Nature of Operations - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) sales_agency region sales_agent	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Inventory adjustments	$ 0		$ 3,300
Reduction of full-time equivalent headcount, percent		51.00%
Decrease in operating expense	$ 3,600	$ 8,400
Restructuring costs and asset impairment charges		1,800
Number of geographic regions | region	6
Sales Coverage, Number Of Sales Agencies | sales_agency	50
Number of sales agents | sales_agent	10
Provision for slow-moving and obsolete inventories	$ (17)	1,400	(3,281)
Restructuring	111	1,662	0
Facilities
Restructuring Cost and Reserve [Line Items]
Restructuring	$ 100	$ 700
Military maritime
Restructuring Cost and Reserve [Line Items]
Increase (decrease) in revenue			$ (33,900)