Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Current assets:
Cash and cash equivalents	$ 28,739	$ 20,073	$ 22,310	$ 30,628	$ 29,289	$ 30,988	$ 29,791	$ 33,063	$ 39,829	$ 29,582
Trade and other accounts receivable, net of allowance for doubtful accounts of $157 and $450 at December 31, 2012 and 2011, respectively	33,420	38,816	34,334	32,523	27,973	30,007	32,201	26,214
Inventories	41,620	43,802	41,039	39,180	33,234	29,662	29,030	26,465
Prepaid expenses and other current assets	3,228	2,975	3,458	3,295	3,152	3,204	2,955	2,683
Total current assets	107,007	105,666	101,141	105,626	93,648	93,861	93,977	88,425
Property and equipment, net	36,235	35,806	33,275	31,922	28,541	26,985	24,952	22,257
Intangible assets, net	669	758	854	985	1,111	1,259	1,438	1,526
Goodwill	25,416	24,826	24,621	25,730	24,887	25,592	27,423	25,338	24,956
Pension asset	6,939	6,945	6,685	6,815	6,359	6,125	6,387	5,642
Other non-current assets	206	38	38	0	200	246	382	471
Total assets	176,472	174,039	166,614	171,078	154,746	154,068	154,559	143,659
Current liabilities:
Accounts payable and accrued liabilities	27,181	31,989	31,245	34,254	36,100	30,971	30,628	28,851
Accrued warranty	269	244	265	287	258	261	304	367
Accrued employee compensation	4,743	5,025	5,721	5,850	6,343	7,037	6,931	4,942
Deferred revenue	6,408	5,149	4,170	2,568	1,042
Short-term borrowings and current portion of long-term debt	9,452	9,844	10,224	10,649	5,431	3,409	3,685	3,470
Deferred tax liability	980	499	499	499	499	1,373	1,373	1,373
Total current liabilities	49,033	52,750	52,124	54,107	49,673	45,529	44,097	39,422
Deferred tax liability, long-term	1,384	962	952	944	933	1,166	1,166	1,166
Long-term debt, excluding current portion	83	25	35	47	68	2,292	2,504	2,282
Other long-term liabilities	1,039	699	750	778	3,028	3,028	3,070	3,049
Total liabilities	51,539	54,436	53,861	55,876	53,702	52,015	50,837	45,919
Commitments and contingencies (Note 12 and Note 14)
Stockholders’ equity:
Common stock, $0.10 par value per share, 40,000 shares authorized; 29,162 and 28,174 shares issued and outstanding at December 31, 2012 and 2011, respectively	2,913	2,915	2,911	2,910	2,815	2,797	2,780	2,779
Additional paid-in capital	267,623	267,069	266,225	265,414	252,907	252,525	250,341	249,558
Accumulated deficit	(158,134)	(161,000)	(166,229)	(166,260)	(165,308)	(165,823)	(166,392)	(166,192)
Accumulated other comprehensive income	12,531	10,619	9,846	13,138	10,630	12,554	16,993	11,595
Total stockholders’ equity	124,933	119,603	112,753	115,202	101,044	102,053	103,722	97,740	88,023	77,992
Total liabilities and stockholders’ equity	$ 176,472	$ 174,039	$ 166,614	$ 171,078	$ 154,746	$ 154,068	$ 154,559	$ 143,659