Site Consolidation - Consolidation Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		14 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019
Restructuring Cost and Reserve [Line Items]
Total site consolidation expense	$ 117	$ 1,621	$ 4,900
Employee severance and relocation
Restructuring Cost and Reserve [Line Items]
Total site consolidation expense	77	1,621
Facility and other expenses
Restructuring Cost and Reserve [Line Items]
Total site consolidation expense	$ 40	$ 0