SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Description
Balance at beginning of year	$ 5,190	$ 4,201	$ 4,302
Additions charged to expense	9,783	10,247	9,321
Deductions	9,261	9,258	9,422
Balance at End of Year	5,712	5,190	4,201
Reserve for bad debts
Description
Balance at beginning of year	1,197	1,225	1,410
Additions charged to expense	38	27
Reductions credited to expense			(166)
Deductions	107	55	19
Balance at End of Year	1,128	1,197	1,225
Reserve for cash discounts
Description
Balance at beginning of year	724	659	815
Additions charged to expense	9,122	9,268	9,247
Deductions	9,154	9,203	9,403
Balance at End of Year	692	724	659
Deferred tax asset valuation
Description
Balance at beginning of year	3,269	2,317	2,077
Additions charged to expense	623	952	240
Balance at End of Year	$ 3,892	$ 3,269	$ 2,317