Investments (Major Categories of Net Investment Gains (Losses) on Investments) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Gain (Loss) on Securities [Line Items]
Gain on debt securities			$ 600	$ 0
Gain on investments	$ 1,059	$ 390	5,288	5,612
Other-than-temporary impairment		(1,692)	0	(1,692)
Investment (losses) gains, net	(533)	(627)	9,122	(27,899)
Equity Securities [Member]
Gain (Loss) on Securities [Line Items]
Gain on equity securities	930		4,701	3,471
Unrealized (losses) gains	(1,592)	937	3,834	(29,683)
Other Investments [Member]
Gain (Loss) on Securities [Line Items]
Unrealized (losses) gains		(262)		(2,136)
U.S. Treasury securities and obligations of U.S. Government [Member] \| Debt Securities [Member]
Gain (Loss) on Securities [Line Items]
Gain on debt securities		(3)		(3)
Corporate Bonds [Member] \| Debt Securities [Member]
Gain (Loss) on Securities [Line Items]
Gain on debt securities	133	352	494	766
Corporate bank loans [Member] \| Debt Securities [Member]
Gain (Loss) on Securities [Line Items]
Gain on debt securities	14	66	105	(19)
Municipal Bonds [Member] \| Debt Securities [Member]
Gain (Loss) on Securities [Line Items]
Gain on debt securities	$ (18)	$ (25)	$ (12)	$ 1,397

Amount of unrealized and realized gain (loss) on investment in debt and equity securities.

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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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