Investments - Composition of income from securities transactions (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2014		Apr. 30, 2013		Apr. 30, 2012
Investment Income, Net [Abstract]
Dividend income	$ 147		$ 124		$ 68
Interest income	5		4		16
Realized gains (losses) on sales of securities available-for-sale reclassified from Accumulated Other Comprehensive Income					(11)
Interest expense	(5)
Other	31	[1]	(2)	[1]	(3)	[1]
Total income from securities transactions, net	$ 178		$ 126		$ 70

[1] Other amounts include $36,000 which was reclassified from Accumulated Other Comprehensive Income in the Consolidated Balance Sheets to the Consolidated Statements of Income in fiscal 2014.