Summary of Receivable (Detail) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Accounts Receivable and Unbilled Receivable [Line Items]
Accounts receivable	[1]	$ 150,733	$ 222,735
Unbilled receivables	[1]	155,964	158,898
Long-term unbilled receivables	[1]	168,929	160,708
Total receivables		$ 475,626	$ 542,341

[1] On January 1, 2018, the Company adopted the ASC 606 revenue recognition standard and has adjusted prior periods to conform. See Note 2. "New Accounting Pronouncements" for additional information.