Annual report pursuant to Section 13 and 15(d)

Investments - Schedule of Available for Sale Securities Reconciliation (Details)

v3.20.1
Investments - Schedule of Available for Sale Securities Reconciliation (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2018
USD ($)
Debt Securities, Available-for-sale [Line Items]  
Cost $ 4,572
Unrealized Gain 1
Unrealized Loss (48)
Fair Value 4,525
Short-term Investments [Member]  
Debt Securities, Available-for-sale [Line Items]  
Cost 393
Unrealized Gain 1
Unrealized Loss
Fair Value 394
Short-term Investments [Member] | U.S. Treasury Notes [Member]  
Debt Securities, Available-for-sale [Line Items]  
Cost 302
Unrealized Gain 1
Unrealized Loss
Fair Value 303
Short-term Investments [Member] | Corporate Bonds and Commercial Paper [Member]  
Debt Securities, Available-for-sale [Line Items]  
Cost 91
Unrealized Gain
Unrealized Loss
Fair Value 91
Long-term Investments [Member]  
Debt Securities, Available-for-sale [Line Items]  
Cost 4,179
Unrealized Gain
Unrealized Loss (48)
Fair Value 4,131
Long-term Investments [Member] | U.S. Treasury Notes [Member]  
Debt Securities, Available-for-sale [Line Items]  
Cost 1,569
Unrealized Gain
Unrealized Loss (2)
Fair Value 1,567
Long-term Investments [Member] | Government Agency Bonds [Member]  
Debt Securities, Available-for-sale [Line Items]  
Cost 1,548
Unrealized Gain
Unrealized Loss (23)
Fair Value 1,525
Long-term Investments [Member] | Corporate Bonds [Member]  
Debt Securities, Available-for-sale [Line Items]  
Cost 1,062
Unrealized Gain
Unrealized Loss (23)
Fair Value $ 1,039