Credit Facilities (Narrative) (Details) (USD $)	12 Months Ended			12 Months Ended				12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Group Credit Facility [Member]	Dec. 31, 2011 Group Credit Facility [Member] Everest Re Group Ltd [Member]	Dec. 31, 2011 Holdings Credit Facility [Member]	Aug. 15, 2011 Holdings Credit Facility [Member] years	Aug. 23, 2006 Holdings Credit Facility [Member] years	Dec. 31, 2011 Holdings Credit Facility [Member] Everest Re Group Ltd [Member]	Dec. 31, 2011 Bermuda Re Letter Of Credit Facility [Member]	Dec. 31, 2011 Maximum [Member]	Dec. 31, 2011 Wells Fargo Bank Group Credit Facility [Member]	Dec. 31, 2010 Wells Fargo Bank Group Credit Facility [Member]	Jul. 27, 2007 Wells Fargo Bank Group Credit Facility [Member] Group Credit Facility [Member]	Dec. 31, 2011 Wells Fargo Bank Group Credit Facility Tranche One [Member]	Dec. 31, 2010 Wells Fargo Bank Group Credit Facility Tranche One [Member]	Jul. 27, 2007 Wells Fargo Bank Group Credit Facility Tranche One [Member] Group Credit Facility [Member]	Dec. 31, 2011 Wells Fargo Bank Group Credit Facility Tranche Two [Member]	Dec. 31, 2010 Wells Fargo Bank Group Credit Facility Tranche Two [Member]	Jul. 27, 2007 Wells Fargo Bank Group Credit Facility Tranche Two [Member] Group Credit Facility [Member]	Dec. 31, 2011 Revolving Credit [Member]	Dec. 31, 2011 Standby Letters Of Credit [Member]
Line of Credit Facility [Line Items]
Line of credit facilities, number of facilities	3
Line of credit facility, number of years						3	5		5
Credit facilities, total commitment	$ 127,000.000										$ 446,454,000	$ 406,427,000					$ 446,327,000	$ 406,427,000
Group Credit Facility, number of tranches													2							1	2
Senior credit facility							150,000,000		300,000,000				850,000,000
Maximum borrowing capacity	1,300,000,000	1,300,000,000					150,000,000		300,000,000		850,000,000	850,000,000		350,000,000	350,000,000	350,000,000	500,000,000	500,000,000	500,000,000
Federal funds rate plus per annum percentage							0.50%									0.50%
One month LIBOR rate plus percentage							1.00%
Debt to capital ratio				0.35				0.35
Statutory surplus				3,575,381,000				1,875,000,000
Minimum net worth consolidated net income percentage				25.00%				25.00%
Percentage of increase in consolidated net worth				25.00%				25.00%
Minimum net worth			$ 4,292,517,000		$ 1,898,936,000
Percentage of interest on the principal amount of letters of credit issued									0.20%
Principal amount of issued letters of credit expiry, months									15	60
Percentage of interest on the principal amount of issued extended tenor letters of credit									0.25%
Per annum commitment fee on undrawn credit									0.10%