Investments (Net Realized and Unrealized Investment Gains and (Losses)) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Gain (Loss) on Securities [Line Items]
Gross gains on sales	$ 2,079	$ 6,478	$ 5,755	$ 12,151
Gross losses on sales	(1,811)	(3,863)	(6,282)	(5,436)
Net realized investment gains (losses) on disposals	268	2,615	(527)	6,715
Net unrealized gains (losses) on equity securities	7,661	5,701	18,941	(11,436)
Losses on securities for which we have the intent to sell	(91)	(613)	(453)	(16,215)
Net realized and unrealized investment gains (losses)	10,057	12,649	15,176	(32,017)
Available-for-sale Securities [Member]
Gain (Loss) on Securities [Line Items]
Net credit loss benefit (expense) on fixed maturities	2,272	4,923	(2,725)	(10,864)
Held-to-maturity Securities [Member]
Gain (Loss) on Securities [Line Items]
Net credit loss benefit (expense) on fixed maturities	(53)	1	(60)	1
Commercial Mortgage Loans [Member]
Gain (Loss) on Securities [Line Items]
Net credit loss benefit (expense) on fixed maturities	$ 0	$ 22	$ 0	$ (218)

The credit loss expensed during the period on investment portfolio.

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This item represents the gross gain realized on sales of debt and equity investments.

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Losses on investment securities for which we have the intent to sell

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

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

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of realized and unrealized gain (loss) on investment.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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