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Long-Term Debt - By Issue (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Oct. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Long Term Debt
Total debt	$ 3,158,658			$ 2,764,472
Less debt issuance costs and original issue discounts	55,982			30,128
Long-term Debt, Total	3,102,676			2,734,344
Less current maturities	86,894			89,356
Long-term debt	3,015,782			2,644,988
2.800% senior notes due 2024
Long Term Debt
Total debt	$ 400,000			400,000
Stated interest rate	2.80%
2.400% senior notes due 2025
Long Term Debt
Total debt	$ 400,000
Stated interest rate	2.40%
1.650% senior notes due 2027
Long Term Debt
Total debt	$ 350,000
Stated interest rate	1.65%
5.000% senior notes due 2026
Long Term Debt
Total debt	$ 400,000			400,000
Stated interest rate	5.00%
3.450% senior notes due 2030
Long Term Debt
Total debt	$ 600,000			600,000
Stated interest rate	3.45%
3.250% senior notes due 2031
Long Term Debt
Total debt	$ 500,000
Stated interest rate	3.25%
3.250% senior notes due 2050
Long Term Debt
Total debt	$ 400,000
Stated interest rate	3.25%
5 1/4% Senior Notes due 2023
Long Term Debt
Total debt				$ 400,000
Stated interest rate				5.25%
5.500% senior notes due 2024
Long Term Debt
Total debt				$ 500,000
Stated interest rate			5.50%	5.50%
4.125% senior notes due 2025
Long Term Debt
Total debt				$ 350,000
Stated interest rate		4.125%		4.125%
Other obligations
Long Term Debt
Total debt	$ 108,658			$ 114,472
5.125% senior notes due 2021
Long Term Debt
Stated interest rate	5.125%