Components of Net Periodic Benefit (Income) Cost | | | | | | | | | | | | | | | | | | | | | | | | | | Pension Benefits Three Months Ended | | Life and Health Three Months Ended | | SERP Benefits Three Months Ended | (in thousands) | 3/31/2018 |
| | 3/31/2017 |
| | 3/31/2018 |
| | 3/31/2017 |
| | 3/31/2018 |
| | 3/31/2017 |
| Service cost | $ | 0 |
| | $ | 0 |
| | $ | 53 |
| | $ | 68 |
| | $ | 45 |
| | $ | 54 |
| Interest cost | 591 |
| | 607 |
| | 65 |
| | 71 |
| | 206 |
| | 209 |
| Expected return on plan assets | (1,417 | ) | | (1,267 | ) | | 0 |
| | 0 |
| | 0 |
| | 0 |
| Amortization of net retirement plan actuarial loss | 267 |
| | 252 |
| | 15 |
| | 4 |
| | 135 |
| | 101 |
| Amortization of net retirement plan prior service (credit) cost | (3 | ) | | (3 | ) | | (15 | ) | | 4 |
| | 22 |
| | 22 |
| Net periodic benefit (income) cost | $ | (562 | ) | | $ | (411 | ) | | $ | 118 |
| | $ | 147 |
| | $ | 408 |
| | $ | 386 |
|
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