Valuation And Qualifying Accounts (In Thousands) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts (1)
Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward]
Balance at Beginning of Period	$ 3,161	$ 900	$ 0
Additions	3,852	3,209	900
Deductions Charged to Reserves	(3,308)	(948)	0
Balance at End of Period	3,705	3,161	900
Accounts receivable allowances (2)
Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward]
Balance at Beginning of Period	9,533	10,783	11,618
Additions	168,945	122,792	93,887
Deductions Charged to Reserves	(166,418)	(124,042)	(94,722)
Balance at End of Period	12,060	9,533	10,783
Rebates, fees and returns reserves(1)
Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward]
Balance at Beginning of Period	89,466	45,162	43,892
Additions	255,471	186,941	120,293
Deductions Charged to Reserves	(244,235)	(142,637)	(119,023)
Balance at End of Period	100,702	89,466	45,162
Valuation allowance for deferred tax assets (3)
Valuation Allowance for Impairment of Recognized Servicing Assets [Roll Forward]
Balance at Beginning of Period	1,429	11,859	33,557
Additions	4,732	632	0
Deductions Charged to Reserves	(564)	(11,062)	(21,698)
Balance at End of Period	$ 5,597	$ 1,429	$ 11,859