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Investment Securities - Narrative (Details) $ in Thousands	Mar. 31, 2021 USD ($) instrument	Dec. 31, 2020 USD ($)
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Accrued interest on investment securities	$ 20,600
Allowance for credit losses	245	$ 0
Gross unrealized losses	19,186	349
Carrying value of securities pledged as collateral	999,200	890,000
Securities sold under repurchase agreements	178,200	167,300
State and municipal
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Allowance for credit losses	245	0
Gross unrealized losses	$ 2,654	246
Number of securities in unrealized loss positions | instrument	108
U.S. Government-sponsored mortgage-backed securities
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Allowance for credit losses	$ 0	0
Gross unrealized losses	$ 16,347	103
Number of securities in unrealized loss positions | instrument	55
U.S. Government-sponsored agency securities
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Allowance for credit losses	$ 0	0
Gross unrealized losses	$ 163	0
Number of securities in unrealized loss positions | instrument	2
Corporate obligations
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross unrealized losses	$ 22	$ 0
Number of securities in unrealized loss positions | instrument	1

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Debt Securities, Available-for-sale and Held-to-maturity, Accrued Interest

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Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of allowance for credit loss for debt security measured at amortized cost (held-to-maturity).

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Amount of asset associated with funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price.

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