Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Changes in Fair Value of Financial Instruments (Detail)

v3.19.1
Fair Value Measurements - Changes in Fair Value of Financial Instruments (Detail) - Caelum [Member]
$ in Thousands
3 Months Ended
Mar. 31, 2019
USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]  
Balance $ 10,905
Balance 0
Caelum Convertible Notes [Member]  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]  
Balance 9,914
Conversion of the convertible notes (9,914)
Balance $ 0