Schedule of Trade Accounts Receivable (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 213,126	$ 216,477
Allowance for sales credit memos	(4,564)	(4,631)
Total accounts receivable net	208,562	211,846
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	178,846	190,820
Unbilled trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 34,280	$ 25,657