Fair Value Fair Value (Summary Of Carrying Amounts And Estimated Fair Values Of Company's Financial Instruments) (Details) - USD ($) $ in Thousands	Jul. 31, 2017	Apr. 30, 2017	Jul. 31, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash & cash equivalents	$ 551,566	$ 1,011,331	$ 306,871
Cash and cash equivalents, Estimated Fair Value	551,566	1,011,331
Cash and cash equivalents - restricted, Carrying Amount	116,594	106,208	122,025
Cash and cash equivalents - restricted, Estimated Fair Value	116,594	106,208
Receivables, net	91,004	162,775	103,425
Receivables, net - short-term, Estimated Fair Value	91,004	162,775
Accounts Receivable, Net, Noncurrent	60,945	52,898	56,514
Receivables, net - long-term, Estimated Fair Value	60,945	52,898	56,514
Long-term Debt, Gross	1,502,694	1,502,735
Long-term borrowings, Estimated Fair Value	1,595,945	1,569,033
Contingent consideration payments, estimated fair value	9,125	10,428
Contingent consideration payments, carrying amount	$ 9,125	$ 10,428
Level 1
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash and cash equivalents, Estimated Fair Value			306,871
Cash and cash equivalents - restricted, Estimated Fair Value			122,025
Receivables, net - short-term, Estimated Fair Value			103,425
Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term Debt, Gross			1,502,747
Long-term borrowings, Estimated Fair Value			1,606,364
Contingent consideration payments, estimated fair value			8,347
Contingent consideration payments, carrying amount			$ 8,347