Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Accrued expenses	$ 3.2	$ 4.4
Accounts receivable	1.2	1.2
Net operating loss carryforward	123.6	124.0
Stock-based compensation	2.1	3.6
Intangible assets	8.0	8.0
Credits	1.0	1.0
Property and equipment	0.3
Other	2.9	1.1
Deferred Tax Assets Gross	142.3	143.3
Valuation allowance	(1.2)	(1.4)
Net deferred tax assets	141.1	141.9
Deferred tax liabilities:
Non-long lived intangible assets	(4.8)	(4.8)
Long-lived intangible assets	(77.7)	(62.2)
Property and equipment		(0.7)
Deferred state taxes	(0.7)	(1.7)
Net deferred tax liabilities	(83.2)	(69.4)
Deferred Assets Liabilities Net	$ 57.9	$ 72.5