Fair Value Measurements - Schedule of Reconciliation of the Beginning and Ending Level 3 Assets (Detail) - Unobservable Inputs (Level 3) [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	$ 5
Balance, end of period	5
Thera Warrant [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in the warrant in Thera	$ 0