Schedule of Trade Accounts Receivable (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 137,337	$ 156,384
Allowance for sales credit memos	(1,752)	(1,540)
Total accounts receivable net	135,585	154,844
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	122,210	128,757
Unbilled accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 15,127	$ 27,627