Investments (Major Categories of Net Investment Gains (Losses) on Investments) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Gain (Loss) on Securities [Line Items]
(Loss) gain on investments	$ 390,000	$ 175,000	$ 5,612,000	$ 4,376,000
Other-than-temporary impairment	(1,692,000)		(1,692,000)	0
Investment (losses) gains, net	(627,000)	(1,342,000)	(27,899,000)	17,412,000
Equity Securities [Member]
Gain (Loss) on Securities [Line Items]
Gain (loss) on equity securities			3,471,000
Unrealized gains (losses)	937,000	(1,941,000)	(29,683,000)	11,175,000
Other Investments [Member]
Gain (Loss) on Securities [Line Items]
Unrealized gains (losses)	(262,000)	424,000	(2,136,000)	1,861,000
U.S. Treasury Securities and Obligations of U.S. Government [Member] | Debt Securities [Member]
Gain (Loss) on Securities [Line Items]
Gain (loss) on debt securities	(3,000)		(3,000)
Corporate Bonds [Member] | Debt Securities [Member]
Gain (Loss) on Securities [Line Items]
Gain (loss) on debt securities	352,000	154,000	766,000	171,000
Collateralized Corporate Bank Loans [Member] | Debt Securities [Member]
Gain (Loss) on Securities [Line Items]
Gain (loss) on debt securities	66,000	(103,000)	(19,000)	(65,000)
Municipal Bonds [Member] | Debt Securities [Member]
Gain (Loss) on Securities [Line Items]
Gain (loss) on debt securities	$ (25,000)	$ 124,000	$ 1,397,000	4,271,000
Mortgage Backed [Member] | Debt Securities [Member]
Gain (Loss) on Securities [Line Items]
Gain (loss) on debt securities				$ (1,000)