SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts and revenue reserves
Movement in Valuation Allowances and Reserves
Balance at beginning of period	$ 11,489	$ 16,405	$ 16,528
Charges to Earnings	48,445	28,930	17,733
Charges to Other Accounts	(573)	(1,006)	(695)
Deductions	(40,501)	(32,840)	(17,161)
Balance at end of period	18,860	11,489	16,405
Sales returns accrual
Movement in Valuation Allowances and Reserves
Balance at beginning of period	0	80	828
Charges to Earnings		0	14,998
Charges to Other Accounts		(80)	(962)
Deductions		0	(14,784)
Balance at end of period		0	80
Deferred tax valuation allowance
Movement in Valuation Allowances and Reserves
Balance at beginning of period	132,598	88,170	90,482
Charges to Earnings	(20,746)	38,144	(837)
Charges to Other Accounts	4,001	6,284	(1,475)
Deductions	0	0	0
Balance at end of period	115,853	132,598	88,170
Other reserves
Movement in Valuation Allowances and Reserves
Balance at beginning of period	2,544	2,822	2,801
Balance at end of period	$ 7,734	$ 2,544	$ 2,822