Securities, HTM Securities in Continuous Unrealized Loss Position (Details) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2021 USD ($) Position	Dec. 31, 2020 USD ($) Position
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 172,786	$ 103,147
12 months or longer	0	0
Total	172,786	103,147
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(8,316)	(1,675)
12 months or longer	0	0
Total	$ (8,316)	$ (1,675)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months \| Position	61	9
12 months or longer \| Position	0	0
Total \| Position	61	9
Held-to-maturity, past due	$ 0	$ 0
Accrued interest reversed against interest income	0	0
Collateral-dependent HTM debt securities	0	0
AIR on HTM debt securities	2,700	2,700
Federal Agency [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	94,159	98,342
12 months or longer	0	0
Total	94,159	98,342
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(5,841)	(1,658)
12 months or longer	0	0
Total	$ (5,841)	$ (1,658)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months \| Position	4	4
12 months or longer \| Position	0	0
Total \| Position	4	4
Mortgage-Backed [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 8,312
12 months or longer	0
Total	8,312
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(108)
12 months or longer	0
Total	$ (108)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months \| Position	1
12 months or longer \| Position	0
Total \| Position	1
State & Municipal [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	$ 70,315	$ 4,805
12 months or longer	0	0
Total	70,315	4,805
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(2,367)	(17)
12 months or longer	0	0
Total	$ (2,367)	$ (17)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months \| Position	56	5
12 months or longer \| Position	0	0
Total \| Position	56	5
US Government Agencies Debt Securities and US Government-sponsored Enterprises Debt Securities [Member]
Unrealized Loss Position, Number of Positions [Abstract]
Held-to-maturity debt securities, percentage	59.00%	65.00%

Amount of reversed for accrued interest receivable on the HTM debt securities during the period.

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Amount of held-to-maturity securities that are collateral dependent.

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Number of investment positions in held-to-maturity investments in a continuous unrealized loss position for greater than or equal to a year for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

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Number of investment positions in held-to-maturity investments in a continuous unrealized loss position for less than one year or normal operating cycle, if longer, for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

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Percentage of investment in debt security measured at amortized cost (held-to-maturity).

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Amount, after allowance for credit loss, of accrued interest on investment in debt security measured at amortized cost (held-to-maturity).

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Amount of investment in debt security measured at amortized cost (held-to-maturity), past due.

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for less than 12 months.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for 12 months or longer.

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Disclosure regarding factors used to determine that the impairment of securities categorized as held-to-maturity where cost exceeds fair value is not an other than temporary impairment (OTTI). This item contains disclosure of the number of investment positions in the held-to-maturity investments determined to be temporarily impaired.

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