Schedule of Trade Accounts Receivable (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 207,427	$ 216,477
Allowance for sales credit memos	(5,028)	(4,631)
Total accounts receivable net	202,399	211,846
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	189,022	190,820
Unbilled trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 18,405	$ 25,657