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)
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, 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)	107,111
Treasury Stock Purchases	$ (24,172)
Treasury Stock purchases (in shares)	(475,169)
Balance at end of the period at Jun. 30, 2018	$ 353,111	$ 422	$ 152	$ (47,360)	605,897	(182,256)	457	(24,201)
Balance at end of the period (in shares) at Jun. 30, 2018		42,176,435	15,178,575	(1,182,585)
Balance at beginning of the period at Mar. 31, 2018	300,177	$ 411	$ 152	$ (43,977)	566,015	(194,386)	1,738	(29,776)
Balance at beginning of the period (in shares) at Mar. 31, 2018		41,080,910	15,222,935	(1,121,743)
Changes in Equity
Net income (loss)	53,130					35,690		17,440
Equity-based compensation	26,091	$ 8			25,839			244
Equity-based compensation (in shares)		751,997
Other comprehensive income (loss)	(1,843)						(1,281)	(562)
Dividends declared and distributions	(30,116)				4,388	(23,560)		(10,944)
Treasury Stock Purchases	(3,383)			$ (3,383)
Treasury Stock purchases (in shares)				(60,842)
Exercise of Stock options	6,330	$ 3			6,327
Exercise of stock options (in shares)		325,286
Issuance of Class A common stock and cancellation of Class B common stock in connection with offerings and other exchanges	1,740				1,666			74
Issuance of Class A common stock and cancellation of Class B common stock in connection with offerings and other exchanges (in shares)		18,242	(18,242)
Equity-based payments to non-employees	1,662				1,662
Other	(677)							(677)
Other (in shares)			(26,118)
Balance at end of the period at Jun. 30, 2018	353,111	$ 422	$ 152	$ (47,360)	605,897	(182,256)	457	(24,201)
Balance at end of the period (in shares) at Jun. 30, 2018		42,176,435	15,178,575	(1,182,585)
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)
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)
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)	53,844
Treasury Stock Purchases	$ (39,610)
Treasury Stock purchases (in shares)	(971,835)
Balance at end of the period at Jun. 30, 2019	$ 312,858	$ 516	$ 104	$ (96,271)	791,403	(327,353)	667	(56,208)
Balance at end of the period (in shares) at Jun. 30, 2019		51,629,289	10,431,422	(2,397,950)
Balance at beginning of the period at Mar. 31, 2019	287,143	$ 494	$ 105	$ (83,631)	756,349	(327,648)	712	(59,238)
Balance at beginning of the period (in shares) at Mar. 31, 2019		49,457,698	10,493,358	(2,042,911)
Changes in Equity
Net income (loss)	37,667					29,459		8,208
Equity-based compensation	28,246	$ 18			28,187			41
Equity-based compensation (in shares)		1,787,993
Other comprehensive income (loss)	(57)						(45)	(12)
Dividends declared and distributions	(31,146)				4,514	(29,164)		(6,496)
Treasury Stock Purchases	(12,308)			$ (12,308)
Treasury Stock purchases (in shares)				(344,970)
Exercise of Stock options	5,043	$ 3		$ (332)	5,372
Exercise of stock options (in shares)		321,662		(10,069)
Issuance of Class A common stock and cancellation of Class B common stock in connection with offerings and other exchanges	430	$ 1	$ (1)		(1,580)			2,010
Issuance of Class A common stock and cancellation of Class B common stock in connection with offerings and other exchanges (in shares)		61,936	(61,936)
Equity-based payments to non-employees	111				111
Other	(2,271)				(1,550)			(721)
Balance at end of the period at Jun. 30, 2019	$ 312,858	$ 516	$ 104	$ (96,271)	$ 791,403	$ (327,353)	$ 667	$ (56,208)
Balance at end of the period (in shares) at Jun. 30, 2019		51,629,289	10,431,422	(2,397,950)