Segment Information (Net Sales by Region or Origin and Long-Lived Assets by Region of Domicile) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales:	$ 258,131	$ 299,236	$ 262,655	$ 227,417	$ 240,913	$ 280,086	$ 266,036	$ 215,337	$ 1,047,439	$ 1,002,372	$ 986,918
Long-lived assets	97,389				97,046				97,389	97,046	101,779
North America
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales:									1,030,638	990,772	977,942
Long-lived assets	96,847				96,342				96,847	96,342	97,956
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales:									0	0	1,131
Long-lived assets	0				0				0	0	3,222
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales:									16,801	11,600	7,845
Long-lived assets	$ 542				$ 704				$ 542	$ 704	$ 601