Income Taxes (Details) (USD $)	3 Months Ended				6 Months Ended
	Aug. 31, 2014	May 31, 2014	Aug. 31, 2013	May 31, 2013	Aug. 31, 2014	Aug. 31, 2013
Income Taxes
Effective income tax rate (as a percent)	9.00%		17.40%		12.90%	18.00%
Tax benefit recorded related to the resolution of an uncertain tax position with a foreign tax authority	$ 2,070,000
Asset impairment charges		9,000,000		12,050,000	9,000,000	12,049,000
Tax benefit related to asset impairment charges		$ 860,000		$ 20,000