Summary of Financial Instruments Carrying and Fair Values (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Mar. 01, 2032	Feb. 01, 2032	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Document Period End Date	Sep. 30, 2017
Investments, Fair Value Disclosure	$ 9.3			$ 9.2
Long-term debt, including current maturities	3,826.7			3,823.1
Long-term Debt, Fair Value	4,022.4			3,967.4
Derivative assets	19.3			110.2
Derivative liabilities	594.9			97.6
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments, Fair Value Disclosure	8.9			8.9
Long-term debt, including current maturities	3,826.7			3,823.1
Derivative assets	19.3			110.2
Derivative liabilities	$ 594.9			$ 97.6
Scenario, Forecast [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Business Combination, Contingent Consideration Percent of Sales, Liability, Noncurrent		3.00%
Business Combination, Contingent Consideration, Liability, Noncurrent			$ 84.0
Scenario, Forecast [Member] | Minimum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Business Combination, Contingent Consideration Percent of Sales, Liability, Noncurrent			2.50%
Scenario, Forecast [Member] | Maximum [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Business Combination, Contingent Consideration Percent of Sales, Liability, Noncurrent			3.50%