Notes Payable - Redemption Prices Expressed as a Percentage of Principal, Plus any Accrued and Unpaid Interest (Details) (4.00% Debentures due 2031, Convertible Subordinated Debt)	12 Months Ended
	Jan. 31, 2015
Redemption Period Beginning on April 5, 2016 and ending on March 31, 2017
Debt Instrument
Debentures redemption price	101.143%
Redemption Period Beginning on April 1, 2017 and ending on March 31, 2018
Debt Instrument
Debentures redemption price	100.571%
Redepmption Period Beginning on April 1, 2018 and thereafter
Debt Instrument
Debentures redemption price	100.00%