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	80					80
Other comprehensive income (loss), net of tax	312							312
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)				600,000
Net activity under employee plans and related tax benefits	15				15
Dividends on preferred stock	(17)					(17)
Dividends on common stock	(112)					(112)
Change in deferred compensation	(1)					(1)
Balance at end of period at Jun. 30, 2020	7,575		566	$ 0	2,675	3,979		355
Balance at end of period (in shares) at Jun. 30, 2020				163,978,000
Balance at beginning of period at Mar. 31, 2020	7,472		566	$ 0	2,668	3,979		259
Balance at beginning of period (in shares) at Mar. 31, 2020				163,852,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for the period	66					66
Other comprehensive income (loss), net of tax	96							96
Bank common stock repurchased (in shares)				(11,000)
Net activity under employee plans and related tax benefits (in shares)				137,000
Net activity under employee plans and related tax benefits	7				7
Dividends on preferred stock	(9)					(9)
Dividends on common stock	(56)					(56)
Change in deferred compensation	(1)					(1)
Balance at end of period at Jun. 30, 2020	7,575		566	$ 0	2,675	3,979		355
Balance at end of period (in shares) at Jun. 30, 2020				163,978,000
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	$ 676					676
Other comprehensive income (loss), net of tax	(150)							(150)
Preferred stock redemption	$ (126)		(126)		3	(3)
Bank common stock repurchased (in shares)	(2,700,000)			(2,747,000)
Bank common stock repurchased	$ (151)				(151)
Net activity under employee plans and related tax benefits (in shares)				905,000
Net activity under employee plans and related tax benefits	27				27
Dividends on preferred stock	(17)					(17)
Dividends on common stock	(113)					(113)
Change in deferred compensation	1					1
Balance at end of period at Jun. 30, 2021	$ 8,033		440	$ 0	2,565	4,853		175
Balance at end of period (in shares) at Jun. 30, 2021	162,248,000			162,248,000
Balance at beginning of period at Mar. 31, 2021	$ 7,933		566	$ 0	2,653	4,566		148
Balance at beginning of period (in shares) at Mar. 31, 2021				163,800,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income for the period	354					354
Other comprehensive income (loss), net of tax	27							27
Preferred stock redemption	(126)		(126)		3	(3)
Bank common stock repurchased (in shares)				(1,735,000)
Bank common stock repurchased	(101)				(101)
Net activity under employee plans and related tax benefits (in shares)				183,000
Net activity under employee plans and related tax benefits	10				10
Dividends on preferred stock	(9)					(9)
Dividends on common stock	(56)					(56)
Change in deferred compensation	1					1
Balance at end of period at Jun. 30, 2021	$ 8,033		$ 440	$ 0	$ 2,565	$ 4,853		$ 175
Balance at end of period (in shares) at Jun. 30, 2021	162,248,000			162,248,000