Income Taxes (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 9 Months Ended
Feb. 28, 2014
Feb. 28, 2013
Feb. 28, 2014
Feb. 28, 2013
Income Tax Disclosure [Abstract]        
Effective income tax rate 17.90% 9.60% 56.90% 20.90%
Nondeductible permanent expenses due to impairment $ 233.0   $ 233.0  
Increase (decrease) in tax provision from changes in state and international reorganizations $ 3.2 $ (30.3) $ (22.8) $ (34.0)
Increase in effective income tax rates (4.00%) 9.00% 32.80% 6.70%