Quarterly report pursuant to Section 13 or 15(d)

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

v3.8.0.1
Investments and Fair Value Measurements - Category of Financial Instruments Not Held at Fair Value (Parenthetical) (Detail) - Level 1 - USD ($)
$ in Thousands
Mar. 31, 2018
Dec. 31, 2017
Carrying Amount    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Cash equivalents $ 17,000 $ 16,500
Fair Value    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Cash equivalents $ 17,000 $ 16,500