Realized And Unrealized Investment Gains (Losses) on Investments (Realized and Unrealized Investments Gains (Losses)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Fixed maturity securities, gains	$ 4,931	$ 5,246
Fixed maturity securities, losses	(4,847)	(3,518)
Net realized gains on investment sales	0	23,345
Change in unrealized (losses) gains	(154,467)	42,078
Investment funds	30,183	17
Real estate	(687)	2,746
Loans receivable	0	(970)
Other	(18,398)	(291)
Net realized and unrealized (losses) gains on investments in earnings before allowance for expected credit losses	(143,285)	68,653
Fixed maturity securities	(31,750)	0
Loans receivable	(2,139)	0
Change in allowance for expected credit losses on investments	(33,889)	0
Net investment (losses) gains	(177,174)	68,653
Income tax benefit (expense)	37,207	(14,417)
After-tax net investment (losses) gains	$ (139,967)	$ 54,236