CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net sales	$ 604,973	$ 529,230	$ 1,141,270	$ 1,008,687
Cost of goods sold	435,876	379,698	817,733	719,244
Gross profit	169,097	149,532	323,537	289,443
Operating expenses:
Selling, general and administrative	125,785	113,602	247,212	226,664
Depreciation and amortization	20,341	19,027	40,227	37,423
Total operating expenses	146,126	132,629	287,439	264,087
Income from operations	22,971	16,903	36,098	25,356
Interest expense	(15,345)	(14,876)	(30,477)	(30,125)
Other income, net	57	95	124	13,384
Income before income taxes	7,683	2,122	5,745	8,615
Income tax expense	2,283	862	1,398	3,426
Net income	$ 5,400	$ 1,260	$ 4,347	$ 5,189
Earnings per share data:
Basic (in dollars per share)	$ 0.13	$ 0.03	$ 0.10	$ 0.13
Diluted (in dollars per share)	$ 0.13	$ 0.03	$ 0.10	$ 0.13
Weighted average shares outstanding:
Basic (in shares)	42,893,498	42,865,407	42,886,867	40,084,730
Diluted (in shares)	42,910,017	42,879,319	42,903,788	40,084,940
Comprehensive income:
Foreign currency translation adjustment	$ (1,831)	$ 2,085	$ (4,202)	$ 2,658
Unrealized gain (loss) on derivative, net of taxes of $0.4 million and $0.6 million, respectively and $1.0 million and $0.9 million, respectively	1,096	(939)	2,259	(1,400)
Total other comprehensive (loss) income	(735)	1,146	(1,943)	1,258
Total comprehensive income	$ 4,665	$ 2,406	$ 2,404	$ 6,447