Quarterly report pursuant to Section 13 or 15(d)

Marketable Securities and Fair Value Measurements - Summary of Company's Available-for-Sale Securities (Detail)

v3.19.1
Marketable Securities and Fair Value Measurements - Summary of Company's Available-for-Sale Securities (Detail) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]    
Fair Value $ 45,720 $ 10,234
Cash Equivalents - Money Market Funds, Commercial Paper and Corporate Bonds    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 36,842  
Unrealized Gain 0  
Unrealized Loss 0  
Fair Value 36,842  
Marketable Securities, Current - Commercial Paper, Treasury Bills and Corporate Bonds    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis 45,720  
Unrealized Gain 0  
Unrealized Loss 0  
Fair Value $ 45,720  
Maturity Dates 2019-07  
Maturity Dates 2019-12  
Cash Equivalents - Money Market Funds and Commercial Paper    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis   85,434
Unrealized Gain   0
Unrealized Loss   0
Fair Value   85,434
Marketable Securities, Current - Commercial Paper    
Schedule Of Available For Sale Securities [Line Items]    
Cost Basis   10,234
Unrealized Gain   0
Unrealized Loss   0
Fair Value   $ 10,234
Maturity Dates   2019-01
Maturity Dates   2019-09