Quarterly report pursuant to Section 13 or 15(d)

FAIR VALUE MEASUREMENTS - Available-for-Sale Investments Included in Cash Equivalents (Details)

v3.19.2
FAIR VALUE MEASUREMENTS - Available-for-Sale Investments Included in Cash Equivalents (Details) - Cash and Cash Equivalents - USD ($)
$ in Thousands
Jun. 30, 2019
Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]    
Adjusted Cost $ 86,277 $ 85,363
Gross Unrealized Losses (22) (33)
Fair Value 86,255 85,330
Municipal bonds and notes    
Debt Securities, Available-for-sale [Line Items]    
Adjusted Cost 1,836 12,149
Gross Unrealized Losses 0 (7)
Fair Value 1,836 12,142
Corporate debt securities    
Debt Securities, Available-for-sale [Line Items]    
Adjusted Cost 45,294 51,862
Gross Unrealized Losses (22) (26)
Fair Value 45,272 51,836
Financial institution instruments    
Debt Securities, Available-for-sale [Line Items]    
Adjusted Cost 39,147 21,352
Gross Unrealized Losses 0 0
Fair Value $ 39,147 $ 21,352