CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non Controlling Interest	Total
Balance at Dec. 31, 2018	$ 5	$ 144,048	$ 461,075	$ (908)	$ 2,763	$ 606,983
Balance (in shares) at Dec. 31, 2018	50,715,518
Increase (Decrease) in Stockholders' Equity Roll Forward
Net income			55,382		1,204	56,586
Foreign currency translation adjustments, net of tax				570		570
Issuance of shares to employees and/or directors		2,998				2,998
Issuance of shares to employees and/or directors (in shares)	144,261
Conversion of Restricted Stock Units, net of shares withheld for taxes		(1,519)				$ (1,519)
Conversion of Restricted Stock Units, net of shares withheld for taxes (in shares)	122,319					122,319
Amortization of Restricted Stock Units		1,218				$ 1,218
Dividend equivalent Units accrued - Restricted Stock Units		20	(20)
Distribution of noncontrolling entities					(3,505)	(3,505)
Dividends declared			(9,168)			(9,168)
Balance at Sep. 30, 2019	$ 5	146,765	507,269	(338)	462	654,163
Balance (in shares) at Sep. 30, 2019	50,982,098
Balance at Jun. 30, 2019	$ 5	146,064	474,684	(172)	284	620,865
Balance (in shares) at Jun. 30, 2019	50,965,221
Increase (Decrease) in Stockholders' Equity Roll Forward
Net income			35,648		178	35,826
Foreign currency translation adjustments, net of tax				(166)		(166)
Issuance of shares to employees and/or directors		337				337
Issuance of shares to employees and/or directors (in shares)	16,877
Amortization of Restricted Stock Units		360				360
Dividend equivalent Units accrued - Restricted Stock Units		4	(4)
Dividends declared			(3,059)			(3,059)
Balance at Sep. 30, 2019	$ 5	146,765	507,269	(338)	462	654,163
Balance (in shares) at Sep. 30, 2019	50,982,098
Balance at Dec. 31, 2019	$ 5	97,130	531,291	76	1,028	629,530
Balance (in shares) at Dec. 31, 2019	48,665,138
Increase (Decrease) in Stockholders' Equity Roll Forward
Net income			73,163		8	73,171
Foreign currency translation adjustments, net of tax				(727)		(727)
Issuance of shares to employees and/or directors		1,494				1,494
Issuance of shares to employees and/or directors (in shares)	70,805
Conversion of Restricted Stock Units, net of shares withheld for taxes		(548)				(548)
Conversion of Restricted Stock Units, net of shares withheld for taxes (in shares)	54,635
Amortization of Restricted Stock Units		1,730				1,730
Dividend equivalent Units accrued - Restricted Stock Units		10	(10)
Repurchase of stock		(11,453)				(11,453)
Repurchase of stock (in shares)	(694,260)
Distribution of noncontrolling entities					(1,000)	(1,000)
Dividends declared			(8,675)			(8,675)
Balance at Sep. 30, 2020	$ 5	88,363	595,769	(651)	36	683,522
Balance (in shares) at Sep. 30, 2020	48,096,318
Balance at Jun. 30, 2020	$ 5	91,257	554,717	(1,109)	34	644,904
Balance (in shares) at Jun. 30, 2020	48,220,811
Increase (Decrease) in Stockholders' Equity Roll Forward
Net income			43,941		2	43,943
Foreign currency translation adjustments, net of tax				458		458
Issuance of shares to employees and/or directors		157				157
Issuance of shares to employees and/or directors (in shares)	9,086
Conversion of Restricted Stock Units, net of shares withheld for taxes		(471)				$ (471)
Conversion of Restricted Stock Units, net of shares withheld for taxes (in shares)	41,119					54,635
Amortization of Restricted Stock Units		528				$ 528
Dividend equivalent Units accrued - Restricted Stock Units		2	(2)
Repurchase of stock		(3,110)				(3,110)
Repurchase of stock (in shares)	(174,698)
Dividends declared			(2,887)			(2,887)
Balance at Sep. 30, 2020	$ 5	$ 88,363	$ 595,769	$ (651)	$ 36	$ 683,522
Balance (in shares) at Sep. 30, 2020	48,096,318