Employee Benefit Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	$ 428	$ 446	$ 1,283	$ 1,338
Expected return on plan assets	(711)	(642)	(2,133)	(1,926)
Amortization of unrecognized net (gain) loss	112	119	338	357
Plan curtailment and special termination benefits				270
Total net periodic benefit cost	(171)	(77)	(512)	39
Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	8	13	24	37
Interest cost	46	51	138	151
Amortization	4	4	12	11
Amortization of unrecognized net (gain) loss	(70)	(79)	(210)	(238)
Plan curtailment and special termination benefits				150
Total net periodic benefit cost	$ (12)	$ (11)	$ (36)	$ 111