Summary of Receivable (Detail) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Accounts Receivable and Unbilled Receivable [Line Items]
Accounts receivable	[1]	$ 141,384	$ 222,735
Unbilled receivables	[1]	151,354	158,898
Long-term unbilled receivables	[1]	169,330	160,708
Total receivables		$ 462,068	$ 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.