Changes in Level 3 Liabilities (Detail) (Other Liabilities, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Other Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value Liabilities Beginning Balance	$ 100.6	[1]	$ 58.6	[1]
Total (Gains) and Losses for the Period
Included in Earnings	2.3	[1]	(1.6)	[1]
Included in Other Comprehensive Income	0.4	[1]
Purchases, Issues, Sales, and Settlements
Issues	5.5	[1]	2.5	[1]
Settlements	(0.1)	[1]	(10.3)	[1]
Fair Value Liabilities Ending Balance	$ 108.7	[1]	$ 49.2	[1]

[1] Balances relate to standby letters of credit and contingent consideration liabilities.