Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	Series A Preferred Stock [Member]	Series C Preferred Stock [Member]	Series D Preferred Stock [Member]	Preferred Stock [Member]	Preferred Stock [Member] Series A Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] Series A Preferred Stock [Member]	Capital Surplus [Member]	Capital Surplus [Member] Preferred Stock [Member]	Retained Earnings [Member]	Retained Earnings [Member] Series A Preferred Stock [Member]	Retained Earnings [Member] Series C Preferred Stock [Member]	Retained Earnings [Member] Series D Preferred Stock [Member]	Treasury Stock, at Cost [Member]	Treasury Stock, at Cost [Member] Series A Preferred Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests [Member]
Beginning Balance, Preferred Shares at Dec. 31, 2013					2,905,000
Beginning Balance, Common Shares at Dec. 31, 2013							890,724,000
Beginning Balance at Dec. 31, 2013					$ 291		$ 1,017		$ 4,022		$ 7,606				$ (2,281)		$ (352)	$ 17
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 907										900							7
Other comprehensive income (loss):
Net unrealized gains (losses) on securities available for sale, net of income taxes	59																59
Net unrealized gains (losses) on derivative financial instruments, net of income taxes	3																3
Foreign currency translation adjustments, net of income taxes	(20)																(20)
Net pension and postretirement benefit costs, net of income taxes	(46)																(46)
Deferred compensation									2
Cash dividends declared on common shares											(218)
Cash dividends declared on Noncumulative Series A Preferred Stock											(22)
Common shares repurchased (in shares)							(36,285,000)
Common shares repurchased															(484)
Common shares reissued (returned) for stock options and other employee benefit plans (in shares)							4,964,000
Common shares reissued (returned) for stock options and other employee benefit plans									(38)						84
LIHTC guaranteed funds put											7
Net contribution from (distribution to) noncontrolling interests																		(12)
Ending Balance, Preferred Shares at Dec. 31, 2014					2,905,000
Ending Balance, Common Shares at Dec. 31, 2014							859,403,000
Ending Balance at Dec. 31, 2014					$ 291		$ 1,017		3,986		8,273				(2,681)		(356)	12
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	920										916							4
Other comprehensive income (loss):
Net unrealized gains (losses) on securities available for sale, net of income taxes	(54)																(54)
Net unrealized gains (losses) on derivative financial instruments, net of income taxes	28																28
Foreign currency translation adjustments, net of income taxes	(24)																(24)
Net pension and postretirement benefit costs, net of income taxes	1																1
Deferred compensation									11
Cash dividends declared on common shares											(244)
Cash dividends declared on Noncumulative Series A Preferred Stock												$ (23)
Common shares repurchased (in shares)							(31,267,000)
Common shares repurchased															(448)
Series A Preferred Stock exchanged for common shares (in shares)						(5,000)		33,000
Series A Preferred Stock exchanged for common shares						$ (1)										$ 1
Common shares reissued (returned) for stock options and other employee benefit plans (in shares)							7,582,000
Common shares reissued (returned) for stock options and other employee benefit plans									(75)						128
Net contribution from (distribution to) noncontrolling interests																		(3)
Ending Balance, Preferred Shares at Dec. 31, 2015		2,900,234			2,900,000
Ending Balance, Common Shares at Dec. 31, 2015							835,751,000
Ending Balance at Dec. 31, 2015	10,759				$ 290		$ 1,017		3,922		8,922				(3,000)		(405)	13
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	790										791							(1)
Other comprehensive income (loss):
Net unrealized gains (losses) on securities available for sale, net of income taxes	(127)																(127)
Net unrealized gains (losses) on derivative financial instruments, net of income taxes	(34)																(34)
Foreign currency translation adjustments, net of income taxes	(1)																(1)
Net pension and postretirement benefit costs, net of income taxes	26																26
Deferred compensation									(4)
Cash dividends declared on common shares											(298)
Cash dividends declared on Noncumulative Series A Preferred Stock												$ (22)	$ (8)	$ (7)
Shares issued					$ 1,375		$ 240		2,591	$ (16)
Common shares repurchased (in shares)							(10,502,000)
Common shares repurchased															(140)
Issuance of Preferred Stock (in shares)					14,521,000		239,732,000
Common shares reissued (returned) for stock options and other employee benefit plans (in shares)							14,333,000
Common shares reissued (returned) for stock options and other employee benefit plans									(108)						236
Net contribution from (distribution to) noncontrolling interests																		(12)
Ending Balance, Preferred Shares at Dec. 31, 2016		2,900,234	14,000,000	21,000	17,421,000
Ending Balance, Common Shares at Dec. 31, 2016							1,079,314,000
Ending Balance at Dec. 31, 2016	$ 15,240				$ 1,665		$ 1,257		$ 6,385		$ 9,378				$ (2,904)		$ (541)	$ 0