Compensation Expense for Share-Based Payment Arrangements and Associated Tax Impacts (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	$ 19.2	$ 20.2	$ 42.1	$ 43.3
Tax Benefits Recognized	7.2	7.5	15.8	16.2
Restricted Stock Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	13.4	14.9	26.9	29.0
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	1.7	2.1	7.7	8.5
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	$ 4.1	$ 3.2	$ 7.5	$ 5.8