Condensed Consolidated Statements of Changes in Equity (Unaudited) - USD ($) $ in Thousands	Class A common stock	Class B common stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Total
Balance at beginning of the period at Dec. 31, 2015	$ 205	$ 312	$ (7,616)	$ 190,703	$ (15,338)	$ 108	$ 89,044	$ 257,418
Balance at beginning of the period (in shares) at Dec. 31, 2015	20,536,740	31,229,236	(263,622)
Changes in Equity
Net income (loss)					23,352		63,785	87,137
Equity-based compensation	$ 3			53,934			2,376	56,313
Equity-based compensation (in shares)	253,757	(2,132)
Other comprehensive income (loss)						(552)	(921)	(1,473)
Dividends declared and distributions				10,276	(45,610)		(100,417)	(135,751)
Treasury Stock purchases			$ (2,621)					$ (2,621)
Treasury Stock purchases (in shares)			(98,126)					(98,126)
Class A Partnership Units and other equity purchased or converted into Class A Common Stock	$ 1	$ (1)		900			(117)	$ 783
Class A Partnership Units and other equity purchased or converted into Class A Common Stock (in shares)	103,538	(88,911)
Net excess tax benefit (detriment) from equity-based compensation				(48)				(48)
Other				766				766
Balance at end of the period at Sep. 30, 2016	$ 209	$ 311	$ (10,237)	256,531	(37,596)	(444)	53,750	262,524
Balance at end of the period (in shares) at Sep. 30, 2016	20,894,035	31,138,193	(361,748)
Changes in Equity
Cumulative Effect Adjustment upon Adoption of ASU 2016-09				4,855	(4,197)			658
Balance at beginning of the period, as adjusted	$ 210	$ 311	$ (10,930)	295,881	(72,426)	(543)	39,596	252,099
Balance at beginning of the period at Dec. 31, 2016	$ 210	$ 311	$ (10,930)	291,026	(68,229)	(543)	39,596	251,441
Balance at beginning of the period (in shares) at Dec. 31, 2016	20,948,998	31,138,193	(387,890)
Changes in Equity
Net income (loss)					54,213		77,961	132,174
Equity-based compensation	$ 16			71,228			1,668	72,912
Equity-based compensation (in shares)	1,602,236
Other comprehensive income (loss)						1,086	1,148	2,234
Dividends declared and distributions				20,911	(80,923)		(104,206)	(164,218)
Treasury Stock purchases			$ (9,832)					$ (9,832)
Treasury Stock purchases (in shares)			(264,710)					(264,710)
Exercise of stock options	$ 2			5,569				$ 5,571
Exercise of stock options (in shares)	256,270
Issuance of Class A common stock and cancellation of Class B common stock in connection with offerings and other exchanges	$ 111	$ (111)		57,035			(5,024)	52,011
Issuance of Class A common stock and cancellation of Class B common stock in connection with offerings and other exchanges (in shares)	11,092,457	(11,092,457)
Equity-based payments to non-employees				4,066				4,066
Other				55				55
Other (in shares)	(86)
Balance at end of the period at Sep. 30, 2017	$ 339	$ 200	$ (20,762)	$ 454,745	$ (99,136)	$ 543	$ 11,143	$ 347,072
Balance at end of the period (in shares) at Sep. 30, 2017	33,899,875	20,045,736	(652,600)