Legal Proceedings And Contingent Liabilities (Summary Of Employee Exposure Standards By Regulatory Agencies)	6 Months Ended
	Nov. 30, 2011
Occupational Safety And Health Administration [Member]
Loss Contingencies [Line Items]
Employee exposure standards, nanograms per cubic meter	5,000
National Institute For Occupational Safety And Health [Member]
Loss Contingencies [Line Items]
Employee exposure standards, nanograms per cubic meter	1,000
California Environmental Protection Agency [Member]
Loss Contingencies [Line Items]
Employee exposure standards, nanograms per cubic meter	200