Schedule of Trade Accounts Receivable (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 222,610	$ 269,154
Allowance for sales credit memos	(5,590)	(4,126)
Total accounts receivable net	217,020	265,028
Trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	188,304	234,473
Unbilled trade accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 34,306	$ 34,681