Fair Value Measurement (Assets Remeasured At Fair Value On Non-Recurring Basis) (Details) (Non-Recurring, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2015	Apr. 30, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired mortgage loans held for investment	$ 56,784	$ 69,131
As a percentage of total assets	1.30%	1.50%
Loss, Impaired mortgage loans held for investment	(1,678)	(3,739)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired mortgage loans held for investment	0	0
As a percentage of total assets	0.00%	0.00%
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired mortgage loans held for investment	0	0
As a percentage of total assets	0.00%	0.00%
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired mortgage loans held for investment	$ 56,784	$ 69,131
As a percentage of total assets	1.30%	1.50%