Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands |
Jun. 30, 2019 |
Mar. 31, 2019 |
Dec. 31, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2017 |
---|---|---|---|---|---|---|
Accumulated Other Comprehensive Income (Loss) [Line Items] | ||||||
Components of accumulated other comprehensive loss | $ 180,884 | $ 173,793 | $ 168,137 | $ 160,307 | $ 156,605 | $ 153,966 |
Unrealized Gains (Losses) on Securities | ||||||
Accumulated Other Comprehensive Income (Loss) [Line Items] | ||||||
Components of accumulated other comprehensive loss | 946 | (1,651) | (2,748) | |||
Pension Liability | ||||||
Accumulated Other Comprehensive Income (Loss) [Line Items] | ||||||
Components of accumulated other comprehensive loss | (7,238) | (7,566) | (5,935) | |||
Accumulated Other Comprehensive Loss | ||||||
Accumulated Other Comprehensive Income (Loss) [Line Items] | ||||||
Components of accumulated other comprehensive loss | $ (6,292) | $ (7,943) | $ (9,217) | $ (8,683) | $ (8,281) | $ (7,092) |