Investments (Schedule Of Trading Securities) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 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	$ 1,742,622	$ 1,463,927
Trading securities, Amortized Cost	1,579,231	1,305,984
Equity securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	938,117	699,846
Trading securities, Amortized Cost	885,861	647,301
Other invested assets [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	804,505	764,081
Trading securities, Amortized Cost	693,370	658,683
Fixed Maturities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	6,157,084	6,100,798
Trading securities, Amortized Cost	6,062,758	6,065,350
U.S. Government And Government Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,274,331	1,676,788
Trading securities, Amortized Cost	1,273,469	1,684,832
Non-U.S. Government And Government Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	185,071	191,776
Trading securities, Amortized Cost	186,142	197,082
States, Municipalities And Political Subdivisions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	261,267	231,555
Trading securities, Amortized Cost	256,698	234,406
Corporate Debt, Financial Institutions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,168,937	958,794
Trading securities, Amortized Cost	1,149,005	943,518
Corporate Debt, Industrials [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,167,470	1,174,047
Trading securities, Amortized Cost	1,152,858	1,165,448
Corporate Debt, Utilities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	98,878	69,426
Trading securities, Amortized Cost	97,457	69,658
Mortgage-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,323,763	1,292,502
Trading securities, Amortized Cost	1,272,824	1,267,863
Asset-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	677,367	505,910
Trading securities, Amortized Cost	$ 674,305	$ 502,543