Stockholders' Equity - Summary of Bank's Regulatory Capital Levels (Details) $ in Thousands	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)
Actual Amount
Total capital (to risk-weighted assets)	$ 743,741	$ 770,621
Tier 1 capital (to risk-weighted assets)	706,764	734,987
Common equity tier 1 capital (to risk-weighted assets)	706,764	734,987
Tier 1 capital (to adjusted total assets)	$ 706,764	$ 734,987
Actual Ratio
Total capital (to risk-weighted assets)	0.1557	0.1475
Tier 1 capital (to risk-weighted assets)	0.1479	0.1407
Common equity tier 1 capital (to risk-weighted assets)	0.1479	0.1407
Tier 1 capital (to adjusted total assets)	0.0915	0.0907
For Capital Adequacy Purposes Amount
Total capital (to risk-weighted assets)	$ 382,247	$ 418,015
Tier 1 capital (to risk-weighted assets)	286,685	313,511
Common equity tier 1 capital (to risk-weighted assets)	215,014	235,133
Tier 1 capital (to adjusted total assets)	$ 309,031	$ 324,170
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)	$ 688,597	$ 695,417
Tier 1 capital (to risk-weighted assets)	651,620	659,783
Common equity tier 1 capital (to risk-weighted assets)	651,620	659,783
Tier 1 capital (to adjusted total assets)	$ 651,620	$ 659,783
Actual Ratio
Total capital (to risk-weighted assets)	0.1442	0.1331
Tier 1 capital (to risk-weighted assets)	0.1365	0.1263
Common equity tier 1 capital (to risk-weighted assets)	0.1365	0.1263
Tier 1 capital (to adjusted total assets)	0.0844	0.0815
For Capital Adequacy Purposes Amount
Total capital (to risk-weighted assets)	$ 382,034	$ 417,853
Tier 1 capital (to risk-weighted assets)	286,525	313,389
Common equity tier 1 capital (to risk-weighted assets)	214,894	235,042
Tier 1 capital (to adjusted total assets)	$ 308,656	$ 323,922
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)	$ 477,542	$ 522,316
Tier 1 capital (to risk-weighted assets)	382,034	417,853
Common equity tier 1 capital (to risk-weighted assets)	310,402	339,505
Tier 1 capital (to adjusted total assets)	$ 385,820	$ 404,902
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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