Organization and Summary of Significant Accounting Policies - Contract Assets and Contract Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Short-term unbilled receivables - included in accounts receivable and unbilled receivables	$ 9,475	$ 4,590
Long-term unbilled receivables - included in other long-term assets	15,573	9,475
Total contract assets	25,048	14,065
Short-term deferred revenues	87,777	78,774
Long-term deferred revenues	10,634	10,623
Total contract liabilities	$ 98,411	$ 89,397