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Income Taxes - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Aug. 31, 2013
Income Tax Disclosure [Abstract]  
Deferred tax assets $ 42
Federal net operating loss and tax credit carryforwards 28
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