Short-Term Investments - Summary of Short-Term Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost		$ 6,928
Gross Unrealized Gains		0
Gross Unrealized Losses		(5)
Total short-term investments, Estimated Fair Value	$ 0	6,923
Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortized Cost		6,928
Gross Unrealized Gains		0
Gross Unrealized Losses		(5)
Total short-term investments, Estimated Fair Value		$ 6,923