Consolidated Statement of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Accumulated Loss [Member]	Noncontrolling Interest [Member]	Parent Company [Member]	Parent Company [Member] Common Stock [Member]	Parent Company [Member] Treasury Stock [Member]	Parent Company [Member] Additional Paid-in Capital [Member]	Parent Company [Member] Accumulated Loss [Member]	Parent Company [Member] Accumulated Other Comprehensive Loss [Member]
Beginning balance at Dec. 31, 2016	$ 1,878,744		$ 891,246	$ 987,498	$ 875	$ (2,500)	$ 1,145,760	$ (94,270)	$ (62,367)
Beginning balance (in shares) at Dec. 31, 2016					87,521,651	110,964
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A common stock under equity incentive award plan					$ 3		(3)
Issuance of Class A common stock under equity incentive award plan, shares					231,311
Repurchase of shares for employee tax withholding	(97)			(97)		$ (97)
Repurchase of shares for employee tax withholding, shares						(4,182)
Stock-based compensation	2,768			2,768			2,768
Dividends declared	(72,934)			(72,934)			(72,934)
Contributions from noncontrolling interests	325,600	$ 0	325,600
Distributions to noncontrolling interests	(9,164)	0	(9,164)
Other	(270)		(127)	(143)			(143)
Net loss	(12,145)		(32,018)	19,873				19,873
Other comprehensive income (loss), net of tax	15,212		(107)	15,319					15,319
Ending balance at Jun. 30, 2017	2,127,714		1,175,430	952,284	$ 878	$ (2,597)	1,075,448	(74,397)	(47,048)
Ending balance (in shares) at Jun. 30, 2017					87,752,962	115,146
Beginning balance at Dec. 31, 2017	2,348,142		1,253,693	1,094,449	$ 980	$ (3,511)	1,234,846	(112,175)	(25,691)
Beginning balance (in shares) at Dec. 31, 2017					98,017,860	157,812
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A common stock under equity incentive award plan					$ 3		(3)
Issuance of Class A common stock under equity incentive award plan, shares					256,809
Repurchase of shares for employee tax withholding	(381)			(381)		$ (381)
Repurchase of shares for employee tax withholding, shares						(20,534)
Stock-based compensation	2,277			2,277			2,277
Dividends declared	(82,766)			(82,766)			(26,301)	(56,465)
Acquisitions	11,113	0	11,113
Distributions to noncontrolling interests	(21,274)	$ 0	(21,274)
Other	(209)			(209)			(209)
Net loss	(14,394)		(183,034)	168,640				168,640
Other comprehensive income (loss), net of tax	(8,817)		(1,752)	(7,065)					(7,065)
Ending balance at Jun. 30, 2018	$ 2,233,691		$ 1,058,746	$ 1,174,945	$ 983	$ (3,892)	$ 1,210,610	$ 0	$ (32,756)
Ending balance (in shares) at Jun. 30, 2018					98,274,669	178,346