BENEFIT PLANS: (Details Textual) - USD ($)		1 Months Ended			12 Months Ended
	Sep. 04, 2013	Aug. 30, 2013	Aug. 16, 2012	Dec. 31, 2006	Apr. 30, 2016	Apr. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Share-based Compensation, Total					$ 68,000	$ 122,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total					$ 29,000
Defined Benefit Plan, Target Plan Asset Allocations					100.00%	100.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets					8.00%	8.00%
Pension Contributions					$ 0	$ 475,000
Defined Benefit Plan Expected Future Benefit Payments For First Five Years Following Fiscal Year Description					The amount of future annual benefit payments is expected to be between $2,488,000 and $2,745,000 in fiscal years 2017 through 2021, and an aggregate of approximately $11,333,000 is expected to be paid in the fiscal five-year period 2022 through 2026.
Defined Benefit Plan Expected Future Benefit Payments For Second Five Years Following Fiscal Year Description					an aggregate of approximately $11,333,000 is expected to be paid in the fiscal five-year period 2022 through 2026.
Pension Benefit Plan Accelerated Funding					$ 11,688,000
Pension Contributions Towards Accelerated Funding Liability			$ 8,688,000
Defined Benefit Plan, Benefits Paid					2,419,000	4,634,000
Defined Benefit Plan, Benefit Obligation, Period Increase (Decrease)					1,067,000
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months					1,603,000
Defined Benefit Plan, Expected Future Benefit Payments, Year Two					0
Defined Benefit Plan, Expected Future Benefit Payments, Year Three					$ 0
Stock Issued During Period, Shares, Share-based Compensation, Gross					39,000
Common Stock, Capital Shares Reserved for Future Issuance					361,000
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent					$ (268,000)	$ (1,658,000)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefits Paid					2,317,000
Equity Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period				400,000
PBGC [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Contributions	$ 3,243,000	$ 3,243,000	$ 3,000,000
Pension and Other Postretirement and Postemployment Benefit Plans, Liabilities	5,019,000	$ 8,688,000
First Lien Mortgages On Real Property Appraised Value	10,039,000
Defined Pension Plan Real Property Of Mortgage					$ 11,822,000
Pension Contributions Towards Accelerated Funding Liability	$ 426,000
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations					28.00%	29.00%
Fixed Income Securities [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations					20.00%
Fixed Income Securities [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations					50.00%
Other Debt Obligations [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations					0.00%
Other Debt Obligations [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations					30.00%
Equity Securities [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations					50.00%
Equity Securities [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations					80.00%