INCOME TAXES: - Components of the net deferred income taxes (Details) - USD ($) $ in Thousands	Apr. 30, 2020	Apr. 30, 2019
Deferred income tax assets:
State tax loss carryforwards	$ 4,622	$ 4,287
U.S. Federal NOL carryforward	3,746	2,079
Accrued pension costs	1,258	1,608
Vacation accrual	52	12
Real estate basis differences	4,096	3,725
Other	194	117
Total deferred income tax assets	13,968	11,828
Deferred income tax liabilities:
Depreciable assets	(1,341)	(1,138)
Deferred gains on investment assets	(2,277)	(2,110)
Other		(36)
Total deferred income tax liabilities	(3,618)	(3,284)
Valuation allowance for realization of certain deferred income tax assets	(4,270)	(4,008)
Net deferred income tax asset	$ 6,080	$ 4,536