Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 9,694	$ 11,358	$ 12,201
Additions Charged to Costs and Expenses	33,436	30,818	30,738
Deductions	31,612	32,482	31,581
Balance at End of Period	11,518	9,694	11,358
Doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	33	88	112
Additions Charged to Costs and Expenses	429	63	0
Deductions	13	118	24
Balance at End of Period	449	33	88
Cash discounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	365	273	367
Additions Charged to Costs and Expenses	28,154	27,685	25,237
Deductions	28,202	27,593	25,331
Balance at End of Period	317	365	273
Deferred tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	3,664	4,439	3,900
Additions Charged to Costs and Expenses	153	0	539
Deductions	0	775	0
Balance at End of Period	3,817	3,664	4,439
Sales returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	5,632	6,558	7,822
Additions Charged to Costs and Expenses	4,700	3,070	4,962
Deductions	3,397	3,996	6,226
Balance at End of Period	6,935	$ 5,632	$ 6,558
Accounting Standards Update 2014-09 | Sales returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Additions Charged to Costs and Expenses	$ 2,525