Schedule of Trade Accounts Receivable (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 131,352	$ 156,384
Allowance for sales credit memos	(2,100)	(1,540)
Total accounts receivable net	129,252	154,844
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	113,207	128,757
Unbilled accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 18,145	$ 27,627