Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Net operating loss carryforwards	$ 70.8	$ 66.2
Other accruals	5.6	4.8
Depreciation and amortization, including goodwill	0.4	0.3
Tax credit carryforward	0.5	0.5
Valuation allowance	(75.8)	(71.0)
Total deferred tax assets	1.5	0.8
Deferred tax liabilities:
Prepaid expenses	(1.7)	(0.9)
Total deferred tax liabilities	(1.7)	(0.9)
Net deferred tax liability	$ (0.2)	$ (0.1)