Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Statement of Cash Flows [Abstract]
Interest Paid	$ 349	$ 408		$ 396
Cash Flows from Operating Activities:
Net income including noncontrolling interests	528	797		629
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
(Reversal of) provision for credit losses	228	6		(29)
Depreciation, amortization and accretion, net	378	324		434
Stock-based compensation—restricted stock units	54	34		21
Deferred income taxes	(61)	99		76
Net gains on sales of securities	(20)	(18)		(178)
Net decrease (increase) in trading account assets	27	(263)		357
Net decrease (increase) in other assets	104	(59)		(305)
Net increase (decrease) in trading account liabilities	(98)	354		(355)
Net increase (decrease) in other liabilities	134	409		361
Loans originated for sale	(1,294)	(841)		(622)
Net proceeds from sale of loans originated for sale	1,157	839		599
Pension and other benefits adjustment	(106)	(80)		(262)
Other, net	(24)	21		(37)
Total adjustments	479	825		60
Net cash provided by (used in) operating activities	1,007	1,622		689
Cash Flows from Investing Activities:
Proceeds from sales of securities available for sale	1,985	1,376		8,340
Proceeds from paydowns and maturities of securities available for sale	2,022	2,373		3,451
Purchases of securities available for sale	(4,768)	(1,317)		(11,106)
Proceeds from paydowns and maturities of securities held to maturity	2,682	1,047		501
Purchases of securities held to maturity	(4,511)	(2,845)		(1,682)
Proceeds from sales of loans	1,207	196		254
Net decrease (increase) in loans	(2,039)	(8,664)		(4,912)
Purchases of other investments	(615)	(545)		(159)
Net cash acquired from (paid for) acquisitions	0	0		(3,185)
Other, net	(131)	(141)		(33)
Net cash provided by (used in) investing activities	(4,168)	(8,520)		(8,531)
Cash Flows from Financing Activities:
Net increase (decrease) in deposits	(1,710)	5,903		5,224
Proceeds from (Repayments of) Short-term Debt	(1,666)	141		1,200
Common equity contribution from BTMU	0	0		1,200
Proceeds from issuance of long-term debt	6,197	749		3,049
Repayment of long-term debt	(817)	(318)		(2,103)
Other, net	(61)	(25)		(25)
Change in noncontrolling interests	(4)	(4)		9
Net cash provided by (used in) financing activities	1,939	6,446		8,554
Net change in cash and cash equivalents	(1,222)	(452)		712
Cash and cash equivalents at beginning of period	5,751	6,203		5,491
Cash and cash equivalents at end of period	4,529	5,751		6,203
Cash Paid During the Period For:
Income taxes, net	84	38		15
Acquisitions:
Fair value of assets acquired	0	0		3,487
Fair value of liabilities assumed	0	0		573
Transfer of assets and liabilities from BTMU:
Carrying amount of assets acquired	0	70	[1]	0
Carrying amount of liabilities assumed	0	31	[1]	0
Supplemental Schedule of Noncash Investing and Financing Activities:
Transfer to Investments	0	0		4,386
Net transfer of loans held for investment to loans held for sale	1,207	196		246
Transfer of loans held for investment to OREO	$ 24	$ 28		$ 49

[1] For additional information on the transfer of assets and liabilities from BTMU, refer to Note 20 to these consolidated financial statements.