Basis of Presentation and Significant Accounting Policies - Additional information (Detail) $ / shares in Units, $ in Millions			3 Months Ended			9 Months Ended		12 Months Ended
	Mar. 31, 2015 VEF / $	Nov. 24, 2014 $ / shares	Sep. 30, 2015 USD ($) $ / shares	Mar. 31, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) $ / shares	Sep. 30, 2014 USD ($)	Dec. 31, 2014 $ / shares VEF / $
Supplementary Information [Line Items]
Common stock, par value | $ / shares			$ 0.01			$ 0.01		$ 0.01
Stock-based compensation (income)/expense						$ 48.2	$ 40.7
Interest income			$ 0.6		$ 1.6	$ 1.8	4.4
Stock Split
Supplementary Information [Line Items]
Stock split additional shares issuable						One additional share of common stock for every two shares of common stock
Stock split conversion ratio		1.5
Common stock, par value | $ / shares		$ 0.01
Selling, general and administrative expenses
Supplementary Information [Line Items]
Stock-based compensation (income)/expense			$ 7.0		(0.3)	$ 48.2	40.7
Venezuela
Supplementary Information [Line Items]
Venezuela-related charges					$ 3.3	$ 60.6	$ 16.9
Impairment charge on non-monetary assets				$ 13.0
Foreign exchange-related charges				37.3
Venezuela | Official Rate
Supplementary Information [Line Items]
Foreign currency exchange rate | VEF / $								6.30
Venezuela | SICAD-II
Supplementary Information [Line Items]
Foreign currency exchange rate | VEF / $								50.0
Venezuela | SIMADI
Supplementary Information [Line Items]
Foreign currency exchange rate | VEF / $	193
Venezuela | Selling, general and administrative expenses
Supplementary Information [Line Items]
Venezuela-related charges				$ 60.6