Securities (Summary of Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Available for sale securities amortized cost	$ 881,570	$ 895,273
Available for sale securities unrealized gains	15,570	9,117
Available for sale securities unrealized losses	(2,569)	(4,900)
Available for sale debt securities	894,571	899,490
Available for sale securities amortized cost	881,570
Allowance for credit losses on securities	0
Obligations of U.S. government-sponsored enterprises [Member]
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Available for sale securities amortized cost	131,186	157,255
Available for sale securities unrealized gains	628	626
Available for sale securities unrealized losses	(145)	(233)
Available for sale debt securities	131,669	157,648
Allowance for credit losses on securities	0
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 Maturity Securities [Line Items]
Available for sale securities amortized cost	725,890	713,553
Available for sale securities unrealized gains	14,942	8,491
Available for sale securities unrealized losses	(527)	(2,964)
Available for sale debt securities	740,305	719,080
Allowance for credit losses on securities	0
Individual name issuer trust preferred debt securities [Member]
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Available for sale securities amortized cost	13,341	13,324
Available for sale securities unrealized gains	0	0
Available for sale securities unrealized losses	(672)	(745)
Available for sale debt securities	12,669	12,579
Allowance for credit losses on securities	0
Corporate bonds [Member]
Schedule of Available for Sale and Held to Maturity Securities [Line Items]
Available for sale securities amortized cost	11,153	11,141
Available for sale securities unrealized gains	0	0
Available for sale securities unrealized losses	(1,225)	(958)
Available for sale debt securities	9,928	$ 10,183
Allowance for credit losses on securities	$ 0

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

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Amortized cost of 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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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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