Financial Instruments Reconciliation of the Change in Level 3 Items (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Apr. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 29.3
Purchases	0
Settlements	(0.8)
Net realized (losses)	(2.0)
Net unrealized (losses)	(1.5)
Ending Balance	25.0
Derivative Contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	9.1
Purchases	0
Settlements	(0.8)
Net realized (losses)	(2.0)
Net unrealized (losses)	(1.5)
Ending Balance	4.8
Convertible Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	20.2
Purchases	0
Settlements	0
Net realized (losses)	0
Net unrealized (losses)	0
Ending Balance	$ 20.2