Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Cash Flows [Abstract]
Interest Paid	$ 106	$ 76
Cash Flows from Operating Activities:
Net income including noncontrolling interests	37	132
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for credit losses	162	3
Depreciation, amortization and accretion, net	80	111
Stock-based compensation—restricted stock units	15	9
Deferred income taxes	(25)	113
Net gains on sales of securities	(13)	(3)
Net decrease (increase) in trading account assets	(283)	(119)
Net decrease (increase) in other assets	402	(80)
Net increase (decrease) in trading account liabilities	(49)	50
Net increase (decrease) in other liabilities	79	181
Loans originated for sale	(519)	(362)
Net proceeds from sale of loans originated for sale	514	291
Pension and other benefits adjustment	(149)	(158)
Other, net	7	0
Total adjustments	221	36
Net cash provided by (used in) operating activities	258	168
Cash Flows from Investing Activities:
Proceeds from sales of securities available for sale	(1,658)	(324)
Proceeds from paydowns and maturities of securities available for sale	365	441
Purchases of securities available for sale	(529)	(485)
Proceeds from paydowns and maturities of securities held to maturity	360	377
Purchases of securities held to maturity	(866)	(1,146)
Proceeds from sales of loans	34	36
Net decrease (increase) in loans	(1,620)	(91)
Purchases of other investments	(46)	(77)
Other, net	(79)	(52)
Net cash provided by (used in) investing activities	(723)	(673)
Cash Flows from Financing Activities:
Net increase (decrease) in deposits	5,149	(3,263)
Net increase (decrease) in commercial paper and other short-term borrowings	(391)	771
Proceeds from issuance of long-term debt	0	2,697
Repayment of long-term debt	(500)	(817)
Other, net	(6)	(11)
Change in noncontrolling interests	8	(9)
Net cash provided by (used in) financing activities	4,260	(632)
Net change in cash and cash equivalents	3,795	(1,137)
Cash and cash equivalents at beginning of period	4,529	5,751
Cash and cash equivalents at end of period	8,324	4,614
Cash Paid During the Period For:
Income taxes, net	50	21
Supplemental Schedule of Noncash Investing and Financing Activities:
Net transfer of loans held for investment to loans held for sale	(81)
Transfer of loans held for investment to other real estate owned assets	$ 0	$ 3