Long-term debt outstanding (Details 2) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Long-term debt outstanding [Line Items]
Long-term debt	$ 2,847,068	$ 2,841,425	$ 2,747,763
Long-term debt due within one year	78,031	78,031	147,953
Long-term debt	$ 2,769,037	2,763,394	2,599,810
Senior Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	4.32%
Long-term debt	$ 2,258,500	2,258,500	2,275,000
Commercial Paper
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	6.18%
Long-term debt	$ 462,600	415,500	348,500
Medium-term Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	7.32%
Long-term debt	$ 35,000	35,000	35,000
Credit Agreements
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	8.04%
Long-term debt	$ 89,144	130,000	85,800
Term Loan Agreements
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	3.64%
Long-term debt	$ 7,000	7,000	7,700
Other Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	1.43%
Long-term debt	$ 1,561	2,253	2,445
Long-term Debt
Long-term debt outstanding [Line Items]
Unamortized Debt Issuance Costs	6,453	6,542	6,605
Discount	$ 284	$ 286	$ 77