SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts
Valuation and qualifying accounts
Balance at Beginning of Year	$ 996	$ 895	$ 1,142
Charged to Costs and Expenses	569	66	(83)
Valuation Allowances and Reserves, Charged to Other Accounts	201	0	0
Deductions	0	(35)	164
Balance at End of Year	1,364	996	895
Sales Returns and Allowances [Member]
Valuation and qualifying accounts
Balance at Beginning of Year	2,956	3,050	2,706
Charged to Costs and Expenses	361	(94)	344
Valuation Allowances and Reserves, Charged to Other Accounts	0	0	0
Deductions	0	0	0
Balance at End of Year	3,317	2,956	3,050
Allowance for deferred tax assets
Valuation and qualifying accounts
Balance at Beginning of Year	11,114	6,868	7,575
Charged to Costs and Expenses	2,477	5,765	358
Valuation Allowances and Reserves, Charged to Other Accounts		0	0
Deductions	337	1,519	1,065
Balance at End of Year	$ 13,254	$ 11,114	$ 6,868