Assets and Liabilities Measured at Fair Value on Recurring Basis Based on Fair Value Hierarchy (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	$ 0.6	$ 0.2
Derivative liabilities as classified in the unaudited consolidated balance sheet	(0.4)	(0.9)
Common stock warrant liability, estimated fair value	(4.4)	(6.9)	$ (5.6)	$ (9.3)
Fair Value, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net derivative assets (liabilities)	0.2	(0.7)
Fair Value, Recurring | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	0.6	0.2
Derivative liabilities as classified in the unaudited consolidated balance sheet	(0.4)	(0.9)
Fair Value, Recurring | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Common stock warrant liability, estimated fair value	$ (4.4)	$ (6.9)