Changes in Accumulated Other Comprehensive Income Balances (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 10,371
Other comprehensive income (loss):
Change in net actuarial gain (loss)	548	$ (145)	$ 43
Tax effect on change in net actuarial gain (loss)	(192)	51	(15)
Unrealized holding (losses) gains arising during the period	9,117	6,019	(10,191)
Tax effect on unrealized gains (losses) arising during the period	(3,191)	(2,107)	3,567
Reclassification adjustment for gains included in net realized gains	(6,799)	(1,331)	(5,826)
Tax effect on reclassification adjustment for gains included in income tax expense	2,380	466	2,039
Other comprehensive income, net of tax	1,863	2,953	(10,383)
Ending Balance	12,234	10,371
Pension Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2,666)	(2,572)	(2,600)
Other comprehensive income (loss):
Change in net actuarial gain (loss)	548	(145)	43
Tax effect on change in net actuarial gain (loss)	(192)	51	(15)
Other comprehensive income, net of tax	356	(94)	28
Ending Balance	(2,310)	(2,666)	(2,572)
Unrealized Gains (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	13,037	9,990	20,401
Other comprehensive income (loss):
Unrealized holding (losses) gains arising during the period	9,117	6,019	(10,191)
Tax effect on unrealized gains (losses) arising during the period	(3,191)	(2,107)	3,567
Reclassification adjustment for gains included in net realized gains	(6,799)	(1,331)	(5,826)
Tax effect on reclassification adjustment for gains included in income tax expense	2,380	466	2,039
Other comprehensive income, net of tax	1,507	3,047	(10,411)
Ending Balance	14,544	13,037	9,990
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	10,371	7,418	17,801
Other comprehensive income (loss):
Change in net actuarial gain (loss)	548	(145)	43
Tax effect on change in net actuarial gain (loss)	(192)	51	(15)
Unrealized holding (losses) gains arising during the period	9,117	6,019	(10,191)
Tax effect on unrealized gains (losses) arising during the period	(3,191)	(2,107)	3,567
Reclassification adjustment for gains included in net realized gains	(6,799)	(1,331)	(5,826)
Tax effect on reclassification adjustment for gains included in income tax expense	2,380	466	2,039
Other comprehensive income, net of tax	1,863	2,953	(10,383)
Ending Balance	12,234	10,371	$ 7,418
Parent Company [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	10,371
Other comprehensive income (loss):
Ending Balance	$ 12,234	$ 10,371