CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Noncontrolling Interests	Redeemable Noncontrolling Interest	Total
Balances at Dec. 31, 2014	$ 635	$ (398,898)	$ 1,083,435	$ 2,227,843	$ (117,488)	$ 126,340	$ 2,795,527
Common Stock, Shares, Outstanding, Beginning Balance at Dec. 31, 2014	241,449,000
Treasury Stock, Shares, Beginning Balance at Dec. 31, 2014		19,971,000
Proceeds from exercise of stock options, including related tax effect	$ 1	$ (211)	10,975				10,765
Proceeds from exercise of stock options, including related tax effect (in shares)	737,000	10,000
Dividends declared				(133,227)			(133,227)
Noncontrolling investors, net				1,082	(2,269)		(1,187)
Equity-based compensation	$ 2	$ 2,654	15,843	(96)			18,403
Equity-based compensation (in shares)	904,000	(133,000)
Comprehensive and net income (loss)				(130,311)	(14,859)		(145,170)
Balances at Dec. 31, 2015	$ 638	$ (396,455)	1,110,253	1,965,291	(134,616)	126,340	2,545,111
Common Stock, Shares, Outstanding, Ending Balance at Dec. 31, 2015	243,090,000
Treasury Stock, Shares, Ending Balance at Dec. 31, 2015		19,848,000
Proceeds from exercise of stock options, including related tax effect	$ 3		9,834				9,837
Proceeds from exercise of stock options, including related tax effect (in shares)	556,000	12,000
Dividends declared				(136,472)			(136,472)
Noncontrolling investors, net				(356)	7,164	(15,100)	6,808
Share repurchases		$ (25,034)					$ (25,034)
Share repurchases (in shares)	(732,000)	732,000					732,000
Equity-based compensation		$ 4,660	12,662	(119)			$ 17,203
Equity-based compensation (in shares)	871,000	(247,000)
Comprehensive and net income (loss)				382,115	(22,109)		360,006
Balances at Dec. 31, 2016	$ 641	$ (416,829)	1,132,749	2,210,459	(149,561)	111,240	$ 2,777,459
Common Stock, Shares, Outstanding, Ending Balance at Dec. 31, 2016	243,785,000						243,785,485
Treasury Stock, Shares, Ending Balance at Dec. 31, 2016		20,345,000					20,345,059
Dividends declared				(148,231)			$ (148,231)
Share repurchases		$ (252,242)					$ (252,242)
Share repurchases (in shares)	(7,439,000)	7,439,000					7,400,000
Equity-based compensation	$ 3	$ 3,774	8,785	(276)			$ 12,286
Equity-based compensation (in shares)	1,051,000	(178,000)
Comprehensive and net income (loss)				812,741	(6,945)		805,796
Balances at Dec. 31, 2017	$ 644	$ (665,297)	$ 1,141,534	$ 2,874,693	$ (156,506)	$ 111,240	$ 3,195,068
Common Stock, Shares, Outstanding, Ending Balance at Dec. 31, 2017	237,397,000						237,396,839
Treasury Stock, Shares, Ending Balance at Dec. 31, 2017		27,606,000					27,606,294