Employee Benefit Plan - Weighed Average Assumptions Used (Details)
|
12 Months Ended |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
| Discount Rates |
|
|
|
| Expected long-term return on plan assets |
7.25%
|
7.25%
|
7.25%
|
| DB Pension Plan |
|
|
|
| Discount Rates |
|
|
|
| Benefit Cost for Plan Year |
3.89%
|
4.05%
|
3.81%
|
| Benefit Obligation at End of Plan Year |
3.43%
|
3.89%
|
4.05%
|
| Expected long-term return on plan assets |
7.25%
|
|
|
| Rate of compensation increase |
|
|
|
| Benefit Cost for Plan Year |
|
|
5.00%
|
| Benefit Obligation at End of Plan Year |
|
|
5.00%
|
| Life and Healthcare Plan |
|
|
|
| Discount Rates |
|
|
|
| Benefit Cost for Plan Year |
3.97%
|
4.14%
|
3.80%
|
| Benefit Obligation at End of Plan Year |
3.51%
|
3.97%
|
4.14%
|
| Rate of compensation increase |
|
|
|
| Benefit Cost for Plan Year |
5.00%
|
5.00%
|
5.00%
|
| Benefit Obligation at End of Plan Year |
5.00%
|
5.00%
|
5.00%
|
| SERPs |
|
|
|
| Discount Rates |
|
|
|
| Benefit Cost for Plan Year |
4.10%
|
4.32%
|
4.00%
|
| Benefit Obligation at End of Plan Year |
3.55%
|
4.10%
|
4.32%
|
| Rate of compensation increase |
|
|
|
| Benefit Cost for Plan Year |
5.00%
|
5.00%
|
5.00%
|
| Benefit Obligation at End of Plan Year |
5.00%
|
5.00%
|
5.00%
|