Contract Assets and Contract Liabilities - Additional Information (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Contract With Customer Asset And Liability [Line Items]
Unbilled receivables	$ 49,361		$ 28,153
Advanced billings	147,935		$ 73,756
ASC 606
Contract With Customer Asset And Liability [Line Items]
Unbilled receivables		$ 36,696
Advanced billings		112,613
ASC 606 | Impact of Adoption of ASC 606 - Adjustments
Contract With Customer Asset And Liability [Line Items]
Unbilled receivables		8,543
Advanced billings	$ (41,732)	$ 38,857