CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY Statement - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Other Comprehensive Income	Retained Earnings	Noncontrolling Interests
Balance, Stockholders Equity at Dec. 31, 2019	$ 641,513	$ 37	$ 645,256	$ (251,241)	$ 15	$ 246,383	$ 1,063
Balance (in shares) at Dec. 31, 2019		36,638,021
Issuance of stock - employee stock purchase plan	860		860
Issuance of stock - employee stock purchase plan (shares)		6,063
Issuance of stock - 401(k) plan	3,057		3,057
Issuance of stock - 401(k) plan (shares)		18,312
Issuance/(cancellation) of non-vested stock	0	$ 0	0
Issuance/(cancellation) of non-vested stock (shares)		55,423
Exercise of stock options	1,184		1,184
Exercise of stock options (in shares)		28,735
Non-cash compensation	5,909		5,909
Surrendered Shares	(4,050)			(4,050)
Noncontrolling interest distribution	(360)						(360)
Write-off of other comprehensive income	(15)				(15)
Net income	32,046					31,802	244
Balance, Stockholders Equity at Mar. 31, 2020	680,144	$ 37	656,266	(255,291)	0	278,185	947
Balance (in shares) at Mar. 31, 2020		36,746,554
Balance, Stockholders Equity at Dec. 31, 2020	810,741	$ 38	698,287	(319,092)	0	429,991	1,517
Balance (in shares) at Dec. 31, 2020		37,470,212
Issuance of stock - employee stock purchase plan	1,048		1,048
Issuance of stock - employee stock purchase plan (shares)		4,202
Issuance/(cancellation) of non-vested stock	0	$ 0	0
Issuance/(cancellation) of non-vested stock (shares)		57,001
Exercise of stock options	364		364
Exercise of stock options (in shares)		7,422
Non-cash compensation	7,307		7,307
Surrendered Shares	(6,774)		0	(6,774)
Shares repurchased	(72,886)			(72,886)
Noncontrolling interest distribution	(518)						(518)
Net income	50,292					49,870	422
Balance, Stockholders Equity at Mar. 31, 2021	$ 789,574	$ 38	$ 707,006	$ (398,752)	$ 0	$ 479,861	$ 1,421
Balance (in shares) at Mar. 31, 2021		37,538,837