Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Income Tax Disclosure [Abstract]
Effective income tax rate	38.00%	36.30%	34.90%	36.20%
Excess tax benefit related to stock-based compensation			$ 1.2