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Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2020 | Jan. 27, 2021 | Dec. 31, 2019 | Dec. 31, 2018
Stockholders' Equity [Abstract] |  |  |  |
Unrecognized prior service cost and net actuarial (losses) on pension plans | $ (20,134) |  | $ (21,677) | $ (27,689)
Unrealized (losses) gains on derivatives (cash flow hedges) | (16) |  | (32) | 1,821
Unrealized net holding gains (losses) on AFS securities | 20,567 |  | 2,683 | (17,306)
AOCI | $ 417 |  | $ (19,026) | $ (43,174)
Preceding period of retained net profits for approval of Office of Comptroller of the Currency | 2 years |  |  |
Statutory amount available for dividend payments | $ 194,200 |  |  |
Stock Repurchase Program [Abstract] |  |  |  |
Purchase of common stock (in shares) | 263,507 |  |  |
Purchase of common stock value | $ 7,980 |  |  |
Average price per share (in dollars per share) | $ 30.28 |  |  |
Number of shares available for repurchase under stock repurchase program (in shares) | 736,493 |  |  |
Number of shares authorized under stock repurchase program (in shares) | 1,000,000 |  |  |
Subsequent Event [Member] |  |  |  |
Stock Repurchase Program [Abstract] |  |  |  |
Number of shares authorized under stock repurchase program (in shares) |  | 2,000,000 |  |

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- Definition Preceding period of retained net profits for approval of Office of Comptroller of the Currency, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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