Investment and Mortgage-Backed Securities, Available for Sale (Schedule of Available for Sale Securities) (Details) - USD ($)	9 Months Ended	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Gross Realized Losses	$ 67,000	$ 162,000
Available For Sale Securities Pledged as Collateral, Amortized Cost Basis	118,900,000		$ 99,200,000
Pledged Assets Separately Reported, Other Debt Securities Available-for-sale or Held-for-investment	118,000,000		100,500,000
Amortized Cost of Investment And Mortgage-Backed Securities Available For Sale	376,910,106		380,374,568
Available-for-sale Securities, Gross Unrealized Gains	1,969,797		5,840,528
Available-for-sale Securities, Gross Unrealized Losses	5,127,610		1,241,190
Available-for-sale Securities, Fair Value Disclosure	373,752,293		384,973,906
Proceeds From Sale of Available For Sale Securities Including Mortgage Backed Securities	28,600,000	46,800,000
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost of Investment And Mortgage-Backed Securities Available For Sale	60,381,306		59,623,185
Available-for-sale Securities, Gross Unrealized Gains	897,641		2,789,233
Available-for-sale Securities, Gross Unrealized Losses	797,693		56,851
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost of Investment And Mortgage-Backed Securities Available For Sale	29,900,000		26,900,000
Available-for-sale Securities, Fair Value Disclosure	29,800,000
Investments [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Gross Realized Gains	503,000	$ 870,000	1,288
Collateralized Loan Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost of Investment And Mortgage-Backed Securities Available For Sale	12,957,559		8,522,043
Available-for-sale Securities, Gross Unrealized Losses	9,096		1,546
Available-for-sale Securities, Gross Realized Gains	33,076
SBA Bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost of Investment And Mortgage-Backed Securities Available For Sale	118,275,224		123,324,802
Available-for-sale Securities, Gross Unrealized Gains	227,093		1,113,160
Available-for-sale Securities, Gross Unrealized Losses	1,277,257		189,518
Mortgage-Backed Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost of Investment And Mortgage-Backed Securities Available For Sale	182,045,631		186,732,705
Available-for-sale Securities, Gross Unrealized Gains	811,987		1,936,847
Available-for-sale Securities, Gross Unrealized Losses	2,977,163		973,572
State Tax Credit investment [Domain]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost of Investment And Mortgage-Backed Securities Available For Sale	88,350
Equity Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost of Investment And Mortgage-Backed Securities Available For Sale	155,000		155,000
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	0		0
Taxable Municipal Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost of Investment And Mortgage-Backed Securities Available For Sale	3,007,036		2,016,833
Available-for-sale Securities, Gross Unrealized Gains	0		0
Available-for-sale Securities, Gross Unrealized Losses	66,401		19,703
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Fair Value Disclosure	60,481,254		62,355,567
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Collateralized Loan Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Fair Value Disclosure	12,981,539		8,521,785
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| SBA Bonds
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Fair Value Disclosure	117,225,060		124,248,444
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Mortgage-Backed Securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Fair Value Disclosure	179,880,455		187,695,980
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| State Tax Credit investment [Domain]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Fair Value Disclosure	88,350		0
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Equity Securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Fair Value Disclosure	155,000		155,000
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Taxable Municipal Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Fair Value Disclosure	$ 2,940,635		$ 1,997,130

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Proceeds From Sale of Available For Sale Securities Including Mortgage Backed Securities

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount of unrealized gain before deducting unrealized loss on investments in debt and equity securities classified as available-for-sale securities.

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The fair value, as of the date of each statement of financial position presented, of other securities, classified as available for sale or held for investment, which are owned but transferred to serve as collateral for the payment of the related debt obligation, primarily a secured borrowing or repurchase agreement, and that are reclassified and separately reported in the statement of financial position because the transferee has the right by contract or custom to sell or re-pledge them.

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