Comprehensive Income - Components of comprehensive income that are included in Consolidated Statement of Changes in Shareholders' Equity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jul. 31, 2013	Jul. 31, 2012
Comprehensive Income (Loss) Note [Abstract]
Change in unrealized gains (losses) on securities during the period, before tax	$ (4)	$ 42
Change in unrealized gains (losses) on securities during the period, tax benefit	1	(15)
Change in unrealized gains (losses) on securities during the period, net of tax	(3)	27
Other comprehensive income (loss), available-for-sale securities adjustment, before tax	(4)	42
Other comprehensive income (loss), available-for-sale securities, tax benefit	1	(15)
Other comprehensive income (loss), available-for-sale securities adjustment, net of tax	$ (3)	$ 27