Other Operating Income (Details) (USD $)	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended	1 Months Ended
	Dec. 31, 2012	May 31, 2013	Feb. 28, 2013	May 31, 2012	May 31, 2013	May 31, 2012	Aug. 31, 2012 Assets Held-For-Sale [Member]	Dec. 31, 2012 Notes Receivable And Direct Financing Leases From Property Disposition [Member]
Carrying value of assets at time of sale	$ 38,400,000
Proceeds from sale	29,700,000							8,700,000
Period in which remaining proceeds will be received			24 months
Gain on disposition of property			1,000,000
Lease revenue		1,089,000		2,056,000	3,524,000	4,605,000	4,800,000
Note prepayment exclusion amount			5,000,000
Debt prepayment			20,000,000
Straight-line lease adjustment and franchise rights			$ 800,000