Investment Securities - Fair Value to Amortized Cost (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Securities available for sale:
Amortized Cost	$ 193,750	$ 187,778
Gross Unrealized Gain	12,236	14,259
Gross Unrealized Losses	612	72
Fair Value	205,374	201,965
Securities held to maturity:
Amortized Cost	1,957	2,102
Gross Unrealized Gain	262	283
Gross Unrealized Losses		0
Fair Value	2,219	2,385
U.S. agency bonds and notes
Securities available for sale:
Amortized Cost	500
Fair Value	500
Agency mortgage-backed
Securities available for sale:
Amortized Cost	9,374	7,499
Gross Unrealized Gain	380	453
Gross Unrealized Losses	105	0
Fair Value	9,649	7,952
Securities held to maturity:
Amortized Cost	73	82
Gross Unrealized Gain	6	7
Gross Unrealized Losses		0
Fair Value	79	89
Agency CMO
Securities available for sale:
Amortized Cost	8,965	9,398
Gross Unrealized Gain	219	407
Gross Unrealized Losses	39	0
Fair Value	9,145	9,805
Privately-issued CMO
Securities available for sale:
Amortized Cost	776	886
Gross Unrealized Gain	89	80
Gross Unrealized Losses	7	8
Fair Value	858	958
Privately-issued ABS
Securities available for sale:
Amortized Cost	794	884
Gross Unrealized Gain	67	81
Gross Unrealized Losses	1	5
Fair Value	860	960
SBA certificates
Securities available for sale:
Amortized Cost	2,355	639
Gross Unrealized Gain	4	58
Gross Unrealized Losses	26	3
Fair Value	2,333	694
Municipal bonds
Securities available for sale:
Amortized Cost	170,986	168,472
Gross Unrealized Gain	11,477	13,180
Gross Unrealized Losses	434	56
Fair Value	182,029	181,596
Securities held to maturity:
Amortized Cost	1,884	2,020
Gross Unrealized Gain	256	276
Gross Unrealized Losses		0
Fair Value	$ 2,140	$ 2,296

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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