Fair Value Fair Value (Summary Of Carrying Amounts And Estimated Fair Values Of Company's Financial Instruments) (Details) - USD ($) $ in Thousands	Jan. 31, 2017	Apr. 30, 2016	Jan. 31, 2016	Apr. 30, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash & cash equivalents	$ 221,172	$ 896,801	$ 189,511	$ 2,007,190
Cash and cash equivalents, Estimated Fair Value	221,172	896,801
Cash and cash equivalents - restricted, Carrying Amount	70,166	104,110	69,649
Cash and cash equivalents - restricted, Estimated Fair Value	70,166	104,110
Receivables, net	787,865	153,116	829,774
Receivables, net - short-term, Estimated Fair Value	787,865	153,116
Accounts Receivable, Net, Noncurrent	66,251	60,407	76,471
Receivables, net - long-term, Estimated Fair Value	66,251	60,407	76,471
Long-term Debt	2,593,564	1,492,201
Long-term borrowings, Estimated Fair Value	2,672,370	1,566,098
Contingent consideration payments, carrying amount	9,332	8,657
Contingent consideration payments, estimated fair value	$ 9,332	$ 8,657
Level 1
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash and cash equivalents, Estimated Fair Value			189,511
Cash and cash equivalents - restricted, Estimated Fair Value			69,649
Receivables, net - short-term, Estimated Fair Value			829,774
Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-term Debt			2,616,640
Long-term borrowings, Estimated Fair Value			2,709,807
Contingent consideration payments, carrying amount			13,903
Contingent consideration payments, estimated fair value			$ 13,903