Quarterly report pursuant to Section 13 or 15(d)

Investments and Fair Value Measurements - Category of Financial Instruments Not Held at Fair Value (Detail)

v3.19.2
Investments and Fair Value Measurements - Category of Financial Instruments Not Held at Fair Value (Detail) - USD ($)
$ in Thousands
Jun. 30, 2019
Dec. 31, 2018
Carrying Amount    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Financial Assets, Investments $ 16 $ 1,493
Carrying Amount | Level I    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Financial Assets, Cash and cash equivalents 50,877 69,283
Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Financial Assets, Investments 16 1,493
Fair Value | Level I    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Financial Assets, Cash and cash equivalents $ 50,877 $ 69,283