Consolidated Statements Of Stockholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Noncontrolling Interests
Beginning Balance, shares at Dec. 31, 2017		170,189
Beginning Balance at Dec. 31, 2017	$ 11,279	$ 2	$ 8,974	$ (249)	$ 2,547	$ 5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared (usd per share)	$ 0.32
Dividends declared	$ (55)				(55)
Exercise of long-term incentive plan stock options and employee stock purchases, shares		58
Exercise of long-term incentive plan stock options and employee stock purchases	8		3	5
Purchase of treasury stock, shares		(1,272)
Purchase of treasury stock	(179)			(179)
Compensation costs:
Vested compensation awards, net, shares		524
Vested compensation awards, net	0
Compensation costs included in net income	85		85
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	(2)		0			2
Net income (loss)	975				978	(3)
Ending Balance at Dec. 31, 2018	$ 12,111	$ 2	9,062	(423)	3,470	0
Ending Balance, shares at Dec. 31, 2018		169,499
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared (usd per share)	$ 1.20
Dividends declared	$ (201)				(201)
Exercise of long-term incentive plan stock options and employee stock purchases, shares		64
Exercise of long-term incentive plan stock options and employee stock purchases	6		(1)	7
Purchase of treasury stock, shares		(4,753)
Purchase of treasury stock	(653)			(653)
Compensation costs:
Vested compensation awards, net, shares		737
Vested compensation awards, net	0
Compensation costs included in net income	100		100
Net income (loss)	773				773	0
Ending Balance at Dec. 31, 2019	$ 12,136	$ 2	9,161	(1,069)	4,042	$ 0
Ending Balance, shares at Dec. 31, 2019		165,547
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared (usd per share)	$ 2.20
Dividends declared	$ (364)				364
Equity component	230		230
Capped call	(113)		(113)
Deferred tax provision	(25)		(25)
Exercise of long-term incentive plan stock options and employee stock purchases, shares		98
Exercise of long-term incentive plan stock options and employee stock purchases	9		(2)	11
Purchase of treasury stock, shares		(1,634)
Purchase of treasury stock	(176)			(176)
Compensation costs:
Vested compensation awards, net, shares		466
Vested compensation awards, net	0
Compensation costs included in net income	72		72
Net income (loss)	(200)				(200)
Ending Balance at Dec. 31, 2020	$ 11,569	$ 2	$ 9,323	$ (1,234)	$ 3,478
Ending Balance, shares at Dec. 31, 2020		164,477