Litigation And Other Related Contingencies (Details) $ in Thousands	9 Months Ended
	Jan. 31, 2018 USD ($) loan securities lawsuit	Apr. 30, 2017 USD ($)	Jan. 31, 2017 USD ($)	Apr. 30, 2016 USD ($)
Litigation And Related Contingencies [Abstract]
Loss contingency accrual	$ 2,500	$ 2,300	$ 1,700
Number of loans sold to the trust | loan	96
Loans sold to trust, with claims of breach of contract and indemnity | loan	649
Loss Contingencies [Line Items]
Securitization transactions | securities	39
Principal assets of SCC	$ 303,000
Scc
Litigation And Related Contingencies [Abstract]
Loss contingency accrual	0	$ 4,500	$ 4,500	$ 65,265
Loss Contingencies [Line Items]
Original principal amount of loans securitized	14,000,000
Scc | Claims with Knowledge of Outstanding Principal Amount
Loss Contingencies [Line Items]
Initial principal on loans securitized	$ 3,400,000
MGRID LLC v. Merrill Lynch Mortgage Lending Inc
Loss Contingencies [Line Items]
Number of lawsuits | lawsuit	21