REINSURANCE (Tables)

12 Months Ended

Dec. 31, 2011

Schedule Of Reinsurance Premiums Written And Earned [Text Block]

	Premiums Written Year Ended December 31,									Premiums Earned Year Ended December 31,
(U.S. dollars in thousands)	2011			2010			2009			2011			2010			2009
Direct	$	4,714,588		$	4,398,753		$	4,381,185		$	4,624,557		$	4,535,626		$	4,861,073
Assumed		2,183,696			1,862,578			1,730,126			2,179,555			1,837,528			1,877,634
Ceded		(1,464,896	)		(1,261,743	)		(1,367,599	)		(1,477,000	)		(1,342,017	)		(1,586,968	)
Net	$	5,433,388		$	4,999,588		$	4,743,712		$	5,327,112		$	5,031,137		$	5,151,739

Analysis Of Unpaid Losses And Loss Expenses And Future Policy Benefit Reserves Recoverable [Text Block]

(U.S. dollars in thousands)	2011		2010
P&C operations	$	3,629,928	$	3,649,290
Life operations		25,020		22,597
Total unpaid losses and loss expenses recoverable	$	3,654,948	$	3,671,887

Analysis Of Total Recoverable And Reinsurance Balances Receivable By Reinsurers Owing More Than 3 Percentage [Text Block]

Name of reinsurer	Reinsurer Financial Strength Rating	% of total
Munich Reinsurance Company	AA-/Stable		22.8	%
Swiss Reinsurance Company	AA-/Stable		12.2	%
Swiss Re Europe S.A.	AA-/Stable		5.1	%
Transatlantic Reinsurance Company	A+/Stable		3.7	%
Everest Reinsurance Company	A+/Stable		3.0	%

Ratings Profile Of Reinsurers [Text Block]

Reinsurer Financial Strength Rating	% of total
AAA		1.3	%
AA		58.4	%
A		32.3	%
BBB		0.4	%
BB and below		0.1	%
Captives		4.8	%
Not Rated		0.2	%
Other		2.5	%
Total		100.0	%