Investments (Equity Securities) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Debt and Equity Securities, FV-NI [Line Items]
Equity security	$ 15,672,000		$ 15,068,000
Realized investment gains (losses), net	5,961,000	$ (575,000)
Stock Mutual Funds [Member]
Debt and Equity Securities, FV-NI [Line Items]
Equity security	3,091,000		2,906,000
Bond Mutual Funds [Member]
Debt and Equity Securities, FV-NI [Line Items]
Equity security	12,143,000		11,774,000
Common stock [Member]
Debt and Equity Securities, FV-NI [Line Items]
Equity security	133,000		94,000
Nonredeemable Preferred Stock [Member]
Debt and Equity Securities, FV-NI [Line Items]
Equity security	305,000		$ 294,000
Equity Securities [Member]
Debt and Equity Securities, FV-NI [Line Items]
Realized investment gains (losses), net	$ 602,000	$ (302,000)