Realized And Unrealized Investment Gains (Losses) on Investments (Change in Unrealized Gains (Losses) of Available For Sales Securities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment (losses) gains	$ (332,850)	$ 169,260
Income tax benefit (expense)	73,869	(43,486)
Noncontrolling interests	1	(47)
Total change in unrealized gains	(258,980)	125,727
Debt securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment (losses) gains	(326,416)	174,494
Fixed maturity securities with allowance for expected credit losses
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment (losses) gains	1,541	(69)
Investment funds
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment (losses) gains	(7,646)	1,790
Other
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment (losses) gains	$ (329)	$ (6,955)