Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock Outstanding [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2019	23,111,000
Balance at Dec. 31, 2019	$ 23	$ 386,534	$ (113,862)	$ (118,712)	$ (889)	$ 153,094
Net loss	0	0	0	(5,434)	0	(5,434)
Change in accumulated other comprehensive income (loss)	$ 0	0	0	0	201	201
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan (in shares)	211,000
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan		0	2,116	(49)	0	2,067
Issuance of treasury stock upon exercise of stock options, stock appreciation rights and vesting of restricted stock units by employees and directors (in shares)	578,000
Issuance of treasury stock upon exercise of stock options, stock appreciation rights and vesting of restricted stock units by employees and directors	$ 1	88	5,812	(4,424)	0	1,477
Equity-based compensation	$ 0	6,546	0	0	0	$ 6,546
Purchase of treasury stock (in shares)	(305,000)					(304,704)
Purchase of treasury stock		0	(3,736)	0	0	$ (3,736)
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan (in shares)	211,000
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan		0	2,116	(49)	0	2,067
Balance (in shares) at Sep. 30, 2020	23,595,000
Balance at Sep. 30, 2020	$ 24	393,168	(109,670)	(128,619)	(688)	154,215
Balance (in shares) at Jun. 30, 2020	23,410,000
Balance at Jun. 30, 2020	$ 23	390,734	(111,532)	(125,909)	(554)	152,762
Net loss	0	0	0	(1,891)	0	(1,891)
Change in accumulated other comprehensive income (loss)	$ 0	0	0	0	(134)	(134)
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan (in shares)	106,000
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan		1	1,063	(20)	0	1,044
Issuance of treasury stock upon exercise of stock options, stock appreciation rights and vesting of restricted stock units by employees and directors (in shares)	79,000
Issuance of treasury stock upon exercise of stock options, stock appreciation rights and vesting of restricted stock units by employees and directors	$ 1	0	799	(799)	0	1
Equity-based compensation	$ 0	2,433	0	0	0	2,433
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan (in shares)	106,000
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan		1	1,063	(20)	0	1,044
Balance (in shares) at Sep. 30, 2020	23,595,000
Balance at Sep. 30, 2020	$ 24	393,168	(109,670)	(128,619)	(688)	154,215
Balance (in shares) at Dec. 31, 2020	23,710,000
Balance at Dec. 31, 2020	$ 24	396,335	(108,509)	(130,975)	(637)	156,238
Net loss	0	0	0	(1,773)	0	(1,773)
Change in accumulated other comprehensive income (loss)	$ 0	0	0	0	(434)	(434)
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan (in shares)	183,000
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan		201	1,856	(3)	0	2,054
Issuance of treasury stock upon exercise of stock options, stock appreciation rights and vesting of restricted stock units by employees and directors (in shares)	656,000
Issuance of treasury stock upon exercise of stock options, stock appreciation rights and vesting of restricted stock units by employees and directors		58	6,642	(5,847)	0	853
Equity-based compensation	$ 0	8,212	0	0	0	$ 8,212
Purchase of treasury stock (in shares)	(367,000)					(367,238)
Purchase of treasury stock		0	(5,716)	0	0	$ (5,716)
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan (in shares)	183,000
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan		201	1,856	(3)	0	2,054
Balance (in shares) at Sep. 30, 2021	24,182,000
Balance at Sep. 30, 2021	$ 24	404,806	(105,727)	(138,598)	(1,071)	159,434
Balance (in shares) at Jun. 30, 2021	23,975,000
Balance at Jun. 30, 2021	$ 24	401,921	(107,717)	(137,129)	(970)	156,129
Net loss	0	0	0	(31)	0	(31)
Change in accumulated other comprehensive income (loss)	$ 0	0	0	0	(101)	(101)
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan (in shares)	87,000
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan		201	896	0	0	1,097
Issuance of treasury stock upon exercise of stock options, stock appreciation rights and vesting of restricted stock units by employees and directors (in shares)	148,000
Issuance of treasury stock upon exercise of stock options, stock appreciation rights and vesting of restricted stock units by employees and directors		7	1,510	(1,438)	0	79
Equity-based compensation	$ 0	2,677	0	0	0	2,677
Purchase of treasury stock (in shares)	(28,000)
Purchase of treasury stock		0	(416)	0	0	(416)
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan (in shares)	87,000
Issuance of treasury stock upon purchase of common stock under employee stock purchase plan		201	896	0	0	1,097
Balance (in shares) at Sep. 30, 2021	24,182,000
Balance at Sep. 30, 2021	$ 24	$ 404,806	$ (105,727)	$ (138,598)	$ (1,071)	$ 159,434