Compensation Expense for Share-Based Payment Arrangements and Associated Tax Impacts (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	$ 24.2	$ 22.8
Tax Benefits Recognized	9.1	8.5
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	11.2	14.9
Stock and Stock Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	12.7	7.9
Restricted Stock Units and Performance Stock Units[Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	$ 0.3