Accrued Expenses And Other Liabilities (Schedule Of Accrued Expenses & Other Current Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued compensation and benefits	$ 21,427	$ 43,970
Fulfillment, freight, and duties	15,983	12,234
Professional services	10,041	11,124
Accrued rent and occupancy	4,096	6,956
Return liabilities	7,957	6,429
Sales/use and value added taxes payable	8,174	5,601
Royalties payable and deferred revenue	3,663	3,356
Other	6,863	12,501
Total accrued expenses and other liabilities	$ 78,204	102,171
Accrued inducements		$ 3,000