Disclosure of Compensation Related Costs, Share Based Payments - Schedule of Stock Option Activity (Details) - 2009 Stock Incentive Plan - Employee Stock Option	3 Months Ended
	Jul. 31, 2016 $ / shares shares
Number of Option Shares
Outstanding at the beginning of the period (in shares) | shares	291,200
Granted (in shares) | shares	0
Exercised (in shares) | shares	47,750
Forfeited (in shares) | shares	0
Outstanding at the end of the period (in shares) | shares	243,450
Weighted Average Option Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 37.46
Granted (in dollars per share) | $ / shares	0.00
Exercised (in dollars per share) | $ / shares	33.47
Forfeited (in dollars per share) | $ / shares	0.00
Outstanding at the end of the period (in dollars per share) | $ / shares	$ 38.24