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Accumulated Other Comprehensive Income (Changes in AOCI by Component) (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018 | Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |  |  |  |  |  |  |  |
Beginning balance |  | $ 47,150 |  | $ (55,921) |  | $ (35,305) |  | $ (22,225) |  |
Other comprehensive income before reclassifications | [1] | 17,730 |  | (14,149) |  | 101,699 |  | (48,043) |  |
Amounts reclassified from accumulated other comprehensive income (2) | [1] | 4 |  | 61 |  | (1,510) |  | 102 |  |
Net current-period other comprehensive income | [1] | 17,734 |  | (14,088) |  | 100,189 |  | (47,941) |  |
Ending balance |  | 64,884 |  | (70,009) |  | 64,884 |  | (70,009) |  |
Unrealized Gains and Losses on Available-for-Sale Debt Securities [Member] |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |  |  |  |  |  |  |  |
Beginning balance |  | 37,162 |  | (53,597) |  | (33,128) |  | (19,779) |  |
Other comprehensive income before reclassifications | [1] | 14,593 |  | (14,149) |  | 86,519 |  | (48,043) |  |
Amounts reclassified from accumulated other comprehensive income (2) |  | 0 | [2] | 0 | [1] | (1,636) | [1] | (81) | [1] |
Net current-period other comprehensive income | [1] | 14,593 |  | (14,149) |  | 84,883 |  | (48,124) |  |
Ending balance |  | 51,755 |  | (67,746) |  | 51,755 |  | (67,746) |  |
Unrealized Gains and Losses on Pension Plan Liability [Member] |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |  |  |  |  |  |  |  |
Beginning balance |  | (2,055) |  | (2,324) |  | (2,177) |  | (2,446) |  |
Other comprehensive income before reclassifications | [1] | 0 |  | 0 |  | 0 |  | 0 |  |
Amounts reclassified from accumulated other comprehensive income (2) | [1] | 62 |  | 61 |  | 184 |  | 183 |  |
Net current-period other comprehensive income | [1] | 62 |  | 61 |  | 184 |  | 183 |  |
Ending balance |  | (1,993) |  | (2,263) |  | (1,993) |  | (2,263) |  |
Unrealized gains and losses on cash flow hedge |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |  |  |  |  |  |  |  |
Beginning balance |  | 12,043 |  | 0 |  | 0 |  | 0 |  |
Other comprehensive income before reclassifications |  | 3,137 | [1] | 0 | [1] | 15,180 | [2] | 0 | [1] |
Amounts reclassified from accumulated other comprehensive income (2) | [2] | (58) |  | 0 |  | (58) |  | 0 |  |
Net current-period other comprehensive income | [1] | 3,079 |  | 0 |  | 15,122 |  | 0 |  |
Ending balance |  | $ 15,122 |  | $ 0 |  | $ 15,122 |  | $ 0 |  |
Accounting Standards Update 2016-01 [Member] |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  |  |  |  |  |  |  |  | $ 0
Accounting Standards Update 2016-01 [Member] | Unrealized Gains and Losses on Available-for-Sale Debt Securities [Member] |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  |  |  |  |  |  |  |  | 157
Accounting Standards Update 2016-01 [Member] | Unrealized Gains and Losses on Pension Plan Liability [Member] |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  |  |  |  |  |  |  |  | 0
Accounting Standards Update 2016-01 [Member] | Unrealized gains and losses on cash flow hedge |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  |  |  |  |  |  |  |  | 0
Accounting Standards Update 2016-01 [Member] | Accumulated Other Comprehensive Income [Member] |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  |  |  |  |  |  |  |  | $ 157
[1] | All amounts are net of tax. Amounts in parenthesis indicate debits.
[2] | (2) See following table for details about these reclassifications.

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