Investments (Schedule Of Trading Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Equity securities and other invested assets [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	$ 1,584,814	$ 1,656,706
Trading securities, Amortized Cost	1,443,489	1,516,275
Equity securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	815,641	844,163
Trading securities, Amortized Cost	757,592	791,206
Other invested assets [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	769,173	812,543
Trading securities, Amortized Cost	685,897	725,069
Fixed Maturities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	6,431,543	6,069,010
Trading securities, Amortized Cost	6,424,975	6,035,240
U.S. Government And Government Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,280,844	1,610,502
Trading securities, Amortized Cost	1,277,547	1,610,880
Non-U.S. Government And Government Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	411,550	188,199
Trading securities, Amortized Cost	421,778	196,332
States, Municipalities And Political Subdivisions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	348,823	170,567
Trading securities, Amortized Cost	348,288	165,615
Corporate Debt, Financial Institutions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,055,836	1,024,667
Trading securities, Amortized Cost	1,053,576	1,018,777
Corporate Debt, Industrials [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,226,827	1,029,729
Trading securities, Amortized Cost	1,238,948	1,037,820
Corporate Debt, Utilities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	121,571	110,997
Trading securities, Amortized Cost	122,793	111,599
Mortgage-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,263,019	1,263,517
Trading securities, Amortized Cost	1,234,126	1,219,712
Asset-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	723,073	670,832
Trading securities, Amortized Cost	$ 727,919	$ 674,505