Pension and Other Postretirement Plans (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) benefit_plan	Dec. 31, 2017 USD ($)	Dec. 31, 2007
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 21,900	$ 24,700
Average rate of return (in percentage)	8.66%
Average rate of return, inception to date (in percentage)	6.90%
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	$ 18,100	$ 20,700
Amortization of net loss	500
Amortization of prior service cost	59
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	600
Defined Benefit Postretirement Healthcare Plans
Defined Benefit Plan Disclosure [Line Items]
Amortization of net loss	79
Amortization of prior service cost	$ 52