SCHEDULE V VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reinsurance recoverable on paid losses: Allowance for reinsurance balances
VALUATION AND QUALIFYING ACCOUNTS
Balance at beginning of period	$ 0.7	$ 2.2	$ 14.3
Charged to costs and expenses	(0.2)	0.1	0.5
Charged to other accounts (1)	0.0	0.0	0.0
Deductions described	0.0	(1.4)	(11.6)
Balance at end of period	0.9	0.7	2.2
Property and casualty insurance and reinsurance premiums receivable: Allowance for uncollectible accounts
VALUATION AND QUALIFYING ACCOUNTS
Balance at beginning of period	2.0	1.9	3.1
Charged to costs and expenses	0.3	(0.8)	(0.2)
Charged to other accounts (1)	(0.4)	(0.7)	(1.0)
Deductions described	0.0	0.0	0.0
Balance at end of period	$ 1.3	$ 2.0	$ 1.9