Quarterly report pursuant to Section 13 or 15(d)

Fair Value of Financial Instruments - Hierarchy Table (Details)

v3.20.2
Fair Value of Financial Instruments - Hierarchy Table (Details) - USD ($)
$ in Thousands
6 Months Ended 12 Months Ended
Jun. 30, 2020
Dec. 31, 2019
Fair value    
Transfers between Level 2 and Level 3 $ 0 $ 0
Letter of credit collateral 1,300  
Adjusted cost    
Fair value    
Cash and Cash Equivalents, Fair Value Disclosure 10,663 9,302
Assets, Fair Value Disclosure 56,105 37,114
Fair Value    
Fair value    
Cash and Cash Equivalents, Fair Value Disclosure 10,663 9,302
Assets, Fair Value Disclosure 56,105 37,114
Cash and Cash Equivalents | Fair Value    
Fair value    
Cash and Cash Equivalents, Fair Value Disclosure 9,353 7,993
Assets, Fair Value Disclosure 54,795 32,305
Restricted Cash | Fair Value    
Fair value    
Cash and Cash Equivalents, Fair Value Disclosure 1,310 1,309
Assets, Fair Value Disclosure 1,310 1,309
Marketable Securities | Fair Value    
Fair value    
Assets, Fair Value Disclosure   3,500
Level 1 | Adjusted cost    
Fair value    
Investments, Fair Value Disclosure 45,442 24,302
Level 1 | Fair Value    
Fair value    
Investments, Fair Value Disclosure 45,442 24,302
Level 1 | Money market funds | Adjusted cost    
Fair value    
Investments, Fair Value Disclosure 45,442 18,306
Level 1 | Money market funds | Fair Value    
Fair value    
Investments, Fair Value Disclosure 45,442 18,306
Level 1 | U.S. treasury securities | Adjusted cost    
Fair value    
Investments, Fair Value Disclosure   5,996
Level 1 | U.S. treasury securities | Fair Value    
Fair value    
Investments, Fair Value Disclosure   5,996
Level 1 | Cash and Cash Equivalents | Fair Value    
Fair value    
Investments, Fair Value Disclosure 45,442 20,802
Level 1 | Cash and Cash Equivalents | Money market funds | Fair Value    
Fair value    
Investments, Fair Value Disclosure $ 45,442 18,306
Level 1 | Cash and Cash Equivalents | U.S. treasury securities | Fair Value    
Fair value    
Investments, Fair Value Disclosure   2,496
Level 1 | Marketable Securities | Fair Value    
Fair value    
Investments, Fair Value Disclosure   3,500
Level 1 | Marketable Securities | U.S. treasury securities | Fair Value    
Fair value    
Investments, Fair Value Disclosure   3,500
Level 2 | U.S. government agency securities | Adjusted cost    
Fair value    
Investments, Fair Value Disclosure   3,510
Level 2 | U.S. government agency securities | Fair Value    
Fair value    
Investments, Fair Value Disclosure   3,510
Level 2 | Cash and Cash Equivalents | U.S. government agency securities | Fair Value    
Fair value    
Investments, Fair Value Disclosure   $ 3,510