CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN EQUITY - USD ($) shares in Thousands, $ in Millions	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]	Noncontrolling Interests [Member]	Total
Beginning balance at Dec. 31, 2017	$ 6	$ 4,933	$ 8,588	$ 8	$ (7,516)	$ 23	$ 6,042
Beginning balance, shares at Dec. 31, 2017	630,282				(196,964)
Equity roll forward
Adoption of new accounting standards			85	(5)			80
Consolidated net income			396			(1)	395
Other comprehensive income (loss), net of tax				(31)			(31)
Cash dividends declared			(206)				(206)
Equity-based compensation transactions, net of tax		(17)	4		$ 57		44
Equity-based compensation transaction, shares					1,483
Common stock repurchase program					$ (258)		(258)
Common stock repurchase program, shares					(3,031)
Other, net						(1)	(1)
Other, net, shares					1
Ending balance at Mar. 31, 2018	$ 6	4,916	8,867	(28)	$ (7,717)	21	6,065
Ending balance, shares at Mar. 31, 2018	630,282				(198,511)
Beginning balance at Dec. 31, 2018	$ 6	4,993	9,797	(87)	$ (8,434)	1	6,276
Beginning balance, shares at Dec. 31, 2018	630,282				(206,299)
Equity roll forward
Consolidated net income			347				347
Other comprehensive income (loss), net of tax				34			34
Cash dividends declared			(223)				(223)
Equity-based compensation transactions, net of tax		(15)	3		$ 58		46
Equity-based compensation transaction, shares					1,421
Common stock repurchase program					$ (64)		(64)
Common stock repurchase program, shares					(679)
Other, net						1	1
Other, net, shares					1
Ending balance at Mar. 31, 2019	$ 6	$ 4,978	$ 9,924	$ (53)	$ (8,440)	$ 2	$ 6,417
Ending balance, shares at Mar. 31, 2019	630,282				(205,556)