Consolidated Financial Statement Details (Components of Accrued Expenses and Other Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued bonuses	$ 13,281	$ 16,743
Accrued commissions and salaries	7,855	6,943
Lease incentive obligations	3,881	4,635
Customer credit balances	3,928	4,652
Deferred rent liabilities	2,788	4,548
Taxes payable	3,247	5,517
Unrecognized tax benefit	3,017	1,972
Accrued vacation costs	2,364	2,458
Accrued health care costs	2,411	2,615
Other liabilities	8,646	9,948
Total accrued expenses and other liabilities	51,418	60,031
Less: Long-term portion	7,027	5,632
Accrued expenses and other current liabilities	$ 44,391	$ 54,399