Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Preferred Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]
Balance at beginning of period at Dec. 31, 2018	$ 11,659	$ 0	$ 0	$ 8,058	$ (1,066)	$ 4,667
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	271					271
Other comprehensive income (loss)	42				42
Stock based compensation	11			11
Other	1					1
Balance at end of period at Mar. 31, 2019	11,984	0	0	8,069	(1,024)	4,939
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of accounting standard (Note 1)	(643)
Balance at beginning of period at Dec. 31, 2019	12,726	0	0	8,101	(1,119)	5,744
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	167					167
Other comprehensive income (loss)	(543)				(543)
Stock based compensation	9			9
Dividends paid (Note 11)	(400)					(400)
Balance at end of period at Mar. 31, 2020	$ 11,316	$ 0	$ 0	$ 8,110	$ (1,662)	$ 4,868