Investments (Other Than Temporary Impairments) (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Other than temporary impairments Losses, Investments, Portion Not Recognized in Earnings			$ 0		$ 0
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net		$ 0
Equity Securities [Member]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	$ 0	$ 0	0	$ 17,000
Number of equity securities impaired				1
Debt Securities [Member]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	$ 551,000		$ 776,000