Net Investment Gains (Losses) (Change in Unrealized Gains (Losses) of Available For Sales Securities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Realized and Unrealized Investment Gains Losses [Line Items]
Unrealized investment gains, before tax	$ 164,645	$ 261,970	$ (302,737)
Income tax (expense) benefit	(24,395)	(46,068)	50,410
Noncontrolling interests	(2)	103	(46)
Total change in unrealized gains and losses	140,248	216,005	(252,373)
Debt Securities
Realized and Unrealized Investment Gains Losses [Line Items]
Unrealized investment gains, before tax	134,129	271,825	(297,084)
Fixed maturity securities with allowance for expected credit losses
Realized and Unrealized Investment Gains Losses [Line Items]
Unrealized investment gains, before tax	32,004	369	(132)
Investment funds
Realized and Unrealized Investment Gains Losses [Line Items]
Unrealized investment gains, before tax	2,280	(2,299)	(5,672)
Other
Realized and Unrealized Investment Gains Losses [Line Items]
Unrealized investment gains, before tax	$ (3,768)	$ (7,925)	$ 151