CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Other Cumulative Comprehensive Loss	Treasury Stock and Company Stock Held for Deferred Compensation
Balances (in shares) at Dec. 31, 2017		14,821,801				39,783
Balances at Dec. 31, 2017	$ 105,780	$ 741	$ 76,146	$ 60,074	$ (30,819)	$ (362)
Increase (Decrease) in Stockholders' Equity
Net income	10,292			10,292
Change in cumulative foreign currency translation adjustment	(2,751)				(2,751)
Shares issued in connection with stock compensation plans (in shares)		151,378
Shares issued in connection with stock compensation plans	232	$ 8	224
Stock-based compensation	1,719		1,719
Dividends declared	(595)			(595)
Treasury stock activity and transfers of stock to rabbi trust	(383)					$ (383)
Treasury stock purchases (in shares)						(33,669)
Balances (in shares) at Jun. 30, 2018		14,973,179				73,452
Balances at Jun. 30, 2018	114,229	$ 749	78,089	69,706	(33,570)	$ (745)
Balances (in shares) at Mar. 31, 2018		14,948,294				72,104
Balances at Mar. 31, 2018	111,357	$ 747	76,895	63,634	(29,214)	$ (705)
Increase (Decrease) in Stockholders' Equity
Net income	6,372			6,372
Change in cumulative foreign currency translation adjustment	(4,356)				(4,356)
Shares issued in connection with stock compensation plans (in shares)		24,885
Shares issued in connection with stock compensation plans	232	$ 2	230
Stock-based compensation	964		964
Dividends declared	(300)			(300)
Treasury stock activity and transfers of stock to rabbi trust	(40)					$ (40)
Treasury stock purchases (in shares)						(1,348)
Balances (in shares) at Jun. 30, 2018		14,973,179				73,452
Balances at Jun. 30, 2018	114,229	$ 749	78,089	69,706	(33,570)	$ (745)
Balances (in shares) at Dec. 31, 2018		14,987,962				82,186
Balances at Dec. 31, 2018	134,286	$ 749	80,077	89,291	(35,014)	$ (817)
Increase (Decrease) in Stockholders' Equity
Net income	32,414			32,414
Change in cumulative foreign currency translation adjustment	1,119				1,119
Shares issued in connection with stock compensation plans (in shares)		119,952				7,502
Shares issued in connection with stock compensation plans	358	$ 7	351
Stock-based compensation	2,411		2,411
Dividends declared	(598)			(598)
Treasury stock activity and transfers of stock to rabbi trust	(6,489)		14			$ (6,503)
Treasury stock purchases (in shares)						(386,139)
Balances (in shares) at Jun. 30, 2019		15,107,914				460,823
Balances at Jun. 30, 2019	163,501	$ 756	82,853	121,107	(33,895)	$ (7,320)
Balances (in shares) at Mar. 31, 2019		15,089,080				103,384
Balances at Mar. 31, 2019	148,911	$ 755	81,122	104,162	(35,433)	$ (1,695)
Increase (Decrease) in Stockholders' Equity
Net income	17,244			17,244
Change in cumulative foreign currency translation adjustment	1,538				1,538
Shares issued in connection with stock compensation plans (in shares)		18,834
Shares issued in connection with stock compensation plans	358	$ 1	357
Stock-based compensation	1,360		1,360
Dividends declared	(299)			(299)
Treasury stock activity and transfers of stock to rabbi trust	(5,611)		14			$ (5,625)
Treasury stock purchases (in shares)						(357,439)
Balances (in shares) at Jun. 30, 2019		15,107,914				460,823
Balances at Jun. 30, 2019	$ 163,501	$ 756	$ 82,853	$ 121,107	$ (33,895)	$ (7,320)