Consolidated Statements Of Changes In Shareholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Total
Balance at beginning of period at Dec. 31, 2018	$ 7,578		$ 566	$ 0	$ 3,806	$ 3,456		$ (250)
Balance at beginning of period (Accounting Standards Update 2017-08 [Member]) at Dec. 31, 2018		$ (3)					$ (3)
Balance at beginning of period (in shares) at Dec. 31, 2018				187,554
Net income for the period	411					411
Other comprehensive income, net of tax	275							275
Bank common stock repurchased (in shares)				(11,363)
Bank common stock repurchased	(551)				(551)
Net shares issued from stock warrant exercises (in shares)				8
Net activity under employee plans and related tax benefits (in shares)				736
Net activity under employee plans and related tax benefits	16				16
Dividends on preferred stock	(17)					(17)
Dividends on common stock	$ (110)					(110)
Dividends on common stock (in dollars per share)	$ 0.60
Balance at end of period (in shares) at Jun. 30, 2019				176,935
Balance at end of period at Jun. 30, 2019	$ 7,599		566	$ 0	3,271	3,737		25
Balance at beginning of period at Mar. 31, 2019	7,588		566	$ 0	3,541	3,603		(122)
Balance at beginning of period (in shares) at Mar. 31, 2019				182,513
Net income for the period	198					198
Other comprehensive income, net of tax	147							147
Bank common stock repurchased (in shares)				(5,857)
Bank common stock repurchased	(276)				(276)
Net shares issued from stock warrant exercises (in shares)				7
Net activity under employee plans and related tax benefits (in shares)				272
Net activity under employee plans and related tax benefits	6				6
Dividends on preferred stock	(10)					(10)
Dividends on common stock	$ (54)					(54)
Dividends on common stock (in dollars per share)	$ 0.30
Balance at end of period (in shares) at Jun. 30, 2019				176,935
Balance at end of period at Jun. 30, 2019	$ 7,599		566	$ 0	3,271	3,737		25
Balance at beginning of period at Dec. 31, 2019	$ 7,353		566	$ 0	2,735	4,009		43
Balance at beginning of period (Accounting Standards Update 2016-13 [Member]) at Dec. 31, 2019		20					20
Balance at beginning of period (in shares) at Dec. 31, 2019	165,057			165,057
Bank common stock repurchased (in shares)	(1,700)
Balance at end of period (in shares) at Mar. 31, 2020				163,852
Balance at end of period at Mar. 31, 2020	$ 7,472		566	$ 0	2,668	3,979		259
Balance at beginning of period at Dec. 31, 2019	$ 7,353		566	$ 0	2,735	4,009		43
Balance at beginning of period (Accounting Standards Update 2016-13 [Member]) at Dec. 31, 2019		$ 20					$ 20
Balance at beginning of period (in shares) at Dec. 31, 2019	165,057			165,057
Net income for the period	$ 80					80
Other comprehensive income, net of tax	312							312
Bank common stock repurchased (in shares)				(1,680)
Bank common stock repurchased	(75)				(75)
Net shares issued from stock warrant exercises (in shares)				1
Net activity under employee plans and related tax benefits (in shares)				600
Net activity under employee plans and related tax benefits	15				15
Dividends on preferred stock	(17)					(17)
Dividends on common stock	$ (112)					(112)
Dividends on common stock (in dollars per share)	$ 0.68
Change in deferred compensation	$ (1)					(1)
Balance at end of period (in shares) at Jun. 30, 2020	163,978			163,978
Balance at end of period at Jun. 30, 2020	$ 7,575		566	$ 0	2,675	3,979		355
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
Net income for the period	66					66
Other comprehensive income, net of tax	96							96
Bank common stock repurchased (in shares)				(11)
Bank common stock repurchased	0				0
Net activity under employee plans and related tax benefits (in shares)				137
Net activity under employee plans and related tax benefits	7				7
Dividends on preferred stock	(9)					(9)
Dividends on common stock	$ (56)					(56)
Dividends on common stock (in dollars per share)	$ 0.34
Change in deferred compensation	$ (1)					(1)
Balance at end of period (in shares) at Jun. 30, 2020	163,978			163,978
Balance at end of period at Jun. 30, 2020	$ 7,575		$ 566	$ 0	$ 2,675	$ 3,979		$ 355