Investments (Schedule Of Amortized Cost And Estimated Fair Value Of Fixed Maturities By Contractual Maturity Date) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, amortized cost	$ 311,759
Due after one year through five years, amortized cost	1,282,826
Due after five years through ten years, amortized cost	1,617,285
Due after ten years, amortized cost	1,345,958
Amortized cost, sub-total	4,557,828
Fixed maturities, amortized cost	4,833,249	5,172,952
Due in one year or less, estimated fair value	316,794
Due after one year through five years, estimated fair value	1,398,701
Due after five years through ten years, estimated fair value	1,773,272
Due after ten years, estimated fair value	1,498,431
Estimated fair value, sub-total	4,987,198
Fixed maturities, estimated fair value	5,280,549	5,538,174
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, amortized cost	261,089
Fixed maturities, estimated fair value	278,343
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, amortized cost	14,332
Fixed maturities, estimated fair value	$ 15,008