Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		3 Months Ended
		Dec. 31, 2019		Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		$ 171,067	[1]	$ 124,657
Balance at end of period		175,653		156,905
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	[2]	50		(129)
Other comprehensive income (loss)	[2]	(196)		(79)
Balance at end of period	[2]	(146)		(145)
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]	90		(58)
Other comprehensive income (loss)	[2]	(206)		(86)
Balance at end of period	[2]	(116)		(81)
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]	(40)		(71)
Other comprehensive income (loss)	[2]	10		7
Balance at end of period	[2]	$ (30)		(64)
Accounting Standards Update 2016-01 | Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss)				63
Accounting Standards Update 2016-01 | Accumulated Net Unrealized Investment Gain (Loss) | Available-for-sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss)				63
Accounting Standards Update 2016-01 | Accumulated Net Unrealized Investment Gain (Loss) | Held-to-maturity Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss)				$ 0

[1] Derived from audited consolidated financial statements.

[2] All amounts are net of income taxes.