OTHER INVESTMENTS (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Restricted investments eligible for lockup	$ 240.0	$ 155.1
Restricted Investments, at Fair Value	28.4	38.8
Endorsements issued by third party on Directors and Officers policies			140
Purchase Of Payment Obligation From Third Party For Issuance Of Endorsement			150
Estimated Fair Value of Payment Obligation at Purchase Date			128.1
Coupon rate on outstanding payment obligation			3.50%
Face Value of Payment Obligation			150
Period of accretion of payment obligation			11.5
Fair Value of Other Asset Related to Payment Obligation			21.9
Fees Of Payment Obligations			2.5
Amortization Of Payment Obligation	9.4	9.5	5.5
Notes Payable, Fair Value Disclosure	147.5	147.3
Other than temporary impairment of other investments	0.7	7.8	0.9
Bermuda [Member]
Other Long Term Investments Structured Note Face Value			$ 155