Investments (Schedule Of Trading Securities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Equity securities and other invested assets [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	$ 1,656,706	$ 1,463,927
Trading securities, Amortized Cost	1,516,275	1,305,984
Equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	844,163	699,846
Trading securities, Amortized Cost	791,206	647,301
Other invested assets
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	812,543	764,081
Trading securities, Amortized Cost	725,069	658,683
Fixed Maturities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	6,069,010	6,100,798
Trading securities, Amortized Cost	6,035,240	6,065,350
U.S. Government and Government Agencies
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,610,502	1,676,788
Trading securities, Amortized Cost	1,610,880	1,684,832
Non-U.S. Government and Government Agencies
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	188,199	191,776
Trading securities, Amortized Cost	196,332	197,082
States, municipalities and political subdivisions
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	170,567	231,555
Trading securities, Amortized Cost	165,615	234,406
Corporate debt: financial institutions
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,024,667	958,794
Trading securities, Amortized Cost	1,018,777	943,518
Corporate debt: Industrials
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,029,729	1,174,047
Trading securities, Amortized Cost	1,037,820	1,165,448
Corporate debt: utilities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	110,997	69,426
Trading securities, Amortized Cost	111,599	69,658
Mortgage-backed
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,263,517	1,292,502
Trading securities, Amortized Cost	1,219,712	1,267,863
Asset-backed
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	670,832	505,910
Trading securities, Amortized Cost	$ 674,505	$ 502,543