CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Millions	Total	Adoption of new accounting standard [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member] Adoption of new accounting standard [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Balance at beginning of period at Dec. 31, 2018	$ 4,608		$ 107	$ 3	$ 4,049	$ 576		$ (106)	$ (21)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	329					292		37
Dividends declared:
Preferred stock	(6)					(6)
Common stock	(118)					(118)
Issuance of common stock	(1)				5				(6)
Restricted stock compensation	8				8
Balance at end of period at Sep. 30, 2019	4,820		107	3	4,062	744		(69)	(27)
Balance at beginning of period at Jun. 30, 2019	4,753		107	3	4,057	683		(72)	(25)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	106					103		3
Dividends declared:
Preferred stock	(2)					(2)
Common stock	(40)					(40)
Issuance of common stock	1				3				(2)
Restricted stock compensation	2				2
Balance at end of period at Sep. 30, 2019	4,820		107	3	4,062	744		(69)	(27)
Balance at beginning of period at Dec. 31, 2019	4,883	$ (50)	107	3	4,067	798	$ (50)	(65)	(27)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	253					214		39
Dividends declared:
Preferred stock	(6)					(6)
Common stock	(118)					(118)
Issuance of common stock	1				4				(3)
Repurchase of common stock	(25)								(25)
Restricted stock compensation	13				13
Balance at end of period at Sep. 30, 2020	4,951		107	3	4,084	838		(26)	(55)
Balance at beginning of period at Jun. 30, 2020	4,897		107	3	4,081	796		(35)	(55)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	92					83		9
Dividends declared:
Preferred stock	(2)					(2)
Common stock	(39)					(39)
Issuance of common stock	1				1
Restricted stock compensation	2				2
Balance at end of period at Sep. 30, 2020	$ 4,951		$ 107	$ 3	$ 4,084	$ 838		$ (26)	$ (55)