Credit Risk Assessment for Long-term Receivables (Detail) - USD ($) $ in Thousands	Oct. 31, 2016	Jan. 31, 2016
Accounts and Financing Receivable [Line Items]
Term receivables, long-term	$ 251,416	$ 268,657
S&P credit rating, AAA+ through BBB-
Accounts and Financing Receivable [Line Items]
Term receivables, long-term	176,338	195,764
S&P credit rating, BB+ and lower
Accounts and Financing Receivable [Line Items]
Term receivables, long-term	35,286	22,520
S&P credit rating
Accounts and Financing Receivable [Line Items]
Term receivables, long-term	211,624	218,284
Internal Credit Rating
Accounts and Financing Receivable [Line Items]
Term receivables, long-term	$ 39,792	$ 50,373