Financial Instruments - Effect of Company's Derivative Instruments on Net Income (Loss) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Interest Rate Products [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments, Gain (Loss) Recognized in OCI, (Effective Portion)	$ (2.2)	$ 10.9	$ (2.5)	$ 12.6
Interest Expense [Member]
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated OCI (Effective Portion)	$ (0.1)	$ (0.1)	$ (0.2)	$ (0.2)