Changes in accumulated other comprehensive income by component, net of tax, were as follows for the periods indicated: | | | | | | | | | | | | | | Three Months Ended March 31, 2020 | | Investment Securities Available-for-Sale | | Postretirement Benefits | | Accumulated Other Comprehensive Loss | | (In Thousands) | Balance at December 31, 2019 | $ | 2,199 |
| | $ | 84 |
| | $ | 2,283 |
| Other comprehensive income | 14,664 |
| | — |
| | 14,664 |
| Balance at March 31, 2020 | $ | 16,863 |
| | $ | 84 |
| | $ | 16,947 |
|
| | | | | | | | | | | | | | Three Months Ended March 31, 2019 | | Investment Securities Available-for-Sale | | Postretirement Benefits | | Accumulated Other Comprehensive Loss | | (In Thousands) | Balance at December 31, 2018 | $ | (9,712 | ) | | $ | 252 |
| | $ | (9,460 | ) | Other comprehensive income | 5,067 |
| | — |
| | 5,067 |
| Balance at March 31, 2019 | $ | (4,645 | ) | | $ | 252 |
| | $ | (4,393 | ) |
|