Securities (Summary of Investments) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Available for Sale and Held to Maturty Securities [Line Items]
Available for sale debt securities amortized cost basis	$ 952,618	$ 881,570
Available for sale debt securities unrealized gains	11,859	15,570
Available for sale debt securities unrealized losses	(16,383)	(2,569)
Available for sale debt securities allowance for credit losses	0	0
Available for sale debt securities, at fair value	948,094	894,571
Obligations of U.S. government-sponsored enterprises [Member]
Schedule of Available for Sale and Held to Maturty Securities [Line Items]
Available for sale debt securities amortized cost basis	186,193	131,186
Available for sale debt securities unrealized gains	380	628
Available for sale debt securities unrealized losses	(4,622)	(145)
Available for sale debt securities allowance for credit losses	0	0
Available for sale debt securities, at fair value	181,951	131,669
Mortgage-backed securities issued by U.S. government-sponsored agencies and U.S. government-sponsored enterprises [Member]
Schedule of Available for Sale and Held to Maturty Securities [Line Items]
Available for sale debt securities amortized cost basis	741,924	725,890
Available for sale debt securities unrealized gains	11,479	14,942
Available for sale debt securities unrealized losses	(10,416)	(527)
Available for sale debt securities allowance for credit losses	0	0
Available for sale debt securities, at fair value	742,987	740,305
Individual name issuer trust preferred debt securities
Schedule of Available for Sale and Held to Maturty Securities [Line Items]
Available for sale debt securities amortized cost basis	13,345	13,341
Available for sale debt securities unrealized gains	0	0
Available for sale debt securities unrealized losses	(437)	(672)
Available for sale debt securities allowance for credit losses	0	0
Available for sale debt securities, at fair value	12,908	12,669
Corporate bonds [Member]
Schedule of Available for Sale and Held to Maturty Securities [Line Items]
Available for sale debt securities amortized cost basis	11,156	11,153
Available for sale debt securities unrealized gains	0	0
Available for sale debt securities unrealized losses	(908)	(1,225)
Available for sale debt securities allowance for credit losses	0	0
Available for sale debt securities, at fair value	$ 10,248	$ 9,928

Line items for schedule of Available for Sale and Held to Maturty Securities.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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