Investments (Schedule Of Trading Securities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 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	$ 1,649,221	$ 1,656,706
Trading securities, Amortized Cost	1,499,912	1,516,275
Equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	856,652	844,163
Trading securities, Amortized Cost	798,275	791,206
Other invested assets
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	792,569	812,543
Trading securities, Amortized Cost	701,637	725,069
Fixed Maturities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	6,288,897	6,069,010
Trading securities, Amortized Cost	6,229,608	6,035,240
U.S. Government And Government Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,577,775	1,610,502
Trading securities, Amortized Cost	1,569,317	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	189,448	188,199
Trading securities, Amortized Cost	204,867	196,332
States, Municipalities And Political Subdivisions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	178,551	170,567
Trading securities, Amortized Cost	172,339	165,615
Corporate Debt, Financial Institutions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,107,108	1,024,667
Trading securities, Amortized Cost	1,094,338	1,018,777
Corporate Debt, Industrials [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,107,548	1,029,729
Trading securities, Amortized Cost	1,105,744	1,037,820
Corporate Debt, Utilities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	113,383	110,997
Trading securities, Amortized Cost	113,280	111,599
Mortgage-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,286,210	1,263,517
Trading securities, Amortized Cost	1,238,165	1,219,712
Asset-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	728,874	670,832
Trading securities, Amortized Cost	$ 731,558	$ 674,505