Information Regarding Intrinsic Value of Stock Options Exercised and Stock Compensation Expense Related to Stock Option Awards (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic Value of Stock Options Exercised	$ 5.1	$ 4.2	$ 31.0	$ 38.2
Stock Compensation Expense Related to Stock Option Awards	1.9	1.6	13.3	9.3
Issued Stock Options	0	0	1.6	1.5
Weighted Average Fair Value of Stock Options issued (per share)	$ 11.31	$ 9.27	$ 10.90	$ 8.92
Fair Value of Stock Options Issued	$ 0.5	$ 0	$ 17.8	$ 13.7