Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023		Mar. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		$ 223,549	$ 210,375	$ 218,569	[1]	$ 206,899
Balance at end of period		227,661	212,269	227,661		212,269
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	[2]	(735)	42	(717)		59
Other comprehensive income	[2]	240	(149)	222		(166)
Balance at end of period	[2]	(495)	(107)	(495)		(107)
Accumulated Net Unrealized Investment Gain (Loss) | Available-for-sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	[2]	(725)	57	(706)		75
Other comprehensive income	[2]	239	(152)	220		(170)
Balance at end of period	[2]	(486)	(95)	(486)		(95)
Accumulated Net Unrealized Investment Gain (Loss) | Held-to-maturity Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	[2]	(10)	(15)	(11)		(16)
Other comprehensive income	[2]	1	3	2		4
Balance at end of period	[2]	$ (9)	$ (12)	$ (9)		$ (12)

[1] Derived from audited consolidated financial statements.

[2] All amounts are net of income taxes.