Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Millions		Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning balance at Dec. 31, 2018		$ 13,687	$ 0	$ 11,671	$ 10,039	$ (7,825)	$ (198)
Beginning balance (shares) at Dec. 31, 2018			688,000,000				8,000,000
Net (loss)/income		730			730
Dividends declared		(232)			(232)
Other comprehensive income		59				59
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes, $49.75 per share)	[1]	(8)		27			$ (35)
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes, $49.75 per share) (shares)	[1]		2,000,000				1,000,000
Stock purchased and retired		(1,325)		(444)	(881)
Stock purchased and retired (shares)			(26,000,000)
Ending balance at Mar. 31, 2019		12,911	$ 0	11,254	9,656	(7,766)	$ (233)
Ending balance (shares) at Mar. 31, 2019			664,000,000				9,000,000
Beginning balance at Dec. 31, 2019		15,358	$ 0	11,129	12,454	(7,989)	$ (236)
Beginning balance (shares) at Dec. 31, 2019			652,000,000				9,000,000
Net (loss)/income		(534)			(534)
Dividends declared		(257)			(257)
Other comprehensive income		91				91
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes, $49.75 per share)	[1]	(5)		29			$ (34)
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes, $49.75 per share) (shares)	[1]		1,000,000				1,000,000
Stock purchased and retired		(344)		(104)	(240)
Stock purchased and retired (shares)			(6,000,000)
Ending balance at Mar. 31, 2020		$ 14,309	$ 0	$ 11,054	$ 11,423	$ (7,898)	$ (270)
Ending balance (shares) at Mar. 31, 2020			647,000,000				10,000,000

[1] Weighted average price per share.