Long-term debt outstanding (Details 2) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Long-term debt outstanding [Line Items]
Long-term debt	$ 2,988,452	$ 2,741,900	$ 2,328,266
Long-term debt due within one year	214,453	148,053	1,548
Long-term debt	$ 2,773,999	2,593,847	2,326,718
Senior Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	4.29%
Long-term debt	$ 2,365,000	2,125,000	2,025,000
Commercial Paper
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	3.66%
Long-term debt	$ 460,600	450,300	168,800
Credit Agreements
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	4.55%
Long-term debt	$ 125,580	127,500	94,300
Medium-term Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	7.32%
Long-term debt	$ 35,000	35,000	35,000
Term Loan Agreements
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	3.64%
Long-term debt	$ 7,000	7,700	7,700
Other Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	0.97%
Long-term debt	$ 2,349	2,564	3,198
Long-term Debt
Long-term debt outstanding [Line Items]
Unamortized Debt Issuance Costs	6,633	6,090	5,709
Discount	$ 444	$ 74	$ 23