Restatement and Revision of Prior Period Quarterly Financial Statements - Condensed Consolidated Statement of Income (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Changes and Error Corrections [Abstract]
Revenue	$ 305,367	$ 288,523	$ 280,066	$ 264,405	$ 275,727	$ 276,002	$ 272,212	$ 270,461	$ 544,471	$ 542,673	$ 832,994	$ 818,675	$ 1,138,361	$ 1,094,402	$ 1,028,892
Cost of Goods Sold		216,602	210,020	199,701		209,421	206,232	208,935	409,721	415,167	626,323	624,588	862,903	831,838	788,862
Gross profit	68,787	71,921	70,046	64,704	68,477	66,581	65,980	61,526	134,750	127,506	206,671	194,087	275,458	262,564	240,030
Selling, general and administrative		57,186	55,054	53,615		52,466	51,622	51,477	108,669	103,099	165,855	155,565	227,253	209,524	197,247
Depreciation and amortization		3,317	3,182	2,904		5,066	4,720	4,596	6,086	9,316	9,403	14,382	13,390	17,916	17,472
Change in fair value of contingent consideration liability		(167)	1,884	(1,040)		788	7,276	1,911	844	9,187	677	9,975	677	10,417	(270)
Goodwill impairment charge													0	0	37,539
Intangible asset impairment charges									0	789			0	70	202
Restructuring charges		0	0	0		465	623	3,344	0	3,967	0	4,433	0	5,615	1,053
Income (loss) from operations		11,585	9,926	9,225		7,796	1,739	198	19,151	1,937	30,736	9,732	34,138	19,022	(13,213)
Interest income		31	12	34		26	24	14	46	38	77	63	97	86	69
Interest expense		(1,198)	(1,038)	(1,003)		(1,190)	(985)	(1,077)	(2,041)	(2,062)	(3,239)	(3,252)	(4,729)	(4,171)	(4,612)
Other, net		426	(1,164)	(224)		(114)	291	(161)	(1,388)	130	(962)	16	(1,788)	(154)	(3,135)
Total other expense		(741)	(2,190)	(1,193)		(1,279)	(670)	(1,224)	(3,383)	(1,894)	(4,124)	(3,173)	(6,420)	(4,239)	(7,678)
Income (loss) before taxes		10,844	7,736	8,032		6,517	1,069	(1,026)	15,768	42	26,612	6,559	27,718	14,783	(20,891)
Income tax expense (benefit)		3,728	3,362	2,354		2,292	2,974	2,110	5,716	5,084	9,444	7,376	11,288	10,834	11,498
Net income (loss)	$ (738)	$ 7,116	$ 4,374	$ 5,678	$ 4,765	$ 4,225	$ (1,905)	$ (3,136)	$ 10,052	$ (5,043)	$ 17,168	$ (817)	$ 16,430	$ 3,949	$ (32,389)
Basic earnings (loss) per share (in USD per share)	$ (0.01)	$ 0.13	$ 0.08	$ 0.11	$ 0.09	$ 0.08	$ (0.04)	$ (0.06)	$ 0.19	$ (0.09)	$ 0.32	$ (0.02)	$ 0.31	$ 0.07	$ (0.61)
Diluted earnings (loss) per share (in USD per share)	$ (0.01)	$ 0.13	$ 0.08	$ 0.10	$ 0.09	$ 0.08	$ (0.04)	$ (0.06)	$ 0.18	$ (0.09)	$ 0.31	$ (0.02)	$ 0.30	$ 0.07	$ (0.61)
Comprehensive income (loss)		$ 9,284	$ 8,253	$ 7,657		$ 4,024	$ (3,295)	$ (3,411)	$ 15,911	$ (6,708)	$ 25,196	$ (2,683)	$ 18,150	$ (3,198)	$ (40,640)