Changes in Accumulated Other Comprehensive Income Balances (Schedule of Changes in Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Jan. 01, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 12,234			$ 12,234
Other comprehensive income:
Change in net actuarial gain		$ 27	$ 37	80	$ 107
Tax effect on change in net actuarial gain		(6)	(13)	(17)	(37)
Net unrealized holding gains (losses) arising during the period		342	308	1,909	8,208
Tax effect on unrealized gains arising during the period		(72)	(108)	(401)	(2,873)
Reclassification adjustment for realized gains included in investment gains		166	(3,188)	159	(5,679)
Tax effect on reclassification adjustment for realized gains included in income tax expense		(35)	1,116	(33)	1,988
Other comprehensive income, net of tax		422	(1,848)	1,697	1,714
Reclassification of certain tax effects from accumulated other comprehensive income at January 1, 2018	(2,600)
Ending Balance		(443)		(443)
Minimum Pension Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2,310)			(2,310)	(2,666)
Other comprehensive income:
Change in net actuarial gain				80	107
Tax effect on change in net actuarial gain				(17)	(37)
Other comprehensive income, net of tax				63	70
Reclassification of certain tax effects from accumulated other comprehensive income at January 1, 2018				(569)
Ending Balance		(2,816)	(2,596)	(2,816)	(2,596)
Unrealized Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	14,544			14,544	13,037
Other comprehensive income:
Net unrealized holding gains (losses) arising during the period				1,909	8,208
Tax effect on unrealized gains arising during the period				(401)	(2,873)
Reclassification adjustment for realized gains included in investment gains				159	(5,679)
Tax effect on reclassification adjustment for realized gains included in income tax expense				(33)	1,988
Other comprehensive income, net of tax				1,634	1,644
Reclassification of certain tax effects from accumulated other comprehensive income at January 1, 2018				3,188
Cumulative effect of adoption of updated accounting guidance for equity financial instruments at January 1, 2018		(16,993)		(16,993)
Ending Balance		2,373	14,681	2,373	14,681
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 12,234			12,234	10,371
Other comprehensive income:
Change in net actuarial gain				80	107
Tax effect on change in net actuarial gain				(17)	(37)
Net unrealized holding gains (losses) arising during the period				1,909	8,208
Tax effect on unrealized gains arising during the period				(401)	(2,873)
Reclassification adjustment for realized gains included in investment gains				159	(5,679)
Tax effect on reclassification adjustment for realized gains included in income tax expense				(33)	1,988
Other comprehensive income, net of tax				1,697	1,714
Reclassification of certain tax effects from accumulated other comprehensive income at January 1, 2018				2,619
Cumulative effect of adoption of updated accounting guidance for equity financial instruments at January 1, 2018		(16,993)		(16,993)
Ending Balance		$ (443)	$ 12,085	$ (443)	$ 12,085