Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Adoption of New Accounting Standard	Preferred Stock	Common Stock	Additional Paid-In Capital	Retained Earnings	Retained Earnings Adoption of New Accounting Standard	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Balance at beginning of period at Dec. 31, 2017	$ 4,409		$ 107	$ 3	$ 4,033	$ 368		$ (83)	$ (19)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	350					373		(23)
Dividends declared:
Preferred stock	(8)					(8)
Common stock	(157)					(157)
Issuance of common stock	4				6				(2)
Restricted stock compensation	10				10
Balance at end of period at Dec. 31, 2018	4,608		107	3	4,049	576		(106)	(21)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	428					387		41
Dividends declared:
Preferred stock	(8)					(8)
Common stock	(157)					(157)
Issuance of common stock	0				6				(6)
Restricted stock compensation	12				12
Balance at end 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 (loss)	312					286		26
Dividends declared:
Preferred stock	(8)					(8)
Common stock	(157)					(157)
Issuance of common stock	1				4				(3)
Repurchase of common stock	(38)								(38)
Restricted stock compensation	16				16
Balance at end of period at Dec. 31, 2020	$ 4,959		$ 107	$ 3	$ 4,087	$ 869		$ (39)	$ (68)