Investments (Schedule Of Amortized Cost And Estimated Fair Value Of Fixed Maturities By Contractual Maturity Date) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, amortized cost	$ 685,920
Due after one year through five years, amortized cost	2,273,952
Due after five years through ten years, amortized cost	2,128,510
Due after ten years, amortized cost	3,364,953
Amortized cost, sub-total	8,453,335
Total fixed maturities, amortized cost	9,983,583	10,129,141
Due in one year or less, estimated fair value	692,956
Due after one year through five years, estimated fair value	2,331,498
Due after five years through ten years, estimated fair value	2,226,376
Due after ten years, estimated fair value	3,500,941
Estimated fair value, sub-total	8,751,771
Total fixed maturities, estimated fair value	10,293,228	10,142,536
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, amortized cost	384,657
Fixed maturities, estimated fair value	383,865
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, amortized cost	995,488
Fixed maturities, estimated fair value	1,008,121
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, amortized cost	150,103
Fixed maturities, estimated fair value	$ 149,471