Pension and Other Postretirement Plans (Narrative) (Details) |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2016
USD ($)
benefit_plan
|
Dec. 31, 2015
USD ($)
|
Dec. 31, 2007 |
|
| Defined Benefit Plan Disclosure [Line Items] | |||
| Accumulated benefit obligation | $ 24,600,000 | $ 25,500,000 | |
| Amortization of net loss | 17,000 | ||
| Amortization of prior service cost | $ 103,000 | ||
| Average rate of return (in percentage) | 5.66% | ||
| Average rate of return, inception to date (in percentage) | 7.02% | ||
| Number of non-qualified defined benefit pension plan | benefit_plan | 3 | ||
| Chairman and President Non-Qualified Defined Benefit Plans | |||
| Defined Benefit Plan Disclosure [Line Items] | |||
| Accumulated benefit obligation | $ 18,500,000 | $ 19,500,000 | |
| Amortization of net loss | 1,705,000 | ||
| Amortization of prior service cost | 59,000 | ||
| Defined Benefit Pension Plans | |||
| Defined Benefit Plan Disclosure [Line Items] | |||
| Vesting percentage in accrued benefits from plan freeze (in percentage) | 100.00% | ||
| Amortization of net loss | $ (620,600) |