Stock Appreciation Rights Stock Appreciation Rights Vesting Schedule (Details) (Stock Appreciation Rights (SARs) [Member])	9 Months Ended
	Jan. 31, 2013
Stock Appreciation Rights (SARs) [Member]
Vesting Schedule [Line Items]
Vested In Under One Year	0.00%
Vested At Least One But Less Than Two Years	33.00%
Vested At Least Two But Less Than Three Years	67.00%
Vested Three or More Years	100.00%