Investments (Schedule Of Trading Securities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 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	$ 1,674,880	$ 1,463,927
Trading securities, Amortized Cost	1,522,312	1,305,984
Equity securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	834,893	699,846
Trading securities, Amortized Cost	803,954	647,301
Other invested assets [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	839,987	764,081
Trading securities, Amortized Cost	718,358	658,683
Fixed Maturities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	6,068,666	6,100,798
Trading securities, Amortized Cost	6,010,765	6,065,350
U.S. Government And Government Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,476,463	1,676,788
Trading securities, Amortized Cost	1,480,371	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	182,415	191,776
Trading securities, Amortized Cost	187,632	197,082
States, Municipalities And Political Subdivisions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	230,669	231,555
Trading securities, Amortized Cost	228,284	234,406
Corporate Debt, Financial Institutions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,097,649	958,794
Trading securities, Amortized Cost	1,083,131	943,518
Corporate Debt, Industrials [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,116,004	1,174,047
Trading securities, Amortized Cost	1,105,613	1,165,448
Corporate Debt, Utilities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	96,807	69,426
Trading securities, Amortized Cost	96,403	69,658
Mortgage-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	1,304,130	1,292,502
Trading securities, Amortized Cost	1,266,663	1,267,863
Asset-Backed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading securities, Fair Value	564,529	505,910
Trading securities, Amortized Cost	$ 562,668	$ 502,543