SECURITIES - Held to Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Sep. 30, 2018
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Gross unrealized gains	$ 0	$ 0
Gross unrealized (losses)	(5,434)	(11,180)
Securities held to maturity	149,164	160,563
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
LESS THAN 12 MONTHS, Fair Value	0	5,767
LESS THAN 12 MONTHS, Unrealized (Losses)	0	(287)
OVER 12 MONTHS, Fair Value	149,164	154,796
OVER 12 MONTHS, Unrealized (Losses)	(5,435)	(10,893)
TOTAL, Fair Value	149,164	160,563
TOTAL, Unrealized (Losses)	(5,435)	(11,180)
AMORTIZED COST
Due after ten years	146,992	163,893
Total	146,992	163,893
Mortgage-backed securities	7,606	7,850
Total held to maturity securities at cost	154,598	171,743
FAIR VALUE
Due after ten years	141,768	153,135
Total	141,768	153,135
Mortgage-backed securities	7,396	7,428
Total held to maturity securities	149,164	160,563
Non-bank Qualified Obligations of States and Political Subdivisions
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Gross unrealized gains	0	0
Gross unrealized (losses)	(5,224)	(10,758)
Securities held to maturity	141,768	153,135
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
LESS THAN 12 MONTHS, Fair Value	0	5,767
LESS THAN 12 MONTHS, Unrealized (Losses)	0	(287)
OVER 12 MONTHS, Fair Value	141,768	147,368
OVER 12 MONTHS, Unrealized (Losses)	(5,225)	(10,471)
TOTAL, Fair Value	141,768	153,135
TOTAL, Unrealized (Losses)	(5,225)	(10,758)
AMORTIZED COST
Total held to maturity securities at cost	146,992	163,893
FAIR VALUE
Total held to maturity securities	141,768	153,135
Mortgage-backed Securities
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Gross unrealized gains	0	0
Gross unrealized (losses)	(210)	(422)
Securities held to maturity	7,396	7,428
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
LESS THAN 12 MONTHS, Fair Value	0	0
LESS THAN 12 MONTHS, Unrealized (Losses)	0	0
OVER 12 MONTHS, Fair Value	7,396	7,428
OVER 12 MONTHS, Unrealized (Losses)	(210)	(422)
TOTAL, Fair Value	7,396	7,428
TOTAL, Unrealized (Losses)	(210)	(422)
AMORTIZED COST
Total held to maturity securities at cost	7,606	7,850
FAIR VALUE
Total held to maturity securities	$ 7,396	$ 7,428

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