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	883			852			31
Other comprehensive income (loss), net of taxes	(3)				(3)
Dividends declared	(226)			(226)
Distributions to noncontrolling interest partners	(31)						(31)
Issuance of common stock under benefit plans, shares		1.0
Issuance of common stock under benefit plans	17		7			10
Stock-based compensation expense	63		63
Exercise of stock options, shares		2.0
Exercise of stock options	144		22			$ 122
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 Sep. 30, 2020		135.0
Balance, value at Sep. 30, 2020	6,446	$ 2	2,801	8,800	(42)	(5,161)	46
Balance, Value at Dec. 31, 2019	76
Redeemable Non-controlling Interest [Abstract]
Net income	7
Distributions to noncontrolling interest partners	(3)
Balance, Value at Sep. 30, 2020	80
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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	586			568			18
Other comprehensive income (loss), net of taxes	13				13
Dividends declared	(75)			(75)
Distributions to noncontrolling interest partners	(22)						(22)
Issuance of common stock under benefit plans, shares		1.0
Issuance of common stock under benefit plans	4		1			3
Stock-based compensation expense	32		32
Exercise of stock options	27		4			23
Balance, shares at Sep. 30, 2020		135.0
Balance, value at Sep. 30, 2020	6,446	$ 2	2,801	8,800	(42)	(5,161)	46
Balance, Value at Jun. 30, 2020	77
Redeemable Non-controlling Interest [Abstract]
Net income	5
Distributions to noncontrolling interest partners	(2)
Balance, Value at Sep. 30, 2020	80
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	1,658			1,605			53
Other comprehensive income (loss), net of taxes	8				8
Dividends declared	(233)			(233)
Distributions to noncontrolling interest partners	(63)						(63)
Issuance of common stock under benefit plans	17		(25)			42
Stock-based compensation expense	60		60
Exercise of stock options, shares		2.0
Exercise of stock options	108		19			89
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)
Retirement of treasury stock	0		(649)	(3,342)		3,991
Balance, shares at Sep. 30, 2021		123.0
Balance, value at Sep. 30, 2021	6,432	$ 2	1,936	7,333	(13)	(2,866)	40
Balance, Value at Dec. 31, 2020	82
Redeemable Non-controlling Interest [Abstract]
Net income	9
Distributions to noncontrolling interest partners	(12)
Balance, Value at Sep. 30, 2021	79
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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	524			505			19
Other comprehensive income (loss), net of taxes	(3)				(3)
Dividends declared	(76)			(76)
Distributions to noncontrolling interest partners	(20)						(20)
Issuance of common stock under benefit plans	6		2			4
Stock-based compensation expense	21		21
Exercise of stock options, shares		1.0
Exercise of stock options	40		7			33
Retirement of treasury stock	0		(649)	(3,342)		3,991
Balance, shares at Sep. 30, 2021		123.0
Balance, value at Sep. 30, 2021	6,432	$ 2	$ 1,936	$ 7,333	$ (13)	$ (2,866)	$ 40
Balance, Value at Jun. 30, 2021	78
Redeemable Non-controlling Interest [Abstract]
Net income	3
Distributions to noncontrolling interest partners	(2)
Balance, Value at Sep. 30, 2021	$ 79