Income Taxes - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Income Taxes [Line Items]
Net operating loss carry forwards expiration	2036
Uncertain tax positions recognized	$ 0
Federal And State
Income Taxes [Line Items]
Net operating loss carryforwards	332,100
Federal Research And Development | Federal Tax
Income Taxes [Line Items]
Net operating loss carryforwards	$ 3,500