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, 2016		169,724
Beginning Balance at Dec. 31, 2016	$ 10,411	$ 2	$ 8,892	$ (218)	$ 1,728	$ 7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared	(14)				(14)
Exercise of long-term incentive plan stock options and employee stock purchases	6		1	5
Exercise of long-term incentive plan stock options and employee stock purchases, shares		81
Purchase of treasury stock, shares		(191)
Purchase of treasury stock	(36)			(36)
Compensation costs:
Vested compensation awards, net, shares		575
Vested compensation awards, net	0
Compensation costs included in net income	79		79
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	0		2			(2)
Net income (loss)	833				833
Ending Balance, shares at Dec. 31, 2017		170,189
Ending Balance at Dec. 31, 2017	$ 11,279	$ 2	8,974	(249)	2,547	5
Compensation costs:
Dividends declared (usd per share)	$ 0.08
Dividends declared	$ (55)				(55)
Exercise of long-term incentive plan stock options and employee stock purchases	8		3	5
Exercise of long-term incentive plan stock options and employee stock purchases, shares		58
Purchase of treasury stock, shares		(1,272)
Purchase of treasury stock	(179)			(179)
Vested compensation awards, net, shares		524
Vested compensation awards, net	0
Compensation costs included in net income	85		85
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	(2)		0			(2)
Net income (loss)	975				978	(3)
Ending Balance, shares at Dec. 31, 2018		169,499
Ending Balance at Dec. 31, 2018	$ 12,111	$ 2	9,062	(423)	3,470	$ 0
Compensation costs:
Dividends declared (usd per share)	$ 0.32
Dividends declared	$ (201)				(201)
Exercise of long-term incentive plan stock options and employee stock purchases	6		(1)	7
Exercise of long-term incentive plan stock options and employee stock purchases, shares		64
Purchase of treasury stock, shares		(4,753)
Purchase of treasury stock	(653)			(653)
Vested compensation awards, net, shares		737
Vested compensation awards, net	0
Compensation costs included in net income	100		100
Net income (loss)	756				756
Ending Balance, shares at Dec. 31, 2019		165,547
Ending Balance at Dec. 31, 2019	$ 12,119	$ 2	$ 9,161	$ (1,069)	$ 4,025
Compensation costs:
Dividends declared (usd per share)	$ 1.20