Derivative Financial Instruments (Details) bu in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2016 USD ($) bu	Jul. 31, 2015 USD ($) bu	Jul. 31, 2016 USD ($) bu	Jul. 31, 2015 USD ($) bu
Disclosure Text Block Supplement [Abstract]
Derivative, Nonmonetary Notional Amount, Volume (in US Bushels) | bu			1.3	1.6
Quantity of Bushels under Forward Purchase Contract (in US Bushels) | bu	0.9	1.1	0.9	1.1
Debt Instrument, Collateral Amount | $	$ 110,000		$ 110,000
Gain on Derivative Instruments, Pretax | $	$ 1,136,000	$ 59,000	$ 1,625,000	$ 75,000