Investments (Changes in Net Unrealized Gains/Losses on Investments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Investments [Abstract]
Fixed maturity securities available for sale carried at fair value	$ 800,492	$ 990,481	$ 1,285,600	$ 3,891,291
Adjustment for effect on other balance sheet accounts:
Deferred policy acquisition costs and deferred sales inducements	(303,946)	(245,044)	(508,144)	(1,750,390)
Deferred income tax asset/liability	(104,274)	(155,992)	(163,266)	(449,040)
Total adjustment for effect on other balance sheet accounts	(408,220)	(401,036)	(671,410)	(2,199,430)
Change in net unrealized gains/losses on investments carried at fair value	$ 392,272	$ 589,445	$ 614,190	$ 1,691,861