Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Benefits paid	$ 2,031	$ 1,885
Defined contribution plan, contribution amount	925	658	$ 623
Defined Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	85,236	74,425
Recognized prior service (cost) benefit	0
Net gains (losses) as a component of net periodic benefit cost	1,409
Supplemental Executive Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	8,734	7,904
Contributions for plan	5,799	5,367	5,211
Benefits paid	247	$ 247	$ 243
Recognized prior service (cost) benefit	0
Net gains (losses) as a component of net periodic benefit cost	$ 582
Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset	51.00%
U.S. Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset	25.00%
Non-U.S. Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset	30.00%