Net Investment Gains (Losses) (Change in Unrealized Gains (Losses) of Available For Sales Securities) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	$ 395,624	$ 147,071	$ 62,777	$ 316,331
Income tax expense	(76,899)	(28,422)	(3,034)	(71,907)
Noncontrolling interests	(1)	30	1	(18)
Total change in unrealized gains	318,724	118,679	59,744	244,406
Debt securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	369,615	146,629	43,199	321,123
Fixed maturity securities with allowance for expected credit losses
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	23,450	81	24,991	12
Investment funds
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	4,212	5,762	(3,434)	7,552
Other
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains	$ (1,653)	$ (5,401)	$ (1,979)	$ (12,356)