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, 2017
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%