Pension and Other Postretirement Plans (Assumptions) (Details) - USD ($)
$ in Thousands |
12 Months Ended |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Defined Benefit Pension Plans |
|
|
|
| Weighted-average assumptions used to determine benefit obligations |
|
|
|
| Discount rate (in percentage) |
4.00%
|
4.00%
|
|
| Weighted-average assumptions used to determine net periodic benefit cost |
|
|
|
| Discount rate (in percentage) |
4.00%
|
3.75%
|
4.60%
|
| Expected long-term return on plan assets (in percentage) |
7.00%
|
7.00%
|
7.00%
|
| Chairman and President Non-Qualified Defined Benefit Plans |
|
|
|
| Weighted-average assumptions used to determine benefit obligations |
|
|
|
| Discount rate (in percentage) |
4.00%
|
4.00%
|
|
| Rate of compensation increase (in percentage) |
8.00%
|
4.00%
|
|
| Weighted-average assumptions used to determine net periodic benefit cost |
|
|
|
| Discount rate (in percentage) |
4.00%
|
3.75%
|
4.60%
|
| Rate of compensation increase (in percentage) |
8.00%
|
4.00%
|
4.00%
|
| Defined Benefit Postretirement Healthcare Plans |
|
|
|
| Weighted-average assumptions used to determine benefit obligations |
|
|
|
| Discount rate (in percentage) |
4.00%
|
4.00%
|
|
| Annual rate of increase in the per capita cost of covered health care benefits (in percentage) |
10.00%
|
|
|
| Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract] |
|
|
|
| Effect on total of service and interest cost components, 1% point increase |
$ 31
|
$ 35
|
|
| Effect on total of service and interest cost components, 1% point decrease |
(23)
|
(26)
|
|
| Effect on postretirement benefit obligation, 1% point increase |
801
|
913
|
|
| Effect on postretirement benefit obligation, 1% point decrease |
$ (611)
|
$ (679)
|
|