Term Receivable and Trade Accounts Receivable Balances (Detail) - USD ($) $ in Thousands	Jul. 31, 2015	Jan. 31, 2015
Accounts and Financing Receivable [Line Items]
Trade accounts receivable, net	$ 443,797	$ 546,622
Term receivables, long-term	266,092	301,862
Trade accounts receivable
Accounts and Financing Receivable [Line Items]
Trade accounts receivable, net	97,839	208,996
Term receivables, short-term
Accounts and Financing Receivable [Line Items]
Trade accounts receivable, net	$ 345,958	$ 337,626