Stockholders' Equity - Total Share-based Incentive Compensation Expense (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Total share-based incentive compensation expense	[1]	$ 15.9	$ 10.4	$ 49.1	$ 36.8

[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 or the expense or income related to SARs and other cash-based awards. See Stock Appreciation Rights above for further details of SARs. At September 30, 2015 and September 30, 2014, our other cash-based awards were not material to our condensed consolidated financial positions or results of operations.