Investments (Net Unrealized Gains Losses on Investments by Asset Class) (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Gain (Loss) on Securities [Line Items]
Net Unrealized Gains (Losses) on Investments	$ (2,024,868)	$ (2,156,655)
Fixed maturities | Available-for-sale | With an allowance
Gain (Loss) on Securities [Line Items]
Net Unrealized Gains (Losses) on Investments	3,781	4,371
Fixed maturities | Available-for-sale | Without an allowance
Gain (Loss) on Securities [Line Items]
Net Unrealized Gains (Losses) on Investments	(2,114,982)	(2,285,288)
Derivatives designated as cash flow hedges
Gain (Loss) on Securities [Line Items]
Net Unrealized Gains (Losses) on Investments	99,661	138,627
Affiliated notes
Gain (Loss) on Securities [Line Items]
Net Unrealized Gains (Losses) on Investments	(12,179)	(13,189)
Other investments
Gain (Loss) on Securities [Line Items]
Net Unrealized Gains (Losses) on Investments	$ (1,149)	$ (1,176)