Long-term debt - Narrative (Details) - USD ($)		12 Months Ended
	Nov. 23, 2020	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2023	Sep. 28, 2020	Sep. 22, 2020
Debt Instrument [Line Items]
Debt issuance costs		$ 3,100,000
Debt issuance cost, amount paid to subsidiary		1,900,000
Debt issuance costs capitalized		1,200,000
Cash paid during the year for interest		68,399,000	$ 22,810,000	$ 10,089,000
5.50% Senior Secured Notes
Debt Instrument [Line Items]
Long-term debt gross		113,050,000	114,050,000
Debt instrument, repurchase amount			10,950,000
Interest expense, debt		6,200,000	6,800,000
Cash paid during the year for interest		6,200,000	$ 6,700,000
5.50% Senior Secured Notes | Senior Notes
Debt Instrument [Line Items]
Stated interest rate (as a percent)							5.50%
Aggregate principal amount of debt issued							$ 125,000,000
Issue price (as a percent)							100.00%
Redemption price (as a percent)	99.80%
Debt instrument, repurchase amount					$ 1,000,000
Notes outstanding		$ 113,050,000.00
6.75% Senior Secured Notes
Debt Instrument [Line Items]
Long-term debt gross						$ 150,000,000
Long term debt held in treasury						1,400,000
Long term debt outstanding, net of amount held in treasury						148,600,000
6.75% Senior Secured Notes | Senior Notes
Debt Instrument [Line Items]
Stated interest rate (as a percent)							6.75%
Long-term debt gross						$ 150,000,000