Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts
Balance at beginning of period	$ 15	$ 228
Additions charged to costs and expenses	618	0
Deductions	(133)	(213)
Balance at end of period	500	15
Allowance for prompt pay discounts
Balance at beginning of period	1,844	893
Additions charged to costs and expenses	6,718	6,949
Deductions	(7,524)	(5,998)
Balance at end of period	1,038	1,844
Inventory obsolescence allowance
Balance at beginning of period	2,448	2,220
Additions charged to costs and expenses	2,184	960
Deductions	(2,649)	(732)
Balance at end of period	$ 1,983	$ 2,448