CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (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, 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	0	1,015			(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 (income)	329			186	143
Stock-based compensation	6,436	4,052			2,384
Cash dividends declared	(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	0	476			(476)
Tax impact of equity transactions	199	199
Equity award vestings (in shares)						1
Equity award vestings	0	4			(4)
Other comprehensive loss (income)	533			303	230
Stock-based compensation	2,232	1,407			825
Cash dividends declared	(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
Balance at the beginning of the period (in shares) at Dec. 31, 2020						47,713	27,655
Balance at the beginning of the period at Dec. 31, 2020	550,770	202,077	150,086	330	197,800	$ 477	$ 0
Statement of Stockholders'/Members' Equity
Member distributions	(8,074)				(8,074)
Effect of CW Unit redemptions (in shares)						10,898	(10,898)
Effect of CW Unit redemptions	0	78,654			(78,763)	$ 109
Tax impact of equity transactions	2,628	2,628
Equity award vestings (in shares)						336
Equity award vestings	(3,192)	(1,079)			(2,116)	$ 3
Other comprehensive loss (income)	(804)			(495)	(309)
Stock-based compensation	6,546	4,773			1,773
Cash dividends declared	(15,261)		(15,261)
Net income	47,087		34,569		12,518
Balance at the end of the period (in shares) at Sep. 30, 2021						58,947	16,757
Balance at the end of the period at Sep. 30, 2021	579,700	287,053	169,394	(165)	122,829	$ 589	$ 0
Balance at the beginning of the period (in shares) at Jun. 30, 2021						58,038	17,665
Balance at the beginning of the period at Jun. 30, 2021	571,175	278,505	162,668	217	129,205	$ 580	$ 0
Statement of Stockholders'/Members' Equity
Member distributions	(4,514)				(4,514)
Effect of CW Unit redemptions (in shares)						908	(908)
Effect of CW Unit redemptions	0	6,743			(6,752)	$ 9
Tax impact of equity transactions	192	192
Equity award vestings (in shares)						1
Equity award vestings	(18)	(12)			(6)
Other comprehensive loss (income)	(529)			(382)	(147)
Stock-based compensation	2,108	1,625			483
Cash dividends declared	(5,891)		(5,891)
Net income	17,177		12,617		4,560
Balance at the end of the period (in shares) at Sep. 30, 2021						58,947	16,757
Balance at the end of the period at Sep. 30, 2021	$ 579,700	$ 287,053	$ 169,394	$ (165)	$ 122,829	$ 589	$ 0