Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	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
Balance at beginning of the period at Dec. 31, 2017	$ 344,256	$ 342	$ 199	$ (23,188)	$ 487,163	$ (139,918)	$ 352	$ 19,306
Balance at beginning of the period (in shares) at Dec. 31, 2017		34,163,042	19,912,230	(707,416)
Cumulative Effect Adjustment upon Adoption of ASU (ASU 2014-09) at Dec. 31, 2017	3,155					3,155
Cumulative Effect Adjustment upon Adoption of ASU (ASU 2016-01) at Dec. 31, 2017						(317)	317
Balance at beginning of the period, as adjusted at Dec. 31, 2017	347,411	$ 342	$ 199	$ (23,188)	487,163	(137,080)	669	19,306
Changes in Equity
Net income (loss)	53,981					33,325		20,656
Equity-based compensation	32,244	$ 22			31,764			458
Equity-based compensation (in shares)		2,210,079
Other comprehensive income (loss)	1,679						1,069	610
Dividends declared and distributions	(137,029)				20,379	(90,631)		(66,777)
Treasury Stock Purchases	$ (20,789)			$ (20,789)
Treasury Stock purchases (in shares)	(414,327)			(414,327)
Exercise of Stock options	$ 365				365
Exercise of stock options (in shares)		18,494
Issuance of Class A common stock and cancellation of Class B common stock in connection with offerings and other exchanges	20,299	$ 47	$ (47)		24,328			(4,029)
Issuance of Class A common stock and cancellation of Class B common stock in connection with offerings and other exchanges (in shares)		4,689,295	(4,689,295)
Equity-based payments to non-employees	2,016				2,016
Balance at end of the period at Mar. 31, 2018	300,177	$ 411	$ 152	$ (43,977)	566,015	(194,386)	1,738	(29,776)
Balance at end of the period (in shares) at Mar. 31, 2018		41,080,910	15,222,935	(1,121,743)
Balance at beginning of the period at Dec. 31, 2018	371,753	$ 470	$ 105	$ (56,661)	697,938	(237,782)	291	(32,608)
Balance at beginning of the period (in shares) at Dec. 31, 2018		47,031,095	10,493,358	(1,426,115)
Changes in Equity
Net income (loss)	16,177					13,570		2,607
Equity-based compensation	38,886	$ 24			38,753			109
Equity-based compensation (in shares)		2,397,164
Other comprehensive income (loss)	540						421	119
Dividends declared and distributions	(114,391)				19,484	(103,436)		(30,439)
Treasury Stock Purchases	$ (26,970)			$ (26,970)
Treasury Stock purchases (in shares)	(616,796)			(616,796)
Exercise of Stock options	$ 492				492
Exercise of stock options (in shares)		29,439
Equity-based payments to non-employees	416				416
Other	240				(734)			974
Balance at end of the period at Mar. 31, 2019	$ 287,143	$ 494	$ 105	$ (83,631)	$ 756,349	$ (327,648)	$ 712	$ (59,238)
Balance at end of the period (in shares) at Mar. 31, 2019		49,457,698	10,493,358	(2,042,911)