Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Assets and liabilities subject to fair value measurements
Commodity futures - financial assets	$ 5,597	$ 6,797
Commodity futures - financial liabilities	13,601	7,442
Long-term Debt.	3,105,876	3,102,676
Fair Value, Inputs, Level 2 [Member]
Assets and liabilities subject to fair value measurements
Fair value of long-term debt, including current maturities	3,300,000	3,400,000
Futures | Recurring | Commodity contract
Assets and liabilities subject to fair value measurements
Commodity futures - financial assets	5,597	6,797
Commodity futures - financial liabilities	13,601	7,442
Futures | Recurring | Fair Value, Inputs, Level 2 [Member] | Commodity contract
Assets and liabilities subject to fair value measurements
Commodity futures - financial assets	5,597	6,797
Commodity futures - financial liabilities	$ 13,601	$ 7,442