Income Taxes (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Nov. 30, 2012
Income Taxes (Textual) [Abstract]
Deferred tax assets	$ 39
Federal net operating loss and tax credit carryforwards	25
State net operating loss carryforwards	7
Differences between financial and tax reporting	$ 7
Federal net operating loss and tax credit carryforwards life expectancy	20 years
State net operating loss carryforwards life expectancy minimum	5 years
State net operating loss carryforwards life expectancy maximum	20 years