Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Millions, $ 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				8
Net (loss)/income		730			730
Dividends declared		(232)			(232)
Other comprehensive income/(loss)		59				59
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes)	[1]	(8)		27			$ (35)
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes) (shares)	[1]		2				1
Stock purchased and retired		(1,325)		(444)	(881)
Stock purchased and retired (shares)			(26)
Ending balance at Mar. 31, 2019		12,911	$ 0	11,254	9,656	(7,766)	$ (233)
Ending balance (shares) at Mar. 31, 2019			664				9
Beginning balance at Dec. 31, 2018		13,687	$ 0	11,671	10,039	(7,825)	$ (198)
Beginning balance (shares) at Dec. 31, 2018			688				8
Net (loss)/income		2,173
Ending balance at Jun. 30, 2019		13,958	$ 0	11,201	10,686	(7,694)	$ (235)
Ending balance (shares) at Jun. 30, 2019			659				9
Beginning balance at Mar. 31, 2019		12,911	$ 0	11,254	9,656	(7,766)	$ (233)
Beginning balance (shares) at Mar. 31, 2019			664				9
Net (loss)/income		1,443			1,443
Dividends declared		(229)			(229)
Other comprehensive income/(loss)		72				72
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes)	[1]	29		31			$ (2)
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes) (shares)	[1]		0				0
Stock purchased and retired		(268)		(84)	(184)
Stock purchased and retired (shares)			(5)
Ending balance at Jun. 30, 2019		13,958	$ 0	11,201	10,686	(7,694)	$ (235)
Ending balance (shares) at Jun. 30, 2019			659				9
Beginning balance at Dec. 31, 2019		15,358	$ 0	11,129	12,454	(7,989)	$ (236)
Beginning balance (shares) at Dec. 31, 2019			652				9
Net (loss)/income		(534)			(534)
Dividends declared		(257)			(257)
Other comprehensive income/(loss)		91				91
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes)	[1]	(5)		29			$ (34)
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes) (shares)	[1]		1				1
Stock purchased and retired		(344)		(104)	(240)
Stock purchased and retired (shares)			(6)
Ending balance at Mar. 31, 2020		14,309	$ 0	11,054	11,423	(7,898)	$ (270)
Ending balance (shares) at Mar. 31, 2020			647				10
Beginning balance at Dec. 31, 2019		15,358	$ 0	11,129	12,454	(7,989)	$ (236)
Beginning balance (shares) at Dec. 31, 2019			652				9
Net (loss)/income		(6,251)
Ending balance at Jun. 30, 2020		8,690	$ 0	11,192	5,706	(7,937)	$ (271)
Ending balance (shares) at Jun. 30, 2020			647				10
Beginning balance at Mar. 31, 2020		14,309	$ 0	11,054	11,423	(7,898)	$ (270)
Beginning balance (shares) at Mar. 31, 2020			647				10
Net (loss)/income		(5,717)			(5,717)
Other comprehensive income/(loss)		(39)				(39)
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes)	[1]	37		38			$ (1)
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes) (shares)	[1]		0				0
CARES Act warrant issuance		100		100
Ending balance at Jun. 30, 2020		$ 8,690	$ 0	$ 11,192	$ 5,706	$ (7,937)	$ (271)
Ending balance (shares) at Jun. 30, 2020			647				10

[1] Weighted average price per share.