Investments - Composition of income from securities transactions (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2013		Apr. 30, 2012		Apr. 30, 2011
Investment Income, Net [Abstract]
Dividend income	$ 124		$ 68		$ 16
Interest income	4	[1]	16	[1]	118	[1]
Realized and unrealized gains (losses) on securities available-for-sale		[2]	(11)	[2]	(63)	[2]
Interest expense					(2)
Other	(2)		(3)		(4)
Total income from securities transactions, net	$ 126		$ 70		$ 65

[1] Interest income was recorded net of bond premium amortization of $14,000 during fiscal year 2011.

[2] These amounts were reclassified from Accumulated Other Comprehensive Income in the Consolidated Balance Sheets to the Consolidated Statements of Income.