Balance Sheet Accounts - Narrative (Details) shares in Millions		3 Months Ended		6 Months Ended		12 Months Ended
	Feb. 28, 2015 a	May. 31, 2015 USD ($) a shares	May. 31, 2014 USD ($)	May. 31, 2015 USD ($) a shares	May. 31, 2014 USD ($)	Nov. 30, 2014 USD ($) shares
Segment Reporting Information [Line Items]
Current and noncurrent Rocketdyne Business integration costs		$ 41,800,000		$ 41,800,000		$ 38,500,000
Savings to restructuring cost ratio				2
Acres of land | a	6,000
Net sales		0	$ 0	$ 0	$ 0
Accumulated other comprehensive loss, net of income tax related to retirement benefit plan		$ 15,100,000		$ 15,100,000
Redeemable common stock, shares outstanding (in shares) | shares		0.1		0.1		0.1
Realized gains and interest		$ 700,000			$ (100,000)
Number of common shares repurchased (in shares) | shares						3.5
Purchase of treasury stock						$ 64,500,000
Hillsborough [Member]
Segment Reporting Information [Line Items]
Acres of land | a		550		700
Total purchase price		$ 57,000,000		$ 57,000,000
Cash proceeds from sale of land		46,700,000
Cash received at initial closing		40,000,000
Income from continuing operations before income taxes from land sale		30,600,000		30,600,000
Hillsborough [Member] | Notes Receivable [Member]
Segment Reporting Information [Line Items]
Promissory note		10,300,000		10,300,000
Hillsborough [Member] | Interest Bearing Notes Receivable [Member]
Segment Reporting Information [Line Items]
Promissory note		9,000,000.0		9,000,000.0
Hillsborough [Member] | Interest Bearing Notes Receivable, 7% Promissory Note [Member]
Segment Reporting Information [Line Items]
Promissory note		$ 3,000,000.0		$ 3,000,000.0
Promissory note, interest rate		7.00%		7.00%
Promissory note, maturity		7 years
Contingent decrease in principal of receivable		$ 1,000,000.0
Hillsborough [Member] | Interest Bearing Notes Receivable, 7% Contingent Promissory Note [Member]
Segment Reporting Information [Line Items]
Promissory note		$ 6,000,000.0		$ 6,000,000.0
Promissory note, interest rate		7.00%		7.00%
Promissory note, maturity		7 years
Hillsborough [Member] | Non-interest Bearing Notes Receivable [Member]
Segment Reporting Information [Line Items]
Promissory note		$ 1,300,000		$ 1,300,000
Land Held Back [Member]
Segment Reporting Information [Line Items]
Acres of land | a		150
Area 40 [Member]
Segment Reporting Information [Line Items]
Acres of land | a		50
Developable Portions of Holdback Acreage [Member]
Segment Reporting Information [Line Items]
Total purchase price		$ 6,700,000		6,700,000
Hillsborough [Member]
Segment Reporting Information [Line Items]
Acres of land | a	550
Energy Business [Member] | Aerospace and Defense [Member]
Segment Reporting Information [Line Items]
Net sales				400,000		$ 600,000
Expenses incurred to divest				$ 2,500,000