REGULATORY CAPITAL (Details)		Sep. 30, 2021	Sep. 30, 2020
Magyar Bancorp, Inc. [Member]
Tier 1 leverage ratio
Tier 1 leverage ratio (to average assets) ratio		12.43%	7.84%
Common Equity Tier 1 Capital (to risk-weighted assets) ratio		19.19%	11.84%
Tier 1 risk-based capital ratio
Tier 1 risk-based capital ratio (to risk-weighted assets) ratio		19.19%	11.84%
Total risk-based capital ratio
Total risk-based capital ratio (to risk-weighted assets) ratio		20.44%	13.09%
Magyar Bank [Member]
Tier 1 leverage ratio
Tier 1 leverage ratio (to average assets) ratio		10.18%	8.30%
Required amount of Tier 1 Capital for adequacy purposes effective, ratio		4.00%	4.00%
Minimum Tier 1 Capital required to be well-capitalized, ratio		5.00%	5.00%
Common Equity Tier 1 Capital (to risk-weighted assets) ratio		15.74%	11.93%
Required amount of common equity Tier 1 Capital for adequacy purposes effective, ratio	[1]	7.00%	7.00%
Minimum common equity Tier 1 Capital required to be well-capitalized, ratio		6.50%	6.50%
Tier 1 risk-based capital ratio
Tier 1 risk-based capital ratio (to risk-weighted assets) ratio		15.74%	11.93%
Required amount of Tier 1 Capital for adequacy purposes effective, ratio	[1]	8.50%	8.50%
Minimum Tier 1 Capital required to be well-capitalized, ratio		8.00%	8.00%
Total risk-based capital ratio
Total risk-based capital ratio (to risk-weighted assets) ratio		16.99%	13.18%
Required amount of capital for adequacy purposes effective, ratio	[1]	10.50%	10.50%
Minimum Capital required to be well-capitalized, ratio		10.00%	10.00%

[1] Includes 2.50% capital conservation buffer