Income Taxes (Reconciliation Of Difference Between Provision (Benefit) For Income Taxes And Expected Tax Provision (Benefit) At Weighted Average Tax Rate) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Income Tax Examination [Line Items]
Income tax provision at expected rate	$ 3.3	$ 7.5	$ 17.0	$ 17.1
Tax-exempt interest	(1.2)	(1.4)	(4.2)	(4.3)
Dividends received deduction	(0.4)	(0.1)	(1.3)	(1.2)
Valuation allowance change	0.7	(0.2)	1.8	(0.7)
Other permanent adjustments, net	0.1	0.9	0.8	1.8
Adjustment for annualized rate	0	0.9	0	(0.1)
United States state tax expense (benefit)	0	0.1	(0.2)	(0.3)
Other foreign adjustments	0	(0.1)	0.1	0
Prior year foreign taxes recovered	0	(0.3)	0	(0.3)
Deferred tax rate reduction	(0.6)	(0.1)	(0.6)	(0.1)
Foreign exchange adjustments	2.4	(0.4)	0.4	1.4
Income tax provision	4.3	6.8	13.8	13.3
Income tax provision	4.3	6.8	13.8	13.3
Foreign Country [Member]
Income Tax Examination [Line Items]
Income tax provision	1.8	0.5	3.4	(5.5)
Income tax provision	1.8	0.5	3.4	(5.5)
United States Federal
Income Tax Examination [Line Items]
Income tax provision	2.3	6.0	10.6	19.2
Income tax provision	2.3	6.0	10.6	19.2
United States State [Member]
Income Tax Examination [Line Items]
Income tax provision	0.2	0.3	(0.2)	(0.4)
Income tax provision	$ 0.2	$ 0.3	$ (0.2)	$ (0.4)