Revenue - Revenue from External Customers by Geographic Areas (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Net sales			$ 417,639	$ 546,076
North America
Disaggregation of Revenue [Line Items]
Net sales	$ 376,276	$ 483,302
Pacific Rim
Disaggregation of Revenue [Line Items]
Net sales	25,869	39,180
Europe
Disaggregation of Revenue [Line Items]
Net sales	9,339	16,562
Other
Disaggregation of Revenue [Line Items]
Net sales	6,155	7,032
Energy
Disaggregation of Revenue [Line Items]
Net sales	149,282	222,779
Industrial
Disaggregation of Revenue [Line Items]
Net sales	131,026	180,111
Transportation
Disaggregation of Revenue [Line Items]
Net sales	$ 137,331	$ 143,186