Stockholders' Equity - Summary of Bank's Regulatory Capital Levels (Details) $ in Thousands	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)
Actual Amount
Total capital (to risk-weighted assets)	$ 770,621	$ 778,253
Tier 1 capital (to risk-weighted assets)	734,987	748,315
Common equity tier 1 capital (to risk-weighted assets)	734,987	748,315
Tier 1 capital (to adjusted total assets)	$ 734,987	$ 748,315
Actual Ratio
Total capital (to risk-weighted assets)	0.1475	0.1517
Tier 1 capital (to risk-weighted assets)	0.1407	0.1458
Common equity tier 1 capital (to risk-weighted assets)	0.1407	0.1458
Tier 1 capital (to adjusted total assets)	0.0907	0.1014
For Capital Adequacy Purposes Amount
Total capital (to risk-weighted assets)	$ 418,015	$ 410,515
Tier 1 capital (to risk-weighted assets)	313,511	307,886
Common equity tier 1 capital (to risk-weighted assets)	235,133	230,914
Tier 1 capital (to adjusted total assets)	$ 324,170	$ 295,290
For Capital Adequacy Purposes Ratio
Total capital (to risk-weighted assets)	0.0800	0.0800
Tier 1 capital (to risk-weighted assets)	0.0600	0.0600
Common equity tier 1 capital (to risk-weighted assets)	0.0450	0.0450
Tier 1 capital (to adjusted total assets)	0.0400	0.0400
Kearny Federal Savings Bank
Actual Amount
Total capital (to risk-weighted assets)	$ 695,417	$ 672,274
Tier 1 capital (to risk-weighted assets)	659,783	642,336
Common equity tier 1 capital (to risk-weighted assets)	659,783	642,336
Tier 1 capital (to adjusted total assets)	$ 659,783	$ 642,336
Actual Ratio
Total capital (to risk-weighted assets)	0.1331	0.1310
Tier 1 capital (to risk-weighted assets)	0.1263	0.1252
Common equity tier 1 capital (to risk-weighted assets)	0.1263	0.1252
Tier 1 capital (to adjusted total assets)	0.0815	0.0870
For Capital Adequacy Purposes Amount
Total capital (to risk-weighted assets)	$ 417,853	$ 410,429
Tier 1 capital (to risk-weighted assets)	313,389	307,822
Common equity tier 1 capital (to risk-weighted assets)	235,042	230,866
Tier 1 capital (to adjusted total assets)	$ 323,922	$ 295,163
For Capital Adequacy Purposes Ratio
Total capital (to risk-weighted assets)	0.0800	0.0800
Tier 1 capital (to risk-weighted assets)	0.0600	0.0600
Common equity tier 1 capital (to risk-weighted assets)	0.0450	0.0450
Tier 1 capital (to adjusted total assets)	0.0400	0.0400
To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount
Total capital (to risk-weighted assets)	$ 522,316	$ 513,036
Tier 1 capital (to risk-weighted assets)	417,853	410,429
Common equity tier 1 capital (to risk-weighted assets)	339,505	333,473
Tier 1 capital (to adjusted total assets)	$ 404,902	$ 368,954
To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio
Total capital (to risk-weighted assets)	0.1000	0.1000
Tier 1 capital (to risk-weighted assets)	0.0800	0.0800
Common equity tier 1 capital (to risk-weighted assets)	0.0650	0.0650
Tier 1 capital (to adjusted total assets)	5.00%	5.00%

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
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-Paragraph 1
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