Share-Based Compensation Plans - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonqualified stock option grants	1,730,049
Stock options granted, total grant-date fair value	$ 20.0
Share-Based Compensation Expense	24.2	22.8
Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock unit awards granted	960,717
Stock unit awards, total grant-date fair value	41.9
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock unit awards granted	198,552
Stock unit awards, total grant-date fair value	8.7
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	11.2	14.9
Stock Options | Retirement Eligible Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	5.3	9.1
Stock and Stock Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	12.7	7.9
Stock and Stock Unit Awards | Fully Vested RSU Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Expense	$ 2.3