Other Income, Net - Schedule of Components of Other Income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Securities earnings:
Dividends and interest			$ 13.1	$ 14.1
Securities transactions, net			0.2	0.1
Total	6.7	7.1	13.3	14.2
Equity in earnings of investees	(0.5)	(0.1)	(0.8)
Currency transactions, net			(1.2)	0.5
Insurance recoveries	1.0	0.3	1.6	1.4
Litigation settlement gain		14.7		14.7
Other, net			0.2	1.0
Total	$ 4.3	$ 22.2	$ 13.1	$ 31.8