CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Non- controlling Interests subject to put provisions	Common stock	Common stock Stock Appreciation Rights	Additional paid-in capital	Additional paid-in capital Stock Appreciation Rights	Retained earnings	Treasury stock	Treasury stock Stock Appreciation Rights	Accumulated other comprehensive income (loss)	Total	Non-controlling interests not subject to put provisions
Beginning Balance at Dec. 31, 2013		$ 697,300	$ 213		$ 1,070,922		$ 3,363,989			$ (2,645)	$ 4,432,479	$ 173,062
Beginning Balance (in shares) at Dec. 31, 2013			213,163,000
Comprehensive income:
Net income		88,425					723,114				723,114	51,791
Other comprehensive income (loss)	$ (22,372)									(22,372)	(22,372)
Stock purchase shares issued					19,010						19,010
Stock purchase shares issued (in shares)			298,000
Stock-settled shares issued			$ 1	$ 2	(28)	$ (2)					(27)
Stock-settled shares issued (in shares)			304,000	1,876,000
Stock-based compensation expense					54,969						54,969
Excess tax benefits from stock awards exercised					45,271						45,271
Distributions to noncontrolling interests		(93,884)										(55,455)
Contributions from noncontrolling interests		41,876										22,779
Sales and assumptions of additional noncontrolling interests		25,220			355						355	4,165
Purchases from noncontrolling interests		(6,111)			(5,357)						(5,357)	(6,544)
Other reclassification					210						210
Changes in fair value of noncontrolling interests		77,139			(77,139)						(77,139)
Ending Balance at Dec. 31, 2014		829,965	$ 216		1,108,211		4,087,103			(25,017)	5,170,513	189,798
Ending Balance (in shares) at Dec. 31, 2014			215,641,000
Comprehensive income:
Net income		96,510					269,732				269,732	61,168
Other comprehensive income (loss)	(34,809)									(34,809)	(34,809)
Stock purchase shares issued					(6,079)			$ 30,608			24,529
Stock purchase shares issued (in shares)								414,000
Stock-settled shares issued				$ 1		(1)
Stock-settled shares issued (in shares)			348,000	1,131,000
Stock-based compensation expense					56,899						56,899
Excess tax benefits from stock awards exercised					28,157						28,157
Distributions to noncontrolling interests		(103,355)										(71,280)
Contributions from noncontrolling interests		25,795										28,849
Sales and assumptions of additional noncontrolling interests		10,654										6,875
Purchases from noncontrolling interests		(8,538)			(55,826)						(55,826)	(2,018)
Changes in fair value of noncontrolling interests		13,035			(13,035)						(13,035)
Purchase of treasury stock	$ (575,380)							$ (575,380)			(575,380)
Purchase of treasury stock (in shares)	(7,779,958)							(7,780,000)
Ending Balance at Dec. 31, 2015	$ 5,084,172	864,066	$ 217		1,118,326		4,356,835	$ (544,772)		(59,826)	4,870,780	213,392
Ending Balance (in shares) at Dec. 31, 2015	209,754,247		217,120,000					(7,366,000)
Comprehensive income:
Net income		99,834					879,874				879,874	53,374
Other comprehensive income (loss)	$ (29,627)									(29,817)	(29,817)	190
Stock purchase shares issued			$ 1		23,902						23,903
Stock purchase shares issued (in shares)			438,000
Stock-settled shares issued					(19,815)	$ (36,685)		$ 19,815	$ 36,685
Stock-settled shares issued (in shares)			4,000	218,000				276,000	513,000
Stock-based compensation expense					37,970						37,970
Excess tax benefits from stock awards exercised					13,251						13,251
Distributions to noncontrolling interests		(111,092)										(81,309)
Contributions from noncontrolling interests		33,517										14,073
Sales and assumptions of additional noncontrolling interests		28,874			3,423						3,423	2,585
Purchases from noncontrolling interests		(6,660)			(13,105)						(13,105)	(1,747)
Changes in fair value of noncontrolling interests		65,855			(65,855)						(65,855)
Reclassifications and expirations of noncontrolling interests subject to puts		(1,136)										1,136
Purchase of treasury stock	$ (1,072,377)							$ (1,072,377)			(1,072,377)
Purchase of treasury stock (in shares)	(16,649,090)							(16,649,000)
Retirement of treasury stock			$ (23)		(34,230)		(1,526,396)	$ 1,560,649
Retirement of treasury stock (in shares)			(23,226,000)					23,226,000
Ending Balance at Dec. 31, 2016	$ 4,849,741	$ 973,258	$ 195		$ 1,027,182		$ 3,710,313			$ (89,643)	$ 4,648,047	$ 201,694
Ending Balance (in shares) at Dec. 31, 2016	194,554,491		194,554,000