SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in Tax Valuation Allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves balance, beginning of year	$ 13,309	$ 15,250	$ 14,309
Charged to Costs and Expenses	67	(61)	0
Charged other Accounts	(1,256)	(1,880)	941
Deductions	0	0	0
Valuation allowances and reserves balance, end of year	12,120	13,309	15,250
Allowance for Doubtful Accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves balance, beginning of year	2,185	417	90
Charged to Costs and Expenses	451	1,768	347
Charged other Accounts		0	0
Deductions	0	0	20
Valuation allowances and reserves balance, end of year	2,636	2,185	417
Reserve for Inventory Obsolescence
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves balance, beginning of year	1,304	410	121
Charged to Costs and Expenses	3,343	2,000	872
Charged other Accounts	0	9	0
Deductions	1,980	1,115	583
Valuation allowances and reserves balance, end of year	$ 2,667	$ 1,304	$ 410