Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) segment	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment			3
Segment Information
Net sales	$ 308,007	$ 263,002	$ 552,786	$ 482,869
Income (Loss) from Operations	60,744	45,137	93,540	67,768
Total Assets	1,085,887	1,041,477	1,085,887	1,041,477	$ 1,037,523
Cash and cash equivalent	155,035	140,950	155,035	140,950	168,514	$ 226,537
Intersegment elimination
Segment Information
Net sales	7,626	6,650	15,127	12,596
Administrative and all other
Segment Information
Income (Loss) from Operations	(1,125)	(1,083)	(2,800)	(3,190)
Total Assets	(194,107)	(104,804)	(194,107)	(104,804)	(150,970)
Cash and cash equivalent	71,800	69,800	71,800	69,800	80,200
North America
Segment Information
Net sales	259,822	215,739	466,034	399,510
Income (Loss) from Operations	58,483	42,011	94,450	68,778
Total Assets	1,042,765	915,661	1,042,765	915,661	953,033
North America | Intersegment elimination
Segment Information
Net sales	578	928	1,206	1,778
Europe
Segment Information
Net sales	45,784	45,234	82,077	79,615
Income (Loss) from Operations	2,845	4,138	1,198	2,304
Total Assets	208,609	205,614	208,609	205,614	208,640
Europe | Intersegment elimination
Segment Information
Net sales	251	102	600	249
Asia/Pacific
Segment Information
Net sales	2,401	2,029	4,675	3,744
Income (Loss) from Operations	541	71	692	(124)
Total Assets	28,620	25,006	28,620	25,006	$ 26,820
Asia/Pacific | Intersegment elimination
Segment Information
Net sales	$ 6,797	$ 5,620	$ 13,321	$ 10,569