Compensation Expense for Share-Based Payment Arrangements and Associated Tax Impacts (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	$ 77.7	$ 73.8	$ 73.9
Tax Benefits Recognized	29.1	27.7	27.7
Restricted Stock Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	52.9	48.0	44.0
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	12.8	18.4	27.4
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	$ 12.0	$ 7.4	$ 2.5