Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 13,105	$ 10,867	$ 10,954
Additions Charged to Costs and Expenses	34,207	32,718	29,424
Deductions	35,111	30,480	29,511
Balance at End of Period	12,201	13,105	10,867
Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	37	192	318
Additions Charged to Costs and Expenses	75	31	198
Deductions	0	186	324
Balance at End of Period	112	37	192
Cash Discounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	415	241	259
Additions Charged to Costs and Expenses	25,616	25,801	25,207
Deductions	25,664	25,627	25,225
Balance at End of Period	367	415	241
Deferred Tax Valuation Allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	4,933	6,014	6,310
Additions Charged to Costs and Expenses	0	0	0
Deductions	1,033	1,081	296
Balance at End of Period	3,900	4,933	6,014
Sales Returns [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	7,720	4,420	4,067
Additions Charged to Costs and Expenses	8,516	6,886	4,019
Deductions	8,414	3,586	3,666
Balance at End of Period	$ 7,822	$ 7,720	$ 4,420