Federal, State and Local Income Taxes - Provision for income taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013	Oct. 31, 2012
Current tax expense:
Federal	$ 838	$ 879	$ 1,054	$ 1,327
State and local	46	29	74	102
Current tax expense	884	908	1,128	1,429
Deferred tax expense:
Federal	24	(31)	530	436
State and local	10	30	91	117
Deferred tax expense	34	(1)	621	553
Income tax provision:	$ 918	$ 907	$ 1,749	$ 1,982

Amount of current federal tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of current income tax expense (benefit) pertaining to taxable income (loss) from continuing operations.

Amount of current state and local tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of deferred federal income tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of deferred state and local tax expense (benefit) pertaining to income (loss) from continuing operations.