Investment Securities - Fair Value of Investments with Sustained Gross Unrealized Losses (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Less than 12 months, Fair Value	$ 56,499,000	$ 93,924,000
Available-for-sale, Less than 12 months, Unrealized Losses	(483,000)	(398,000)
Available-for-sale, 12 months or longer, Fair Value	4,991,000	21,235,000
Available-for-sale, 12 months or longer, Unrealized losses	0	(191,000)
Available-for-sale, Total Fair Value	61,490,000	115,159,000
Available-for-sale, Total Unrealized Losses	(483,000)	(589,000)
U.S. Treasury Securities and Obligations of U.S. Government Corporations & Agencies
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Less than 12 months, Fair Value	20,000,000	23,375,000
Available-for-sale, Less than 12 months, Unrealized Losses	(135,000)	(60,000)
Available-for-sale, 12 months or longer, Fair Value	0	0
Available-for-sale, 12 months or longer, Unrealized losses	0	0
Available-for-sale, Total Fair Value	20,000,000	23,375,000
Available-for-sale, Total Unrealized Losses	(135,000)	(60,000)
Held-to-maturity, [Abstract]
Held-to-maturity, Less than 12 months, Fair Value		14,996,000
Held-to-maturity, Less than 12 months, Unrealized Losses		(25,000)
Held-to-maturity, 12 months or longer, Fair Value		24,565,000
Held-to-maturity, 12 months or longer, Unrealized losses		(44,000)
Held-to-maturity,Total Fair Value		39,561,000
Held-to-maturity, Total Unrealized Losses		(69,000)
Obligations of States and Political Subdivisions
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Less than 12 months, Fair Value	27,300,000	3,469,000
Available-for-sale, Less than 12 months, Unrealized Losses	(335,000)	(16,000)
Available-for-sale, 12 months or longer, Fair Value	0	347,000
Available-for-sale, 12 months or longer, Unrealized losses	0	(1,000)
Available-for-sale, Total Fair Value	27,300,000	3,816,000
Available-for-sale, Total Unrealized Losses	(335,000)	(17,000)
Held-to-maturity, [Abstract]
Held-to-maturity, 12 months or longer, Fair Value		347,000
Held-to-maturity, 12 months or longer, Unrealized losses		(1,000)
Mortgage-backed Securities: GSE Residential
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Less than 12 months, Fair Value	5,199,000	67,080,000
Available-for-sale, Less than 12 months, Unrealized Losses	(8,000)	(322,000)
Available-for-sale, 12 months or longer, Fair Value	4,991,000	20,888,000
Available-for-sale, 12 months or longer, Unrealized losses	0	(190,000)
Available-for-sale, Total Fair Value	10,190,000	87,968,000
Available-for-sale, Total Unrealized Losses	(8,000)	$ (512,000)
Other Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Less than 12 months, Fair Value	4,000,000
Available-for-sale, Less than 12 months, Unrealized Losses	(5,000)
Available-for-sale, 12 months or longer, Fair Value	0
Available-for-sale, 12 months or longer, Unrealized losses	0
Available-for-sale, Total Fair Value	4,000,000
Available-for-sale, Total Unrealized Losses	$ (5,000)

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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