SEGMENT INFORMATION (Detail) - Net premiums written by geographical location (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
P&C Operations	$ 5,433,388	$ 4,999,588	$ 4,743,712
Life Operations:
Life Operations	362,362	382,075	532,852
Total	5,795,750	5,381,663	5,276,564
Bermuda [Member]
P&C Operations	572,825	561,514	545,965
Life Operations:
Life Operations	75,219	79,033	80,498
United States [Member]
P&C Operations	2,320,274	2,143,240	2,342,656
Life Operations:
Life Operations	0	0	31,478
Europe And Other [Member]
P&C Operations	2,540,289	2,294,834	1,855,091
Life Operations:
Life Operations	$ 287,143	$ 303,042	$ 420,876