Stockholders' Equity (Estimated Amount of Total Share-based Compensation Expense) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012
Stock Based Compensation Activity [Line Items]
2012	$ 6.7	[1]
2013	15.9	[1]
2014	9.5	[1]
2015	1.6	[1]
Total	33.7	[1]
2012 Three-year PSU Awards [Member]
Stock Based Compensation Activity [Line Items]
2012	0.9
2013	3.7
2014	3.7
Total	8.3
2011 Three-year PSU Awards [Member]
Stock Based Compensation Activity [Line Items]
2012	0.6
2013	2.4
Total	3.0
2010 Three-year PSU Awards [Member]
Stock Based Compensation Activity [Line Items]
2012	0.9
Total	0.9
2012 CEO Incentive Compensation [Member]
Stock Based Compensation Activity [Line Items]
2012	1.1
Total	1.1
SLO Awards [Member]
Stock Based Compensation Activity [Line Items]
2012	0.2
2013	0.2
Total	0.4
Other long-term share-based incentive compensation programs [Member]
Stock Based Compensation Activity [Line Items]
2012	3.0
2013	9.6
2014	5.8
2015	1.6
Total	$ 20.0

[1] The amounts included above do not include the expense related to our U.S. profit sharing contributions made in the form of our common stock as such these contributions are not considered share-based incentive compensation.