liabilities and Equity		$ 30,981	$ 30,062

[1] Includes securities AFS pledged as collateral where counterparties have the right to sell or repledge the collateral of $223 million and $0 million at December 31, 2017 and December 31, 2016, respectively.

[2] Includes $530 million and $963 million of long-term debt measured at fair value at December 31, 2017 and 2016, respectively.

[3] Includes debt of consolidated VIEs of $189 million and $222 million at December 31, 2017 and December 31, 2016, respectively.

[4] At December 31, 2017, includes ($3,694) million for treasury stock and $103 million for noncontrolling interest.At December 31, 2016, includes ($2,448) million for treasury stock, ($1) million for the compensation element of restricted stock, and $103 million for noncontrolling interest.At December 31, 2015, includes ($1,764) million for treasury stock,($2) million for the compensation element of restricted stock, and $108 million for noncontrolling interest.