Consolidated Statements of Changes In Shareholders' Equity - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Preferred stock	Common stock	Accumulated paid-in capital	Retained earnings	Retained earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated other comprehensive income (loss)
Balance at beginning of period at Dec. 31, 2019	$ 7,353	$ 20	$ 566	$ 0	$ 2,735	$ 4,009	$ 20	$ 43
Balance at beginning of period (in shares) at Dec. 31, 2019				165,057,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for the period	255					255
Other comprehensive income (loss), net of tax	289							289
Bank common stock repurchased (in shares)				(1,680,000)
Bank common stock repurchased	(75)				(75)
Net shares issued from stock warrant exercises (in shares)				1,000
Net activity under employee plans and related tax benefits (in shares)				631,000
Net activity under employee plans and related tax benefits	20				20
Dividends on preferred stock	(25)					(25)
Dividends on common stock	(169)					(169)
Balance at end of period at Sep. 30, 2020	7,668		566	$ 0	2,680	4,090		332
Balance at end of period (in shares) at Sep. 30, 2020				164,009,000
Balance at beginning of period at Jun. 30, 2020	7,575		566	$ 0	2,675	3,979		355
Balance at beginning of period (in shares) at Jun. 30, 2020				163,978,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for the period	175					175
Other comprehensive income (loss), net of tax	(23)							(23)
Net activity under employee plans and related tax benefits (in shares)				31,000
Net activity under employee plans and related tax benefits	5				5
Dividends on preferred stock	(9)					(9)
Dividends on common stock	(56)					(56)
Change in deferred compensation	1					1
Balance at end of period at Sep. 30, 2020	7,668		566	$ 0	2,680	4,090		332
Balance at end of period (in shares) at Sep. 30, 2020				164,009,000
Balance at beginning of period at Dec. 31, 2020	$ 7,886		566	$ 0	2,686	4,309		325
Balance at beginning of period (in shares) at Dec. 31, 2020	164,090,000			164,090,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for the period	$ 916					916
Other comprehensive income (loss), net of tax	(261)							(261)
Preferred stock redemption	$ (126)		(126)		3	(3)
Bank common stock repurchased (in shares)	(8,500,000)			(8,519,000)
Bank common stock repurchased	$ (475)				(475)
Net activity under employee plans and related tax benefits (in shares)				959,000
Net activity under employee plans and related tax benefits	31				31
Dividends on preferred stock	(23)					(23)
Dividends on common stock	(174)					(174)
Balance at end of period at Sep. 30, 2021	$ 7,774		440	$ 0	2,245	5,025		64
Balance at end of period (in shares) at Sep. 30, 2021	156,530,000			156,530,000
Balance at beginning of period at Jun. 30, 2021	$ 8,033		440	$ 0	2,565	4,853		175
Balance at beginning of period (in shares) at Jun. 30, 2021				162,248,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for the period	240					240
Other comprehensive income (loss), net of tax	(111)							(111)
Bank common stock repurchased (in shares)				(5,772,000)
Bank common stock repurchased	(325)				(325)
Net activity under employee plans and related tax benefits (in shares)				54,000
Net activity under employee plans and related tax benefits	5				5
Dividends on preferred stock	(6)					(6)
Dividends on common stock	(62)					(62)
Balance at end of period at Sep. 30, 2021	$ 7,774		$ 440	$ 0	$ 2,245	$ 5,025		$ 64
Balance at end of period (in shares) at Sep. 30, 2021	156,530,000			156,530,000