Stock-based Compensation (Details Textual) - May. 31, 2015	USD ($) share_based_compensation_plan $ / shares shares
Share Based Compensation (Textual) [Abstract]
Number Of Share-Based Compensation Plans | share_based_compensation_plan	1
Shares authorized (shares)	1,500,000
Share for future issuance (shares)	1,397,482
Unrecognized compensation cost | $	$ 7,104,423
Employee Stock Purchase Plan [Member]
Share Based Compensation (Textual) [Abstract]
Term of offering under stock purchase plan	24 months
Granted option lower than	85.00%
Restricted common stock under plan | $	$ 25,000
Common stock purchased during period (shares)	5,000
Share-based Compensation Arrangement, By Share-based Payment Award, Common Shares Estimated To Be Issued	29,995
Restricted Stock [Member]
Share Based Compensation (Textual) [Abstract]
Vesting ratably term	3 years
Performance Shares [Member]
Share Based Compensation (Textual) [Abstract]
Vesting ratably term	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	28,553
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares	$ 46.65
Stock Appreciation Rights (SARs) [Member]
Share Based Compensation (Textual) [Abstract]
Vesting ratably term	3 years
Term for the contract	7 years
Outstanding Average contractual term	3 years 10 months 05 days
Outstanding Aggregate intrinsic value | $	$ 17,600,000
Average remaining contractual term	3 years 1 month 15 days
Aggregate remaining intrinsic value | $	$ 12,400,000