Employee Benefits - Narrative (Details)			3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	Jul. 14, 2021	Jan. 01, 2012	Sep. 30, 2021 USD ($) shares	Sep. 30, 2020 USD ($)	Dec. 31, 2012 USD ($) $ / shares shares	Sep. 30, 2021 USD ($) shares	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) shares
Compensation and Retirement Disclosure [Abstract]
Number of hours of service required for participation in ESOP, per first 12 month period (in hours)		1000 hours
Vesting percentage after requisite service period is met (as a percent)		100.00%
Requisite service period (in years)		2 years
Employee stock ownership plan (ESOP), requisite service period (in hours)		1000 hours
Employee Stock Ownership Plan (ESOP), Debt Structure, Employer Loan, Amount					$ 2,600,000
Employee stock ownership plan shares purchased | shares					518,420
Shares acquired (in shares) | shares			479,330			479,330		479,330
Employee stock ownership plan (ESOP), weighted average purchase price of shares purchased (in dollars per share) | $ / shares					$ 5.09
Amortization period of ESOP loan					10 years
Employee stock ownership plan (ESOP), debt structure, employer loan, interest rate					2.30%
Employee stock ownership plan (ESOP), periodic installment payments from esop, amount paid								$ 282,000
Employee stock ownership plan (ESOP), interest payments from esop								$ 13,000
ESOP compensation expense for allocated shares			$ 439,000	$ 251,000		$ 1,335,000	$ 756,000
Stock split, conversion ratio	2