Accounts Receivable (Accounts Receivable) (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Trade receivables		$ 361,722	$ 333,954
Allowance for doubtful accounts		(5,333)	(4,771)
Sales returns allowance	[1]	0	(4,127)
Other allowances		(2,640)	(2,164)
Accounts receivable, net		$ 353,749	$ 322,892

[1] Effective January 1, 2018, as part of the Company’s adoption of Topic 606, the Company has recorded a liability for estimated returns of inventory as a refund liability within accrued expenses and other liabilities. These balances were previously presented as an allowance within accounts receivable. See Note 6 for further details.