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Investment Securities (Narrative) (Details) | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2021 USD ($) Security | Jun. 30, 2020 USD ($) | Jun. 30, 2021 USD ($) Security | Jun. 30, 2020 USD ($) | Dec. 31, 2020 USD ($) Security
Schedule Of Investments [Line Items] |  |  |  |  |
Securities pledged as collateral | $ 715,300,000 |  | $ 715,300,000 |  | $ 567,400,000
Number of security positions, unrealized loss position | Security | 65 |  | 65 |  | 8
Number of security positions, unrealized loss position for more than 12 months | Security | 3 |  | 3 |  | 1
Securities, 12 months or longer, Fair Value | $ 3,637,000 |  | $ 3,637,000 |  | $ 8,000
Securities, 12 months or longer, Unrealized Losses | $ 64,000 |  | $ 64,000 |  |
Number of security positions, unrealized loss position for less than 12 months | Security | 62 |  | 62 |  | 7
Securities, less than 12 months, Fair Value | $ 472,722,000 |  | $ 472,722,000 |  | $ 29,087,000
Securities, less than 12 months, Unrealized Losses | 6,043,000 |  | 6,043,000 |  | 68,000
Available for sale securities, allowance for credit loss | 0 |  | 0 |  | 0
Debt securities, held-to-maturity | 218,864,000 |  | 218,864,000 |  | 271,973,000
Investment securities, past due | 5,000,000 |  | 5,000,000 |  | 7,994,000
Investment securities, nonaccrual | 6,593,000 |  | 6,593,000 |  | 9,286,000
Municipal Bonds [Member] |  |  |  |  |
Schedule Of Investments [Line Items] |  |  |  |  |
Debt securities, held-to-maturity | 107,100,000 |  | 107,100,000 |  | 135,700,000
Internally rated held-to-maturity securities | 6,000,000.0 |  | 6,000,000.0 |  | 8,500,000
Municipal Bonds [Member] | Below Investment Grade [Member] |  |  |  |  |
Schedule Of Investments [Line Items] |  |  |  |  |
Investment grade rating exposure | 280,000 |  | $ 280,000 |  | $ 279,000
Investment grade rating exposure percentage |  |  | 0.25% |  | 0.19%
Maximum [Member] |  |  |  |  |
Schedule Of Investments [Line Items] |  |  |  |  |
Securities, 12 months or longer, Unrealized Losses | 64,000 |  | $ 64,000 |  | $ 1,000
Available for Sale Securities [Member] |  |  |  |  |
Schedule Of Investments [Line Items] |  |  |  |  |
Accrued interest receivable | 1,600,000 |  | 1,600,000 |  | 1,200,000
Held To Maturity Investment Securities [Member] |  |  |  |  |
Schedule Of Investments [Line Items] |  |  |  |  |
Accrued interest receivable | 751,000 |  | 751,000 |  | 905,000
Investment securities, past due | 0 |  | 0 |  | 0
Investment securities, nonaccrual | 0 |  | 0 |  | $ 0
Held To Maturity Investment Securities [Member] | Maximum [Member] |  |  |  |  |
Schedule Of Investments [Line Items] |  |  |  |  |
Credit loss expense | $ (1,000) | $ (5,000) | $ (1,000) | $ (6,000) |

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