Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Company plan contirbutions	$ 445	$ 212	$ 341
Unrecognized prior service cost reduction	$ 1,100
Assumed health care cost trend rate	5.80%
Ultimate health care cost trend rate	4.60%
Year that plan rate reaches ultimate health care cost trend rate	2066
Discount rate used to determine year-end expense	3.30%	4.50%	4.50%
Pension Plan [Member]
Discount rate used to determine year-end expense	4.50%