BENEFIT PLANS - Additional information (Details) - USD ($)			1 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Oct. 31, 2020	Sep. 30, 2020	Apr. 30, 2022	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Share-based Compensation, Total						$ 132,000	$ 113,000
Weighted-average remaining vesting period						3 years
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent						$ 1,844,000	564,000
Payment for Pension Benefits							7,280,000
Expected lump sum payments from the pension funds						7,280,000	2,929,000
Estimated Pension Settlement Expenses Before Tax						$ 2,049,000	$ 2,049,000
Defined Benefit Plan Expected Future Benefit Payments For First Five Years Following Fiscal Year Description						The amount of future annual benefit payments to pension plan participants payable from plan assets is expected to be as follows: 2022 - $2,580,000, 2023 - $1,712,000, 2024 - $1,640,000, 2025 - $1,577,000 and 2026 - $1,539,000 and an aggregate of $6,674,000 is expected to be paid in the fiscal five-year period 2027 through 2031.
Number of common stock issued to directors for settlement of deferred stock units			12,411
Cash paid to directors in lieu of issuance of deferred common share units				$ 20,000
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets						7.75%	7.75%
Defined Benefit Plan, Expected Amortization of Gain (Loss), Next Fiscal Year						$ 392,000
Defined Benefit Plan, Expected Amortization of Transition Asset (Obligation), Next Fiscal Year						0
Defined Benefit Plan, Expected Amortization of Prior Service Cost (Credit), Next Fiscal Year						0
Defined Benefit Plan, Benefit Obligation						21,578,000	$ 23,274,000	$ 30,304,000
Defined Benefit Plan, Plan Assets, Amount						21,102,000	18,260,000	$ 23,903,000
Defined Benefit Pension Plan, Liabilities						476,000	5,014,000
Deferred Compensation Arrangement with Individual, Allocated Share-based Compensation Expense						30,000	33,000
Defined Benefit Plan, Plan Assets, Contributions by Employer						1,847,000	3,600,000
Simple Internal Revenue Code, Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer						36,000	14,000
Defined Contribution Plan, Employer Discretionary Contribution Amount						$ 5,000
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent						3.00%
Board of Directors Chairman [Member]
Defined Benefit Plan Disclosure [Line Items]
Non Cash Director Fee Compensation						$ 90,000	100,000
Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets					7.75%
Equity Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Share-based Compensation, Total						78,000	$ 113,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total						$ 34,000
2016 Equity Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period						500,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number						372,000
2016 Equity Plan [Member] | Board of Directors Chairman [Member]
Defined Benefit Plan Disclosure [Line Items]
Shares Issued, Price Per Share	$ 8.54	$ 5.98
Non Cash Director Compensation	$ 30,000.00	$ 25,000
Stock Issued During Period, Shares, Restricted Stock Award, Gross	10,536	16,720
Weighted Average [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate						2.48%	2.29%
PBGC [Member]
Defined Benefit Plan Disclosure [Line Items]
Payment for Pension Benefits						$ 1,847,000
PBGC [Member] | Equity Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Payment for Pension Benefits							$ 3,600,000