Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 1,119	$ 977	$ 969
Charged to income tax (benefit) expense	146	321	136
Deductions from Reserves	(323)	(179)	(128)
Other Adjustments	0	0	0
Balance at End of Year	942	1,119	977
Rebates and allowances
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	4,654	2,860	2,297
Charged to income tax (benefit) expense	16,729	13,202	9,568
Deductions from Reserves	(14,237)	(11,047)	(8,351)
Other Adjustments	(161)	(361)	(654)
Balance at End of Year	$ 6,985	$ 4,654	$ 2,860