Accounts Receivable, Net - Accounts Receivables Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accounts Receivable, Net, Current [Abstract]
Trade accounts receivable	$ 120,878	$ 107,174
Unbilled revenue	67,719	47,789
Total accounts receivable	188,597	154,963
Allowance for doubtful accounts	(12,842)	(11,915)
Accounts receivable, net	$ 175,755	$ 143,048