Annual report pursuant to Section 13 and 15(d)

FAIR VALUE MEASUREMENTS - Fair value of warrant liabilities (Details)

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FAIR VALUE MEASUREMENTS - Fair value of warrant liabilities (Details) - USD ($)
 9 Months Ended 12 Months Ended
Dec. 31, 2019
Dec. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Fair value as of beginning period $ 56,360,000
Initial measurement on July 1, 2019 38,110,000  
Change in valuation inputs or other assumptions 18,250,000 21,498,000
Fair value as of Ending period 56,360,000 77,858,000
Private Placement Warrants    
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Fair value as of beginning period 23,700,000
Initial measurement on July 1, 2019 15,800,000  
Change in valuation inputs or other assumptions 7,900,000 8,848,000
Fair value as of Ending period 23,700,000 32,548,000
Public Warrants    
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]    
Fair value as of beginning period 32,660,000
Initial measurement on July 1, 2019 22,310,000  
Change in valuation inputs or other assumptions 10,350,000 12,650,000
Fair value as of Ending period $ 32,660,000 $ 45,310,000