Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012
Comprehensive Income (Loss) Note [Abstract]
Change in unrealized gains (losses) on securities during the period, before tax			$ 70	$ (1)
Change in unrealized gains (losses) on securities during the period, tax expense			(78)
Change in unrealized gains (losses) on securities during the period, tax benefit			54
Change in unrealized gains (losses) on securities during the period, net of tax			46	(1)
Add: Losses realized in net income, before tax				22
Add: Losses realized in net income, tax expense				(8)
Add: Losses realized in net income, tax benefit
Add: Losses realized in net income, net of tax				14
Other comprehensive income (loss), available-for-sale securities adjustment, before tax			70	21
Other comprehensive income (loss), available-for-sale securities, tax expense			(78)	(8)
Other comprehensive income (loss), available-for-sale securities, tax benefit			54
Other comprehensive income (loss), available-for-sale securities adjustment, net of tax	$ 19	$ 43	$ 46	$ 13