Litigation And Related Contingencies (Details) $ in Millions	9 Months Ended
	Jan. 31, 2017 USD ($) securities lawsuit	Apr. 30, 2016 USD ($) loan	Jan. 31, 2016 USD ($)
Loss Contingencies [Line Items]
Loss Contingency Accrual	$ 1.7	$ 2.3	$ 6.2
Securitization Transactions | securities	39
SCC [Member]
Loss Contingencies [Line Items]
Original Principal Amount of Loans Securitized	$ 14,000.0
SCC [Member] | Claims with Knowledge of Outstanding Principal Amount [Member]
Loss Contingencies [Line Items]
Initial principal on loans securitized	$ 4,000.0
MGRID LLC v. Merrill Lynch Mortgage Lending Inc [Member]
Loss Contingencies [Line Items]
Number Of Lawsuits | lawsuit	22
MGRID LLC v. Merrill Lynch Mortgage Lending Inc [Member] | SCC [Member]
Loss Contingencies [Line Items]
Loans Sold To Trust, With Claims of Breach of Contract and Indemnity | loan		159