Notes payable (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2012	Jan. 31, 2011
Debt Instrument [Line Items]
Notes payable	$ 214,573	$ 209,348
Term loan due 2013, current portion	(1,349)	(2,000)
Other, current portion	(1,349)
Notes payable, long-term	213,224	207,348
4.00% Debentures due 2031
Debt Instrument [Line Items]
Notes payable	213,224
6.25% Debentures due 2026, issued 2006
Debt Instrument [Line Items]
Notes payable		157,843
6.25% Debentures due 2026, issued fiscal 2011
Debt Instrument [Line Items]
Notes payable		31,705
Term Loan due 2013
Debt Instrument [Line Items]
Notes payable		18,500
Term loan due 2013, current portion		(2,000)
Other
Debt Instrument [Line Items]
Notes payable	$ 1,349	$ 1,300