Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Deferred Tax Valuation allowance increase	$ 17,400	$ 14,000
Federal [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	$ 210,400
Operating loss carryforwards, expiration date	Dec. 31, 2024
Federal [Member] | Research Tax Credit Carryforward
Income Taxes [Line Items]
Tax credit carryforwards	$ 2,900
Tax credit carryforwards, expiration date	Dec. 31, 2024
State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	$ 131,100
Tax credit carryforwards	$ 255
Operating loss carryforwards, expiration date	Dec. 31, 2019
Tax credit carryforwards, expiration date	Dec. 31, 2024