Commitments and Contingencies - Narrative - Environmental Reserves and Estimated Recoveries (Details) - USD ($)	6 Months Ended	12 Months Ended
	May. 31, 2015	Nov. 30, 2003	Sep. 01, 2010	May. 31, 2010
Site Contingency [Line Items]
Environmental remediation costs, recognition period	15 years
Pre-Close Environmental Costs	$ 20,000,000
Percentage of environmental costs				12.00%
Non-reimbursable percentage of environmental costs			37.00%
Northrop [Member]
Site Contingency [Line Items]
Current annual billing limitation	6,000,000
Total reimbursable costs under the Northrop Agreement	189,700,000
Environmental costs above the cumulative limitation	33,400,000
Northrop [Member] | Maximum [Member]
Site Contingency [Line Items]
Total reimbursable costs under the Northrop Agreement	$ 189,700,000
Atlantic Research Corporation [Member]
Site Contingency [Line Items]
Pre-Close Environmental Costs		$ 20,000,000.0