LOANS RECEIVABLE - Summary of classes of loan portfolio in which formal risk weighting system is utilized (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Sep. 30, 2021
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 642,487	$ 707,623
One-to-four family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans	183,080	202,330
Multi-family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans	80,391	76,122
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	141,474	165,992
Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	174,970	205,413
Commercial business
Financing Receivable, Recorded Investment [Line Items]
Total Loans	62,011	57,236
Risk Rating System
Financing Receivable, Recorded Investment [Line Items]
Total Loans	641,926	707,093
Risk Rating System \| One-to-four family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans	183,080	202,330
Risk Rating System \| Multi-family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans	80,391	76,122
Risk Rating System \| Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	141,474	165,992
Risk Rating System \| Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	174,970	205,413
Risk Rating System \| Commercial business
Financing Receivable, Recorded Investment [Line Items]
Total Loans	62,011	57,236
Risk Rating System \| Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans	634,366
Risk Rating System \| Pass \| One-to-four family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans	179,502
Risk Rating System \| Pass \| Multi-family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans	80,391
Risk Rating System \| Pass \| Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	139,455
Risk Rating System \| Pass \| Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	173,007
Risk Rating System \| Pass \| Commercial business
Financing Receivable, Recorded Investment [Line Items]
Total Loans	62,011
Risk Rating System \| Special Pass
Financing Receivable, Recorded Investment [Line Items]
Total Loans		690,630
Risk Rating System \| Special Pass \| One-to-four family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans		197,920
Risk Rating System \| Special Pass \| Multi-family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans		71,497
Risk Rating System \| Special Pass \| Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans		162,657
Risk Rating System \| Special Pass \| Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans		201,320
Risk Rating System \| Special Pass \| Commercial business
Financing Receivable, Recorded Investment [Line Items]
Total Loans		57,236
Risk Rating System \| Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans	3,225
Risk Rating System \| Special Mention \| One-to-four family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans	1,206
Risk Rating System \| Special Mention \| Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,019
Risk Rating System \| Total Mention
Financing Receivable, Recorded Investment [Line Items]
Total Loans		8,084
Risk Rating System \| Total Mention \| One-to-four family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans		1,404
Risk Rating System \| Total Mention \| Multi-family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans		4,625
Risk Rating System \| Total Mention \| Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans		2,055
Risk Rating System \| Total Mention \| Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans		0
Risk Rating System \| Total Mention \| Commercial business
Financing Receivable, Recorded Investment [Line Items]
Total Loans		0
Risk Rating System \| Substandard
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,335	8,379
Risk Rating System \| Substandard \| One-to-four family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,372	3,006
Risk Rating System \| Substandard \| Multi-family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans		0
Risk Rating System \| Substandard \| Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans		1,280
Risk Rating System \| Substandard \| Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 1,963	4,093
Risk Rating System \| Substandard \| Commercial business
Financing Receivable, Recorded Investment [Line Items]
Total Loans		0
Risk Rating System \| Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total Loans		0
Risk Rating System \| Doubtful \| One-to-four family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans		0
Risk Rating System \| Doubtful \| Multi-family residential
Financing Receivable, Recorded Investment [Line Items]
Total Loans		0
Risk Rating System \| Doubtful \| Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Total Loans		0
Risk Rating System \| Doubtful \| Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Total Loans		0
Risk Rating System \| Doubtful \| Commercial business
Financing Receivable, Recorded Investment [Line Items]
Total Loans		$ 0

PRUDENTIAL BANCORP, INC. 10-Q