Condensed Consolidated Statement of Changes in Equity - USD ($) $ in Millions	Total	Common stock and paid-in capital	Preferred stock	Retained earnings	Accumulated other comprehensive income (loss)	Treasury stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity	$ 13,439	$ 21,100	$ 696	$ (8,110)		$ (16)
Accumulated other comprehensive loss	$ (231)				$ (231)
Common stock dividends, amount per share	$ 0.16
Net income	$ 1,067			1,067
Preferred stock dividends	30			30
Preferred stock redemption	696		696
Share-based compensation	66	66
Other comprehensive income (loss)	(110)				(110)
Common stock repurchases	(341)					(341)
Common stock dividends	(78)			(78)
Equity	13,317	21,166	0	(7,151)		(357)
Accumulated other comprehensive loss	$ (341)				(341)
Common stock dividends, amount per share	$ 0.40
Net income	$ 929			929
Preferred stock dividends	0
Share-based compensation	79	79
Other comprehensive income (loss)	106				106
Common stock repurchases	(753)					(753)
Common stock dividends	(184)			(184)
Equity	13,494	21,245	0	(6,406)		(1,110)
Accumulated other comprehensive loss	$ (235)				(235)
Common stock dividends, amount per share	$ 0.56
Net income	$ 1,263			1,263
Preferred stock dividends	0
Share-based compensation	100	100
Other comprehensive income (loss)	(289)				(289)
Common stock repurchases	(939)					(939)
Common stock dividends	(242)			(242)
Equity	13,268	$ 21,345	$ 0	$ (5,489)		$ (2,049)
Accumulated other comprehensive loss	(539)				$ (539)
Cumulative effect of changes in accounting principles, net of tax | Accounting Standards Update 2014-09	(126)
Cumulative effect of changes in accounting principles, net of tax | Accounting Standards Update 2016-01	(20)
Cumulative effect of changes in accounting principles, net of tax | Accounting Standards Update 2018-02	$ (42)