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Investment Securities - Non-marketable Securities (Details)		1 Months Ended	12 Months Ended
	Nov. 27, 2018	Oct. 31, 2018 USD ($) shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) shares	Feb. 20, 2020
Marketable Securities [Line Items]
Federal Home Loan Bank stock, par value (usd per share) | $ / shares			$ 100
Stock split ratio	2
Investments in low income housing tax credit funds			$ 4,100,000	$ 4,600,000
Low income housing tax credits and other tax benefits			603,000
Low income housing amortization expense			515,000
Unfunded commitments for low income housing tax credit funds			2,200,000
Other assets
Marketable Securities [Line Items]
Federal Home Loan Bank stock			$ 11,700,000	$ 11,100,000
Visa Inc. Class B Common Stock
Marketable Securities [Line Items]
Number of shares of securities carried at cost (in shares) | shares			10,439	10,439
Fair value of Class B common stock			$ 0	$ 0
Equity securities			$ 3,200,000	$ 2,200,000
Shares of Visa Inc. Class B restricted common stock (in shares) | shares		6,500
Gain from sale of Visa Inc. Class B restricted common stock		$ 956,000
Visa Inc. | Visa Inc. Class B common stock
Marketable Securities [Line Items]
Stock split ratio			1.6228	1.6298
Subsequent event
Marketable Securities [Line Items]
Federal Home Loan Bank, dividend rate percentage					7.00%

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