CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Total	Total Cumulative Effect, Period of Adoption, Adjustment	Non-controlling interests subject to put provisions	Non-controlling interests subject to put provisions Cumulative Effect, Period of Adoption, Adjustment	Common stock	Additional paid-in capital	Retained earnings	Retained earnings Cumulative Effect, Period of Adoption, Adjustment	Treasury stock	Accumulated other comprehensive income (loss)	Accumulated other comprehensive income (loss) Cumulative Effect, Period of Adoption, Adjustment	Non-controlling interests not subject to put provisions	Non-controlling interests not subject to put provisions Cumulative Effect, Period of Adoption, Adjustment
Beginning Balance (in shares) at Dec. 31, 2017						182,462,000				0
Beginning balance at Dec. 31, 2017		$ 4,690,029	$ 0			$ 182	$ 1,042,899	$ 3,633,713	$ 8,368	$ 0	$ 13,235	$ (8,368)	$ 196,037
Temporary equity, beginning balance at Dec. 31, 2017				$ 1,011,360
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income				105,531
Distributions				(119,173)
Contributions				32,918
Acquisitions and divestitures				79,078
Partial purchases				(8,546)
Fair value remeasurements				23,473
Temporary equity, ending balance at Dec. 31, 2018				1,124,641
Comprehensive income:
Net income		159,394						159,394					68,115
Other comprehensive income	$ (39,791)	(39,791)									(39,791)
Stock purchase shares issued (in shares)						398,000
Stock purchase plan		17,398				$ 0	17,398
Stock award payment plan (in shares)						371,000
Stock award plan		(5,334)				$ 1	(5,335)
Stock-settled stock-based compensation expense		73,081					73,081
Changes in noncontrolling interest from:
Distributions													(77,268)
Contributions													19,393
Acquisitions and divestitures		3,546					3,546
Acquisitions and divestitures, noncontrolling interest													318
Partial purchases		(17,897)					(17,897)						(1,639)
Fair value remeasurements		(23,473)					(23,473)
Purchase of treasury stock (in shares)	(16,844,000)									(16,844,000)
Purchase of treasury stock	$ (1,153,511)	(1,153,511)								$ (1,153,511)
Retirement of treasury stock (in shares)						(16,844,000)				16,844,000
Retirement of treasury stock		0				$ (17)	(95,213)	(1,058,281)		$ 1,153,511
Ending balance at Dec. 31, 2018		3,703,442	$ 39,876		$ (38)	$ 166	995,006	2,743,194	$ 39,876	$ 0	(34,924)		204,956	$ (6)
Ending Balance (in shares) at Dec. 31, 2018						166,387,000				0
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income				143,413
Distributions				(155,011)
Contributions				35,572
Acquisitions and divestitures				(6,332)
Partial purchases				(11,394)
Fair value remeasurements				49,525
Temporary equity, ending balance at Dec. 31, 2019				1,180,376
Comprehensive income:
Net income		810,981						810,981					66,900
Other comprehensive income	$ (12,574)	(12,574)									(12,574)
Stock purchase shares issued (in shares)						315,000
Stock purchase plan		16,570				$ 1	16,569
Stock award payment plan (in shares)						161,000
Stock award plan		(3,290)				$ 0	(3,290)
Stock-settled stock-based compensation expense		67,549					67,549
Changes in noncontrolling interest from:
Distributions													(78,112)
Contributions													21,745
Acquisitions and divestitures, noncontrolling interest													(10,170)
Partial purchases		(37,145)					(37,145)						(19,480)
Fair value remeasurements		(49,525)					(49,525)
Purchase of treasury stock (in shares)	(41,020,000)									(41,020,000)
Purchase of treasury stock	$ (2,402,475)	(2,402,475)								$ (2,402,475)
Retirement of treasury stock (in shares)						(41,020,000)				41,020,000
Retirement of treasury stock		0				$ (41)	(240,121)	(2,162,313)		$ 2,402,475
Ending balance at Dec. 31, 2019	$ 2,319,242	2,133,409				$ 126	749,043	1,431,738		$ 0	(47,498)		185,833
Ending Balance (in shares) at Dec. 31, 2019	125,843,000					125,843,000				0
Increase (Decrease) in Temporary Equity [Roll Forward]
Net income				141,879
Distributions				(163,175)
Contributions				30,154
Acquisitions and divestitures				(3,215)
Partial purchases				(7,771)
Fair value remeasurements				151,780
Temporary equity, ending balance at Dec. 31, 2020				$ 1,330,028
Comprehensive income:
Net income		773,642						773,642					79,156
Other comprehensive income	$ (18,656)	(18,656)									(18,656)
Stock purchase shares issued (in shares)						222,000
Stock purchase plan		17,148				$ 0	17,148
Stock award payment plan (in shares)						345,000
Stock award plan		(17,801)				$ 0	(17,801)
Stock-settled stock-based compensation expense		90,007					90,007
Changes in noncontrolling interest from:
Distributions													(89,943)
Contributions													12,812
Acquisitions and divestitures, noncontrolling interest													(248)
Partial purchases		4,364					4,364						(4,424)
Fair value remeasurements		(151,780)					(151,780)
Purchase of treasury stock (in shares)	(16,477,000)									(16,477,000)
Purchase of treasury stock	$ (1,446,767)	(1,446,767)								$ (1,446,767)
Retirement of treasury stock (in shares)						(16,477,000)				16,477,000
Retirement of treasury stock		0				$ (16)	(93,908)	(1,352,843)		$ 1,446,767
Ending balance at Dec. 31, 2020	$ 1,566,752	$ 1,383,566				$ 110	$ 597,073	$ 852,537		$ 0	$ (66,154)		$ 183,186
Ending Balance (in shares) at Dec. 31, 2020	109,933,000					109,933,000				0