Financial Instruments - Effect of Company's Derivative Instruments on Net Income (Loss) (Detail) (Interest Rate Contracts [Member], Interest Expense [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Interest Rate Contracts [Member] | Interest Expense [Member]
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in OCI (Effective Portion)	$ (1.0)	$ 13.9	$ (8.3)