Derivative Instruments and Hedging Activities - Impact of Rights of Offset Associated with Recognized Assets and Liabilities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014
Current Asset [Member]
Derivative Instruments And Hedging Activities [Line Items]
Fair Value of Derivative Instruments, Assets	$ 0.7
Long-term assets [Member]
Derivative Instruments And Hedging Activities [Line Items]
Fair Value of Derivative Instruments, Assets	1.9
Current liabilities [Member]
Derivative Instruments And Hedging Activities [Line Items]
Fair Value of Derivative Instruments, Liabilities	(15.3)
Long-term liabilities [Member]
Derivative Instruments And Hedging Activities [Line Items]
Fair Value of Derivative Instruments, Liabilities	(0.4)
Effects of Netting [Member] | Current Asset [Member]
Derivative Instruments And Hedging Activities [Line Items]
Fair Value of Derivative Instruments, Assets	(0.7)
Effects of Netting [Member] | Long-term assets [Member]
Derivative Instruments And Hedging Activities [Line Items]
Fair Value of Derivative Instruments, Assets	(0.5)
Effects of Netting [Member] | Current liabilities [Member]
Derivative Instruments And Hedging Activities [Line Items]
Fair Value of Derivative Instruments, Liabilities	0.8
Effects of Netting [Member] | Long-term liabilities [Member]
Derivative Instruments And Hedging Activities [Line Items]
Fair Value of Derivative Instruments, Liabilities	0.4
With Effects of Netting [Member] | Current Asset [Member]
Derivative Instruments And Hedging Activities [Line Items]
Fair Value of Derivative Instruments, Assets
With Effects of Netting [Member] | Long-term assets [Member]
Derivative Instruments And Hedging Activities [Line Items]
Fair Value of Derivative Instruments, Assets	1.4
With Effects of Netting [Member] | Current liabilities [Member]
Derivative Instruments And Hedging Activities [Line Items]
Fair Value of Derivative Instruments, Liabilities	(14.5)
With Effects of Netting [Member] | Long-term liabilities [Member]
Derivative Instruments And Hedging Activities [Line Items]
Fair Value of Derivative Instruments, Liabilities