Commitments and Contingencies Environmental Matter (Details) $ in Millions	6 Months Ended
	Jul. 31, 2015 USD ($)
EPA's FFS remediation approaches [Member] | Minimum [Member]
Environmental Matter Disclosure [Line Items]
Estimated Remediation Costs Low Estimate	$ 360.0
EPA's FFS remediation approaches [Member] | Maximum [Member]
Environmental Matter Disclosure [Line Items]
Estimated Remediation Costs High Estimate	3,250.0
EPA-recommended remediation approach [Member] | Minimum [Member]
Environmental Matter Disclosure [Line Items]
Estimated Remediation Costs EPA Preferred Method Low Estimate	950.0
EPA-recommended remediation approach [Member] | Maximum [Member]
Environmental Matter Disclosure [Line Items]
Estimated Remediation Costs EPA Preferred Method High Estimate	1,731.0
CPG Preferred Approach [Member] | Minimum [Member]
Environmental Matter Disclosure [Line Items]
Estimated Remediation Costs CPG Recommended Approach	$ 483.0