Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013 item	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Information
Number of reportable segments									3
Segment Information
Net sales	$ 160,322	$ 195,877	$ 195,596	$ 154,535	$ 144,686	$ 172,113	$ 181,703	$ 158,734	$ 706,329	$ 657,236	$ 603,446
Income (loss) from operations	11,903	30,885	29,678	9,013	(937)	21,990	27,148	13,508	81,478	61,709	74,057
Depreciation and amortization									27,518	26,857	20,751
Impairment of Goodwill					2,346					2,346	1,282
Impairment of long-lived asset									1,025	803	1,094
Significant non-cash charges									12,747	10,667	6,837
Provision for (benefit from) income taxes	4,289	10,870	11,177	4,256	(6,785)	9,069	11,347	6,372	30,593	20,003	27,886
Capital expenditures and asset acquisitions, net of cash acquired									23,297	87,086	77,916
Total assets	953,613				890,322				953,613	890,322	836,087
Cash and short-term investments	251,208				175,553				251,208	175,553	213,817	335,049
Administrative and all other
Segment Information
Lease term of entity's facilities in Vacaville									10 years
Net sales									948	949	950
Income (loss) from operations									(2,463)	1,017	(1,118)
Depreciation and amortization									1,293	1,466	1,497
Significant non-cash charges									2,177	2,051	1,278
Provision for (benefit from) income taxes									1,416	1,099	755
Capital expenditures and asset acquisitions, net of cash acquired									9		19
Total assets	93,473				82,366				93,473	82,366	86,683
Cash and short-term investments	156,000				91,900				156,000	91,900	68,500
Intersegment elimination
Segment Information
Net sales									21,421	21,272	16,739
North America
Segment Information
Net sales									572,789	522,895	474,722
Income (loss) from operations									84,885	71,586	75,350
Depreciation and amortization									17,707	16,317	13,194
Impairment of long-lived asset										461	1,094
Significant non-cash charges									8,867	7,369	4,464
Provision for (benefit from) income taxes									26,372	15,037	25,348
Capital expenditures and asset acquisitions, net of cash acquired									19,424	23,014	72,291
Total assets	627,196				583,501				627,196	583,501	540,082
North America | Intersegment elimination
Segment Information
Net sales									4,735	5,121	4,805
Europe
Segment Information
Net sales									117,799	122,549	118,246
Income (loss) from operations									1,258	(8,095)	1,296
Depreciation and amortization									7,019	7,744	4,849
Impairment of Goodwill										2,346	1,282
Impairment of long-lived asset									1,025	342
Significant non-cash charges									1,561	1,053	966
Provision for (benefit from) income taxes									2,906	3,544	2,588
Capital expenditures and asset acquisitions, net of cash acquired									2,244	63,156	5,062
Total assets	201,384				194,000				201,384	194,000	180,016
Europe | Intersegment elimination
Segment Information
Net sales									352	430	575
Asia/Pacific
Segment Information
Net sales									14,793	10,843	9,528
Income (loss) from operations									(2,202)	(2,799)	(1,471)
Depreciation and amortization									1,499	1,330	1,211
Significant non-cash charges									142	194	129
Provision for (benefit from) income taxes									(101)	323	(805)
Capital expenditures and asset acquisitions, net of cash acquired									1,620	916	544
Total assets	31,560				30,455				31,560	30,455	29,306
Asia/Pacific | Intersegment elimination
Segment Information
Net sales									16,334	15,721	11,359
Foreign operating entities
Segment Information
Cash and short-term investments	$ 96,400								$ 96,400
Percentage of cash and cash equivalents	38.40%								38.40%