Revenue from Contracts with Customers - Deferred Revenues (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Deferred Revenue Arrangement [Line Items]
Deferred revenue, current	$ 164,624	$ 143,186	$ 143,186
Deferred revenue, noncurrent	20,423	17,136	$ 17,136
Total	185,047	160,322
ASC 606
Deferred Revenue Arrangement [Line Items]
Deferred revenue, current	152,204	130,579
Deferred revenue, noncurrent	18,286	15,419
Total	170,490	145,998
Operating Leases
Deferred Revenue Arrangement [Line Items]
Deferred revenue, current	12,420	12,607
Deferred revenue, noncurrent	2,137	1,717
Total	$ 14,557	$ 14,324