Fair Value Measurements - Level 3 fair value measurements (Details) - Level 3	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	25.86	17.70	22.10
Share price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	9.95	9.88	10.02
Risk-free rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.87	0.92	0.36
Dividend yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.0	0.0	0.0