Other income, net - Schedule of Components of Other Income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Securities earnings:
Dividends and interest		$ 28.4	$ 29.2	$ 26.0
Securities transactions, net		21.8	(0.6)	0.3
Total		50.2	28.6	26.3
Equity in joint venture earnings		(0.2)	(0.5)	(0.4)
Insurance recoveries	8.7	3.3	16.9	18.8
Currency transactions, net		(1.0)	3.0	7.8
Disposal of property and equipment, net		1.5	(0.9)	(1.8)
Litigation settlement gains		14.7		6.3
Other, net		2.1	1.8	1.9
Total		$ 70.6	$ 49.0	$ 58.9