Defined Pension Plans (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Pension period	30 years
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension costs	$ 1,049	$ 1,020
Unfunded Supplemental Executive Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension costs	$ 255	$ 209