Income Taxes - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($)
Income Tax Disclosure [Line Items]
Deferred tax assets, net	$ 16.3
Research and development tax credit studies	11.1
Unrecognized tax benefits	2.4
Deferred tax assets, valuation allowance	$ 0.4
Overall effective tax rate, after discrete period adjustments	44.00%
Effective tax rate, before discrete period adjustment	45.50%
Research and Development Credits
Income Tax Disclosure [Line Items]
Tax credit carryforward, valuation allowance	$ 1.2
Expiring in 2019
Income Tax Disclosure [Line Items]
Tax credit carryforward, amount	1.2
Federal
Income Tax Disclosure [Line Items]
Unrecognized tax benefits	2.3
State
Income Tax Disclosure [Line Items]
Unrecognized tax benefits	$ 0.1