CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Non-controlling Interest	Class A Common Stock Common stock	Class B Common Stock Common stock
Balance at the beginning of the period (in shares) at Dec. 31, 2018						37,654	37,236
Balance at the beginning of the period at Dec. 31, 2018	$ 362,328	$ 126,418	$ 51,683	$ (820)	$ 184,670	$ 377	$ 0
Statement of Stockholders'/Members' Equity
Adjustment to prior periods	(506)	12,569		488	(13,563)
Member distributions	(5,853)				(5,853)
Effect of CW Unit redemptions (in shares)						9,221	(9,221)
Effect of CW Unit redemptions		48,344		(57)	(48,379)	$ 92
Adjustment to deferred tax asset from CW Unit redemptions	(9,751)	(9,751)
Tax impact of equity transactions	14,652	14,652
Equity award vestings (in shares)						225
Equity award vestings	(1,527)	(4,080)			2,551	$ 2
Other comprehensive loss	(570)			(403)	(167)
Stock-based compensation	5,257	5,257
Net income	125,029		67,554		57,475
Balance at the end of the period (in shares) at Sep. 30, 2019						47,100	28,015
Balance at the end of the period at Sep. 30, 2019	489,059	193,409	119,237	(792)	176,734	$ 471	$ 0
Balance at the beginning of the period (in shares) at Jun. 30, 2019						47,093	28,020
Balance at the beginning of the period at Jun. 30, 2019	454,530	193,160	99,898	(498)	161,499	$ 471	$ 0
Statement of Stockholders'/Members' Equity
Adjustment to prior periods	(506)	(1,466)			960
Member distributions	(2,005)				(2,005)
Effect of CW Unit redemptions (in shares)						5	(5)
Effect of CW Unit redemptions		39		0	(39)	$ 0
Equity award vestings (in shares)						2
Equity award vestings	(13)	(13)			0
Other comprehensive loss	(469)			(294)	(175)
Stock-based compensation	1,689	1,689
Net income	35,833		19,339		16,494
Balance at the end of the period (in shares) at Sep. 30, 2019						47,100	28,015
Balance at the end of the period at Sep. 30, 2019	489,059	193,409	119,237	(792)	176,734	$ 471	$ 0
Balance at the beginning of the period (in shares) at Dec. 31, 2019						47,159	27,958
Balance at the beginning of the period at Dec. 31, 2019	516,395	194,456	132,990	(452)	188,929	$ 472	$ 0
Statement of Stockholders'/Members' Equity
Member distributions	(15,560)				(15,560)
Effect of CW Unit redemptions (in shares)						142	(142)
Effect of CW Unit redemptions		1,015		0	(1,016)	$ 1
Tax impact of equity transactions	261	261
Equity award vestings (in shares)						246
Equity award vestings	(1,386)	(214)			(1,174)	$ 2
Other comprehensive loss	329			186	143
Stock-based compensation	6,436	4,052			2,384
Cash dividends declared on Class A common Stock	(12,994)		(12,994)
Net income	53,079		31,244		21,835
Balance at the end of the period (in shares) at Sep. 30, 2020						47,547	27,816
Balance at the end of the period at Sep. 30, 2020	546,560	199,570	151,240	(266)	195,541	$ 475	$ 0
Balance at the beginning of the period (in shares) at Jun. 30, 2020						47,478	27,884
Balance at the beginning of the period at Jun. 30, 2020	547,907	197,484	149,356	(569)	201,161	$ 475	$ 0
Statement of Stockholders'/Members' Equity
Member distributions	(10,848)				(10,848)
Effect of CW Unit redemptions (in shares)						68	(68)
Effect of CW Unit redemptions		476			(476)	$ 0
Tax impact of equity transactions	199	199
Equity award vestings (in shares)						1
Equity award vestings	0	4			(4)
Other comprehensive loss	533			303	230
Stock-based compensation	2,232	1,407			825
Cash dividends declared on Class A common Stock	(4,349)		(4,349)
Net income	10,886		6,233		4,653
Balance at the end of the period (in shares) at Sep. 30, 2020						47,547	27,816
Balance at the end of the period at Sep. 30, 2020	$ 546,560	$ 199,570	$ 151,240	$ (266)	$ 195,541	$ 475	$ 0