Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)	Non- controlling Interest
Beginning Balance at Dec. 31, 2018	$ 387,352		$ 95	$ 247,790	$ 144,364		$ (5,640)	$ 743
Comprehensive income:
Net income	42,606				42,346			260
Other comprehensive income (loss)	10,316						10,316
Stock-based compensation expense	3,643			3,643
Exercise of stock options, net	4,382		2	4,380
Issuance of common stock	449			449
Purchase and retirement of common stock	(19,731)		(3)	(19,728)
Distribution to noncontrolling interest	(275)							(275)
Ending Balance at Sep. 30, 2019	428,742		94	236,534	186,710		4,676	728
Beginning Balance at Jun. 30, 2019	412,148		94	234,963	173,180		3,178	733
Comprehensive income:
Net income	13,612				13,530			82
Other comprehensive income (loss)	1,498						1,498
Stock-based compensation expense	1,144			1,144
Exercise of stock options, net	1,200			1,200
Issuance of common stock	166			166
Purchase and retirement of common stock	(939)			(939)
Distribution to noncontrolling interest	(87)							(87)
Ending Balance at Sep. 30, 2019	428,742		94	236,534	186,710		4,676	728
Beginning Balance at Dec. 31, 2019	516,990	$ (6,175)	106	312,733	199,005	$ (6,175)	4,418	728
Comprehensive income:
Net income	42,384				42,135			249
Other comprehensive income (loss)	9,047						9,047
Stock-based compensation expense	4,216			4,216
Exercise of stock options, net	1,048			1,048
Issuance of common stock	482			482
Purchase and retirement of common stock	(28,947)		(4)	(28,943)
Distribution to noncontrolling interest	(176)							(176)
Ending Balance at Sep. 30, 2020	538,869		102	289,536	234,965		13,465	801
Beginning Balance at Jun. 30, 2020	532,853		104	301,778	216,863		13,288	820
Comprehensive income:
Net income	18,132				18,102			30
Other comprehensive income (loss)	177						177
Stock-based compensation expense	1,260			1,260
Exercise of stock options, net	94			94
Issuance of common stock	148			148
Purchase and retirement of common stock	(13,746)		(2)	(13,744)
Distribution to noncontrolling interest	(49)							(49)
Ending Balance at Sep. 30, 2020	$ 538,869		$ 102	$ 289,536	$ 234,965		$ 13,465	$ 801