SCHEDULE V VALUATION AND QUALIFYING ACCOUNTS (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Reinsurance recoverable on paid losses: Allowance for reinsurance balances
VALUATION AND QUALIFYING ACCOUNTS
Balance at beginning of period	$ 34.4		$ 29.4		$ 30.0
Charged to costs and expenses	(0.6)		8.5		(0.4)
Charged to other accounts	0		0		0
Deductions described	1.7	[1]	(3.5)	[1]	(0.2)	[1]
Balance at end of period	35.5		34.4		29.4
Property and casualty insurance and reinsurance premiums receivable: Allowance for uncollectible accounts
VALUATION AND QUALIFYING ACCOUNTS
Balance at beginning of period	3.4		3.9		6.3
Charged to costs and expenses	1.1		0		0.2
Charged to other accounts	0		(0.5)		(1.0)
Deductions described	(0.1)	[1]	0	[1]	(1.6)	[1]
Balance at end of period	$ 4.4		$ 3.4		$ 3.9

[1] Represents net collections (charge-offs) of balances receivables and foreign currency translation.