Commitments and Contingencies Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2008
Sale Leaseback Transaction [Line Items]
Deferred gains on sale-leasebacks	$ 40.5	$ 45.9	$ 144.5
Minimum [Member]
Sale Leaseback Transaction [Line Items]
Amortization Period of Sale-Leaseback Deferred Gains	15 years
Maximum [Member]
Sale Leaseback Transaction [Line Items]
Amortization Period of Sale-Leaseback Deferred Gains	20 years