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			895			(1)	894
Other comprehensive income (loss), net of tax				(52)			(52)
Cash dividends declared			(406)				(406)
Equity-based compensation transactions, net		2	4		$ 62		68
Equity-based compensation transaction, shares					1,624
Common stock repurchase program					$ (550)		(550)
Common stock repurchase program, shares					(6,568)
Divestiture of noncontrolling interest						(19)	(19)
Other, net						(1)	(1)
Other, net, shares					2
Ending balance at Jun. 30, 2018	$ 6	4,935	9,166	(49)	$ (8,004)	2	6,056
Ending balance, shares at Jun. 30, 2018	630,282				(201,906)
Beginning balance at Mar. 31, 2018	$ 6	4,916	8,867	(28)	$ (7,717)	21	6,065
Beginning balance, shares at Mar. 31, 2018	630,282				(198,511)
Equity roll forward
Consolidated net income			499				499
Other comprehensive income (loss), net of tax				(21)			(21)
Cash dividends declared			(200)				(200)
Equity-based compensation transactions, net		19			$ 5		24
Equity-based compensation transaction, shares					141
Common stock repurchase program					$ (292)		(292)
Common stock repurchase program, shares					(3,537)
Divestiture of noncontrolling interest						(19)	(19)
Other, net, shares					1
Ending balance at Jun. 30, 2018	$ 6	4,935	9,166	(49)	$ (8,004)	2	6,056
Ending balance, shares at Jun. 30, 2018	630,282				(201,906)
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)
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)
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			728			1	729
Other comprehensive income (loss), net of tax				65			65
Cash dividends declared			(440)				(440)
Equity-based compensation transactions, net		5	3		$ 74		82
Equity-based compensation transaction, shares					1,808
Common stock repurchase program		(36)			$ (208)		(244)
Common stock repurchase program, shares					(1,993)
Other, net						(1)	(1)
Other, net, shares					2
Ending balance at Jun. 30, 2019	$ 6	4,962	10,088	(22)	$ (8,568)	1	6,467
Ending balance, shares at Jun. 30, 2019	630,282				(206,482)
Beginning balance at Mar. 31, 2019	$ 6	4,978	9,924	(53)	$ (8,440)	2	6,417
Beginning balance, shares at Mar. 31, 2019	630,282				(205,556)
Equity roll forward
Consolidated net income			381			1	382
Other comprehensive income (loss), net of tax				31			31
Cash dividends declared			(217)				(217)
Equity-based compensation transactions, net		20			$ 16		36
Equity-based compensation transaction, shares					387
Common stock repurchase program		(36)			$ (144)		(180)
Common stock repurchase program, shares					(1,314)
Other, net						(2)	(2)
Other, net, shares					1
Ending balance at Jun. 30, 2019	$ 6	$ 4,962	$ 10,088	$ (22)	$ (8,568)	$ 1	$ 6,467
Ending balance, shares at Jun. 30, 2019	630,282				(206,482)