Loss Per Share of Common Stock - Schedule of Potentially Dilutive Securities Excluded from Computation (Parenthetical) (Detail) (Convertible Subordinated Debentures, Bearing Interest at 4.0625% Maturing in December 2039 [Member])	May 31, 2014	May 31, 2013
Convertible Subordinated Debentures, Bearing Interest at 4.0625% Maturing in December 2039 [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Interest on debt instrument	4.0625%	4.0625%