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Investment Securities - Available-for-Sale Securities Amortized Cost and Fair Value (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 373,038,000	$ 423,923,000
Gross Unrealized Gains	19,393,000	8,748,000
Gross Unrealized (Losses)	(80,000)	(411,000)
Allowance for Credit Losses	0	0
Securities available for sale, Fair Value	392,351,000	432,260,000
Other assets
Debt Securities, Available-for-sale [Line Items]
Accrued interest	1,900,000	1,800,000
MBS pass-through securities issued by FHLMC and FNMA
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	50,686,000	98,502,000
Gross Unrealized Gains	2,530,000	1,617,000
Gross Unrealized (Losses)	0	(48,000)
Allowance for Credit Losses	0	0
Securities available for sale, Fair Value	53,216,000	100,071,000
CMOs issued by FHLMC
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	143,267,000	139,398,000
Gross Unrealized Gains	7,925,000	3,892,000
Gross Unrealized (Losses)	(1,000)	(64,000)
Allowance for Credit Losses	0	0
Securities available for sale, Fair Value	151,191,000	143,226,000
CMOs issued by FNMA
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	16,450,000	22,702,000
Gross Unrealized Gains	580,000	390,000
Gross Unrealized (Losses)	0	0
Allowance for Credit Losses	0	0
Securities available for sale, Fair Value	17,030,000	23,092,000
CMOs issued by GNMA
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	6,863,000	11,719,000
Gross Unrealized Gains	351,000	42,000
Gross Unrealized (Losses)	0	(6,000)
Allowance for Credit Losses	0	0
Securities available for sale, Fair Value	7,214,000	11,755,000
SBA-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	30,941,000	35,674,000
Gross Unrealized Gains	1,976,000	688,000
Gross Unrealized (Losses)	(55,000)	(76,000)
Allowance for Credit Losses	0	0
Securities available for sale, Fair Value	32,862,000	36,286,000
Debentures of government sponsored agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	19,944,000	48,389,000
Gross Unrealized Gains	266,000	727,000
Gross Unrealized (Losses)	(24,000)	(70,000)
Allowance for Credit Losses	0	0
Securities available for sale, Fair Value	20,186,000	49,046,000
Obligations of state and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	104,887,000	66,042,000
Gross Unrealized Gains	5,765,000	1,386,000
Gross Unrealized (Losses)	0	(146,000)
Allowance for Credit Losses	0	0
Securities available for sale, Fair Value	$ 110,652,000	67,282,000
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		1,497,000
Gross Unrealized Gains		6,000
Gross Unrealized (Losses)		(1,000)
Allowance for Credit Losses		0
Securities available for sale, Fair Value		$ 1,502,000

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