Investment Income and Gains and Losses (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Gain (Loss) on Investments [Line Items]
Net unrealized gains (losses) recognized during the period on equity securities still held	$ (20,600,000)	$ 116,900,000	$ 33,200,000
Fixed maturity securities on non-accrual	0	0
Impairment losses on investment securities	16,700,000	700,000	26,300,000
Impairments on fixed maturities credit related losses	3,700,000		1,100,000
Impairments on fixed maturities included intend to sell			16,500,000
Fixed Maturities [Member]
Gain (Loss) on Investments [Line Items]
Impairment losses on investment securities	18,500,000	1,300,000	17,600,000
Fixed Maturities Intent to Sell Securities [Member]
Gain (Loss) on Investments [Line Items]
Impairment losses on investment securities	14,800,000
Mortgage Loans on Real Estate [Member]
Gain (Loss) on Investments [Line Items]
Impairment losses on investment securities		600,000
Impairments on fixed maturities partially offset by recoveries	1,800,000
Impairments on fixed maturities credit related losses			6,700,000
Allowance for credit losses	3,200,000	7,100,000
Fixed Maturities Including Held For Sale [Member]
Gain (Loss) on Investments [Line Items]
Allowance for credit losses	2,100,000	300,000
Investments Net Asset Value [Member]
Gain (Loss) on Investments [Line Items]
Net unrealized gains (losses) recognized during the period on equity securities still held	$ (2,000,000.0)	$ 17,100,000	$ (6,900,000)