Condensed Consolidated Statement of Changes in Equity - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjusted Balance	Revision of Prior Period, Accounting Standards Update, Adjustment	Common stock and paid-in capital	Common stock and paid-in capital Cumulative Effect, Period of Adoption, Adjusted Balance	Accumulated deficit	Accumulated deficit Cumulative Effect, Period of Adoption, Adjusted Balance	Accumulated deficit Revision of Prior Period, Accounting Standards Update, Adjustment	Accumulated other comprehensive income	Accumulated other comprehensive income Cumulative Effect, Period of Adoption, Adjusted Balance	Treasury stock	Treasury stock Cumulative Effect, Period of Adoption, Adjusted Balance
Common stock dividends, amount per share	$ 0.19
Equity at Dec. 31, 2019	$ 14,416	$ 13,399		$ 21,438	$ 21,438	$ (4,057)	$ (5,074)		$ 123	$ 123	$ (3,088)	$ (3,088)
Equity (Accounting Standards Update 2016-13) at Dec. 31, 2019			$ (1,017)					$ (1,017)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(319)					(319)
Share-based compensation	32			32
Other comprehensive income (loss)	583								583
Common stock repurchases	(104)										(104)
Common stock dividends	(72)					(72)
Equity at Mar. 31, 2020	$ 13,519			21,470		(5,465)			706		(3,192)
Common stock dividends, amount per share	$ 0.19
Equity at Dec. 31, 2020	$ 14,703			21,544		(4,278)			631		(3,194)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	796					796
Share-based compensation	22			22
Other comprehensive income (loss)	(604)								(604)
Common stock repurchases	(219)										(219)
Common stock dividends	(73)					(73)
Equity at Mar. 31, 2021	$ 14,625			$ 21,566		$ (3,555)			$ 27		$ (3,413)