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	15,202			15,202
Change in cumulative foreign currency translation adjustment	(2,987)				(2,987)
Shares issued in connection with stock compensation plans (in shares)		156,378
Shares issued in connection with stock compensation plans	232	$ 8	224
Stock-based compensation	2,574		2,574
Dividends declared	(893)			(893)
Treasury stock activity and transfers of stock to rabbi trust	(453)					$ (453)
Treasury stock activity and transfers of stock to rabbit trust (in shares)						(42,353)
Balances (in shares) at Sep. 30, 2018		14,978,179				82,136
Balances at Sep. 30, 2018	119,390	$ 749	78,944	74,318	(33,806)	$ (815)
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)
Increase (Decrease) in Stockholders' Equity
Net income	4,910			4,910
Change in cumulative foreign currency translation adjustment	(236)				(236)
Shares issued in connection with stock compensation plans (in shares)		5,000
Shares issued in connection with stock compensation plans	0
Stock-based compensation	855		855
Dividends declared	(298)			(298)
Treasury stock activity and transfers of stock to rabbi trust	(70)					$ (70)
Treasury stock activity and transfers of stock to rabbit trust (in shares)						(8,684)
Balances (in shares) at Sep. 30, 2018		14,978,179				82,136
Balances at Sep. 30, 2018	119,390	$ 749	78,944	74,318	(33,806)	$ (815)
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	39,329			39,329
Change in cumulative foreign currency translation adjustment	(1,577)				(1,577)
Shares issued in connection with stock compensation plans (in shares)		121,702				7,502
Shares issued in connection with stock compensation plans	358	$ 7	351
Stock-based compensation	3,756		3,756
Dividends declared	(2,464)			(2,464)
Treasury stock activity and transfers of stock to rabbi trust	(6,612)		14			$ (6,626)
Treasury stock activity and transfers of stock to rabbit trust (in shares)						(389,645)
Balances (in shares) at Sep. 30, 2019		15,109,664				464,329
Balances at Sep. 30, 2019	167,076	$ 756	84,198	126,156	(36,591)	$ (7,443)
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)
Increase (Decrease) in Stockholders' Equity
Net income	6,915			6,915
Change in cumulative foreign currency translation adjustment	(2,696)				(2,696)
Shares issued in connection with stock compensation plans (in shares)		1,750
Shares issued in connection with stock compensation plans	0
Stock-based compensation	1,345		1,345
Dividends declared	(1,866)			(1,866)
Treasury stock activity and transfers of stock to rabbi trust	(123)					$ (123)
Treasury stock activity and transfers of stock to rabbit trust (in shares)						(3,506)
Balances (in shares) at Sep. 30, 2019		15,109,664				464,329
Balances at Sep. 30, 2019	$ 167,076	$ 756	$ 84,198	$ 126,156	$ (36,591)	$ (7,443)