CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock, at Cost	Non-controlling Interests
Balance, shares at Dec. 31, 2019		133.0
Balance, value at Dec. 31, 2019	$ 5,687	$ 2	$ 2,722	$ 8,174	$ (39)	$ (5,218)	$ 46
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	297			284			13
Other comprehensive income (loss), net of taxes	(16)				(16)
Dividends declared	(151)			(151)
Distributions to noncontrolling interest partners	(9)						(9)
Issuance of common stock under benefit plans	13		6			7
Stock-based compensation expense	31		31
Exercise of stock options, shares		2.0
Exercise of stock options	117		18			$ 99
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans	(13)		(13)
Purchases of treasury stock, shares		(1.0)				(0.7)
Purchases of treasury stock	(75)					$ (75)
Balance, shares at Jun. 30, 2020		134.0
Balance, value at Jun. 30, 2020	5,881	$ 2	2,764	8,307	(55)	(5,187)	50
Balance, Value at Dec. 31, 2019	76
Redeemable Non-controlling Interest [Abstract]
Net income	2
Distributions to noncontrolling interest partners	(1)
Balance, Value at Jun. 30, 2020	77
Balance, shares at Mar. 31, 2020		134.0
Balance, value at Mar. 31, 2020	5,703	$ 2	2,738	8,197	(58)	(5,222)	46
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	192			185			7
Other comprehensive income (loss), net of taxes	3				3
Dividends declared	(75)			(75)
Distributions to noncontrolling interest partners	(3)						(3)
Issuance of common stock under benefit plans	7		3			4
Stock-based compensation expense	17		17
Exercise of stock options	37		6			31
Balance, shares at Jun. 30, 2020		134.0
Balance, value at Jun. 30, 2020	5,881	$ 2	2,764	8,307	(55)	(5,187)	50
Balance, Value at Mar. 31, 2020	76
Redeemable Non-controlling Interest [Abstract]
Net income	1
Balance, Value at Jun. 30, 2020	77
Balance, shares at Dec. 31, 2020		133.0
Balance, value at Dec. 31, 2020	6,809	$ 2	2,841	9,303	(21)	(5,366)	50
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,134			1,100			34
Other comprehensive income (loss), net of taxes	11				11
Dividends declared	(157)			(157)
Distributions to noncontrolling interest partners	(43)						(43)
Issuance of common stock under benefit plans	11		(27)			38
Stock-based compensation expense	39		39
Exercise of stock options, shares		1.0
Exercise of stock options	68		12			56
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans	(22)		(10)			$ (12)
Purchases of treasury stock, shares		(12.0)				(12.5)
Purchases of treasury stock	(1,910)		(300)			$ (1,610)
Balance, shares at Jun. 30, 2021		122.0
Balance, value at Jun. 30, 2021	5,940	$ 2	2,555	10,246	(10)	(6,894)	41
Balance, Value at Dec. 31, 2020	82
Redeemable Non-controlling Interest [Abstract]
Net income	6
Distributions to noncontrolling interest partners	(10)
Balance, Value at Jun. 30, 2021	78
Balance, shares at Mar. 31, 2021		131.0
Balance, value at Mar. 31, 2021	6,790	$ 2	2,824	9,690	(31)	(5,740)	45
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	648			631			17
Other comprehensive income (loss), net of taxes	21				21
Dividends declared	(75)			(75)
Distributions to noncontrolling interest partners	(21)						(21)
Issuance of common stock under benefit plans	6		2			4
Stock-based compensation expense	21		21
Exercise of stock options	51		9			42
Shares to cover employee payroll tax withholdings on stock issued under stock-based compensation plans	(1)		(1)
Purchases of treasury stock, shares		(9.0)
Purchases of treasury stock	(1,500)		(300)			(1,200)
Balance, shares at Jun. 30, 2021		122.0
Balance, value at Jun. 30, 2021	5,940	$ 2	$ 2,555	$ 10,246	$ (10)	$ (6,894)	$ 41
Balance, Value at Mar. 31, 2021	79
Redeemable Non-controlling Interest [Abstract]
Net income	2
Distributions to noncontrolling interest partners	(3)
Balance, Value at Jun. 30, 2021	$ 78