Recently Issued Accounting Standards - Schedule of Impact on Consolidated Statement of Cash Flows (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Prior to Adoption of Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net Cash provided by Operating Activities	$ 463.7	$ 967.7
Net Cash used in Financing Activities	(242.7)	(775.3)
Upon Adoption of Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net Cash provided by Operating Activities	470.5	980.8
Net Cash used in Financing Activities	$ (249.5)	$ (788.4)