Investment and Mortgage-Backed Securities, Available for Sale (Narrative) (Details)	Mar. 31, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 587,696,255	$ 604,157,308
Fair Value	$ 541,070,073	$ 550,148,284
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions | security	411	416
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | security	339	211
Asset Pledged as Collateral
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 374,300,000	$ 318,000,000
Fair Value	348,300,000	297,000,000
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	61,300,000	60,100,000
Fair Value	$ 54,800,000	$ 53,800,000