Long-term debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Total principal long-term debt	$ 3,090,000	$ 3,256,000
Debt issuance costs	(30,295)	(31,378)
Unamortized premiums	7,078	7,348
Total long-term debt	3,066,783	3,231,970
Borrowings under revolving credit agreement expiring August 2024
Debt Instrument [Line Items]
Total principal long-term debt	$ 0	$ 166,000
Unsecured notes bearing fixed rate interest at 4.75% due March 2026 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate (as a percent)	0.0475%	0.0475%
Total principal long-term debt	$ 550,000	$ 550,000
Unsecured notes bearing fixed rate interest at 7.75% due June 2027 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate (as a percent)	0.0775%	0.0775%
Total principal long-term debt	$ 200,000	$ 200,000
Unsecured notes bearing fixed rate interest at 7.25% due September 2027 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate (as a percent)	0.0725%	0.0725%
Total principal long-term debt	$ 240,000	$ 240,000
Unsecured notes bearing fixed rate interest at 4.625% due March 2028 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate (as a percent)	0.04625%	0.04625%
Total principal long-term debt	$ 1,000,000	$ 1,000,000
Unsecured notes bearing fixed rate interest at 5.00% due September 2029 | Senior Notes
Debt Instrument [Line Items]
Stated interest rate (as a percent)	0.05%	0.05%
Total principal long-term debt	$ 1,100,000	$ 1,100,000