Investments (Amortized Cost And Fair Value Of Fixed Maturity Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, cost or amortized cost	$ 324,097
Due after one year through five years, cost or amortized cost	1,904,357
Due after five years through ten years, cost or amortized cost	2,121,934
Due after ten years, cost or amortized cost	4,141,492
Total fixed maturity securities, cost or amortized cost	8,491,880
Fixed maturity securities available for sale, amortized cost	9,470,795	$ 10,048,100
Due in one year or less, fair value	327,824
Due after one year through five years, fair value	1,984,818
Due after five years through ten years, fair value	2,171,426
Due after ten years, fair value	4,705,563
Total fixed maturity securities, fair value	9,189,631
Fixed maturity securities, fair value	10,215,328	$ 11,263,174
Residential mortgage-backed
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	953,247
Fair Value	998,514
Commercial mortgage-backed
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	22,169
Fair Value	22,521
Asset-backed
Schedule of Available-for-sale Securities [Line Items]
Cost or amortized cost	3,499
Fair Value	$ 4,662