Subsequent events - Loan Margins and Commitment Fee Rates (Details) - Subsequent Event	Oct. 29, 2021
Subsequent Event [Line Items]
Commitment fee rate	0.30%
Debt Covenant, Range One
Subsequent Event [Line Items]
Commitment fee rate	0.30%
Debt Covenant, Range One | Minimum
Subsequent Event [Line Items]
Debt instrument, leverage ratio	2.50
Debt Covenant, Range Two
Subsequent Event [Line Items]
Commitment fee rate	0.25%
Debt Covenant, Range Two | Minimum
Subsequent Event [Line Items]
Debt instrument, leverage ratio	1.50
Debt Covenant, Range Two | Maximum
Subsequent Event [Line Items]
Debt instrument, leverage ratio	2.50
Debt Covenant, Range Three
Subsequent Event [Line Items]
Commitment fee rate	0.20%
Debt Covenant, Range Three | Minimum
Subsequent Event [Line Items]
Debt instrument, leverage ratio	0.75
Debt Covenant, Range Three | Maximum
Subsequent Event [Line Items]
Debt instrument, leverage ratio	1.50
Debt Covenant, Range Four
Subsequent Event [Line Items]
Commitment fee rate	0.15%
Debt Covenant, Range Four | Maximum
Subsequent Event [Line Items]
Debt instrument, leverage ratio	0.75
Eurodollar
Subsequent Event [Line Items]
Debt instrument, lending margin, interest rate	2.00%
Eurodollar | Debt Covenant, Range One
Subsequent Event [Line Items]
Debt instrument, lending margin, interest rate	2.00%
Eurodollar | Debt Covenant, Range Two
Subsequent Event [Line Items]
Debt instrument, lending margin, interest rate	1.75%
Eurodollar | Debt Covenant, Range Three
Subsequent Event [Line Items]
Debt instrument, lending margin, interest rate	1.50%
Eurodollar | Debt Covenant, Range Four
Subsequent Event [Line Items]
Debt instrument, lending margin, interest rate	1.25%
BR | Debt Covenant, Range One
Subsequent Event [Line Items]
Debt instrument, lending margin, interest rate	1.00%
BR | Debt Covenant, Range Two
Subsequent Event [Line Items]
Debt instrument, lending margin, interest rate	0.75%
BR | Debt Covenant, Range Three
Subsequent Event [Line Items]
Debt instrument, lending margin, interest rate	0.50%
BR | Debt Covenant, Range Four
Subsequent Event [Line Items]
Debt instrument, lending margin, interest rate	0.25%