Retirement Plans (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		$ 10,415	$ 10,419	$ 11,290	$ 10,851
Defined benefit plan, fair value of plan assets, excluding cash and cash equivalents		$ 10,091	$ 10,120
Favorable rate of return equal to or greater than average inflation rate		5.00%
Investment objective achievement period		60 years
Single stock issue restricted among total portfolio value		5.00%
Securities held in mutual or commingled funds		90.00%
Expected return on plan assets		6.50%	6.50%	6.50%
Net periodic pension cost		$ (29)	$ (80)	$ (4)
Interest cost on projected benefit obligation		512	518	532
Defined benefit plan, expected return on plan assets		(653)	(701)	(698)
Defined contribution plan, employer discretionary contribution amount		400	300	$ 300
Scenario, Forecast for 2017 [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension cost	$ (63)
Interest cost on projected benefit obligation	444
Defined benefit plan, expected return on plan assets	(649)
Defined benefit plan, amortization of losses (gains)	$ 142
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		300	300
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets, excluding cash and cash equivalents		$ 6,653	6,697
Defined benefit plan, target plan asset allocations range, minimum		45.00%
Defined benefit plan, target plan asset allocations range, maximum		75.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets, excluding cash and cash equivalents		$ 3,438	$ 3,423
Standard Commercial P & C Business Unit [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum hours of service to participate within defined benefit plan		1000 hours