Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Apr. 30, 2016
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$ 105,700	$ 96,600	$ 111,500
Unrecognized Tax Benefits, Period Increase (Decrease)	(5,800)	10,300
Effect of anticipated settlements of audit issues and expiring statutes of limitations	7,500
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	11,600
Accrued income taxes and reserves for uncertain tax positions	$ 68,832	$ 67,732	$ 373,754
Effective Income Tax Rate Reconciliation, Percent	38.80%	43.70%
Net Discreet Tax Expense (Benefit)	$ 10,800	$ 26,600
Effective tax rate, impact of discrete tax items	(2.50%)	(6.30%)