Fair Value of Financial Instruments - Summary of Financial Assets Measured at Fair Value on Recurring Basis (Detail) - Fair Value - Fair Value, Measurements, Recurring $ in Thousands	Dec. 31, 2018 USD ($)
Assets:
Fair value measurement disclosure	$ 31,153
Certificates of deposit
Assets:
Fair value measurement disclosure	31,153
Level 1
Assets:
Fair value measurement disclosure	0
Level 1 | Certificates of deposit
Assets:
Fair value measurement disclosure	0
Level 2
Assets:
Fair value measurement disclosure	31,153
Level 2 | Certificates of deposit
Assets:
Fair value measurement disclosure	31,153
Level 3
Assets:
Fair value measurement disclosure	0
Level 3 | Certificates of deposit
Assets:
Fair value measurement disclosure	$ 0