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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)	$ 147,071	$ (40,488)	$ 316,331	$ (201,336)
Income tax (expense) benefit	(28,422)	8,118	(71,907)	43,194
Noncontrolling interests	30	37	(18)	26
Total change in unrealized gains	118,679	(32,333)	244,406	(158,116)
Debt securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)	146,629	(36,848)	321,123	(196,575)
Previously impaired fixed maturity securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)	81	(2)	12	11
Investment funds
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized investment gains (losses)	$ 361	$ (3,638)	$ (4,804)	$ (4,772)