Investments (Net Investment Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 517,377	$ 606,468	$ 571,577
Less: investment expenses	(26,984)	(27,207)	(20,029)
Net investment income	490,393	579,261	551,548
Equity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	5,499	1,397	568
Commercial mortgage and other loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	64,997	56,483	51,628
Policy loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	632	724	630
Other invested assets
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	62,137	43,244	34,422
Short-term investments and cash equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	1,237	49,929	85,084
Available-for-sale | Fixed maturities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	353,955	440,271	389,165
Trading | Fixed maturities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 28,920	$ 14,420	$ 10,080