Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	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	28,994			28,816		178
Other comprehensive income (loss)	8,818				8,818
Stock-based compensation expense	2,499		2,499
Exercise of stock options, net	3,182	2	3,180
Issuance of common stock	283		283
Purchase and retirement of common stock	(18,792)	(3)	(18,789)
Distribution to noncontrolling interest	(188)					(188)
Ending Balance at Jun. 30, 2019	412,148	94	234,963	173,180	3,178	733
Beginning Balance at Mar. 31, 2019	399,593	94	244,063	154,631	(21)	826
Comprehensive income:
Net income	18,644			18,549		95
Other comprehensive income (loss)	3,199				3,199
Stock-based compensation expense	1,391		1,391
Exercise of stock options, net	2,484	2	2,482
Issuance of common stock	135		135
Purchase and retirement of common stock	(13,110)	(2)	(13,108)
Distribution to noncontrolling interest	(188)					(188)
Ending Balance at Jun. 30, 2019	412,148	94	234,963	173,180	3,178	733
Beginning Balance at Dec. 31, 2019	516,990	106	312,733	199,005	4,418	728
Comprehensive income:
Net income	24,252			24,033		219
Other comprehensive income (loss)	8,870				8,870
Stock-based compensation expense	2,956		2,956
Exercise of stock options, net	954		954
Issuance of common stock	334		334
Purchase and retirement of common stock	(15,201)	(2)	(15,199)
Distribution to noncontrolling interest	(127)					(127)
Ending Balance at Jun. 30, 2020	532,853	104	301,778	216,863	13,288	820
Beginning Balance at Mar. 31, 2020	511,740	104	299,903	203,385	7,579	769
Comprehensive income:
Net income	13,579			13,478		101
Other comprehensive income (loss)	5,709				5,709
Stock-based compensation expense	1,657		1,657
Exercise of stock options, net	103		103
Issuance of common stock	119		119
Purchase and retirement of common stock	(4)		(4)
Distribution to noncontrolling interest	(50)					(50)
Ending Balance at Jun. 30, 2020	$ 532,853	$ 104	$ 301,778	$ 216,863	$ 13,288	$ 820