Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jul. 31, 2012	Jul. 31, 2011
Comprehensive Income (Loss) Note [Abstract]
Change in unrealized gains on securities during the period, before tax	$ 42	$ (80)
Change in unrealized gains on securities during the period, tax expense	(18)
Change in unrealized gains on securities during the period, tax benefit	3	28
Change in unrealized gains on securities during the period, net of tax	27	(52)
Adjustments for losses realized in net income, before tax		5
Adjustments for losses realized in net income, tax expense		(2)
Adjustments for losses realized in net income, tax benefit
Adjustments for losses realized in net income, net of tax		3
Other comprehensive income (loss), available-for-sale securities adjustment, before tax	42	(75)
Other comprehensive income (loss), available-for-sale securities, tax expense	(18)	(2)
Other comprehensive income (loss), available-for-sale securities, tax benefit	3	28
Other comprehensive income (loss), available-for-sale securities adjustment, net of tax	$ 27	$ (49)