Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income tax expense or benefit	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Gross deferred tax assets	36.9		36.9
Valuation allowance for net deferred tax assets	28.1		28.1
Net deferred tax assets	8.8		8.8
Deferred tax liabilities	8.8		8.8
Short term deferred tax liabilities	1.0		1.0
Current net deferred tax liabilities	7.8	7.7	7.8	7.7	$ 8.0
Long term deferred tax assets	$ 7.8	$ 7.7	$ 7.8	$ 7.7	$ 8.0