Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Additional Information (Details)

v3.19.2
Fair Value Measurements - Additional Information (Details)
$ / shares in Units, $ in Thousands
 6 Months Ended
Jun. 30, 2019
USD ($)
$ / shares
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Investments, Fair Value Disclosure $ 11,193
Caelum [Member]  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Investments, Fair Value Disclosure $ 11,193
Measurement Input, Risk Free Interest Rate [Member] | Caelum [Member]  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Fair Values Assumptions Risk Free Return 2.24%
Measurement Input Investments [Member] | Caelum [Member]  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Investments, Fair Value Disclosure $ 11,200
Measurement Input, Share Price [Member] | Caelum [Member]  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Fair Values Assumptions Share Price | $ / shares $ 1.549
Measurement Input, Price Volatility [Member] | Caelum [Member]  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Fair Values Assumptions Expected Volatility Rate 70.00%
Fair Values Assumptions Expected Discount For Lack Of Marketability 27.90%