Debt and Financing Arrangements Debt Disclosure (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	May 08, 2020
Debt Instrument [Line Items]
Total long-term debt, including current portion	$ 5,338,624,000	$ 5,286,643,000
Other financing obligation	1,156,124,000	1,104,143,000
Unamortized debt issuance costs	(30,393,000)	(32,505,000)
Unamortized debt premium and discount, net	(13,613,000)	(14,358,000)
Long-term debt due within one year	25,594,000	22,640,000
Total long-term debt	5,269,024,000	5,217,140,000
Advances for construction costs	0	38,585,000
Long-term Debt, Fiscal Year Maturity [Abstract]
2022	25,594,000
2023	28,029,000
2024	30,701,000
2025	33,630,000
2026	$ 1,244,343,000
7.08% due 2026 [Member]
Debt Instrument [Line Items]
Long-term debt interest rate	7.08%
7.25% due 2026 [Member]
Debt Instrument [Line Items]
Long-term debt interest rate	7.25%
7.85% due 2026
Debt Instrument [Line Items]
Long-term debt interest rate	7.85%
4.0% due 2028 [Member]
Debt Instrument [Line Items]
Long-term debt interest rate	4.00%
3.25% due 2030 [Member]
Debt Instrument [Line Items]
Long-term debt face amount			$ 700,000,000
Long-term debt interest rate	3.25%		3.25%
5.4% due 2041 [Member]
Debt Instrument [Line Items]
Long-term debt interest rate	5.40%
4.45% due 2042 [Member]
Debt Instrument [Line Items]
Long-term debt interest rate	4.45%
4.6 % due 2048 [Member]
Debt Instrument [Line Items]
Long-term debt interest rate	4.60%
3.95 due 2050 [Member]
Debt Instrument [Line Items]
Long-term debt face amount			$ 500,000,000
Long-term debt interest rate	3.95%		3.95%
Dalton Expansion Project [Member]
Debt Instrument [Line Items]
Long-term debt face amount	$ 251,900,000	254,400,000
Other Long-term Debt, Current	2,500,000	2,300,000
Atlantic Sunrise Project [Member]
Debt Instrument [Line Items]
Other financing obligation	807,100,000	827,100,000
Additions to other financing obligations	2,600,000	8,700,000
Other Long-term Debt, Current	22,400,000	20,300,000
Leidy South Project [Member]
Debt Instrument [Line Items]
Other financing obligation	71,500,000
Other Long-term Debt, Current	700,000
Advances for construction costs	$ 72,000,000
Long-term Debt, Term	20 years
Property pledged as collateral
Debt Instrument [Line Items]
Total long-term debt	$ 0
9% Other Financing Obligations due 2052 [Member]
Debt Instrument [Line Items]
Long-term debt interest rate	9.00%
9% Other Financing Obligations due 2038 [Member]
Debt Instrument [Line Items]
Long-term debt interest rate	9.00%
16% Other Financing Obligations due 2041 [Member]
Debt Instrument [Line Items]
Long-term debt interest rate	16.00%
Debentures
Debt Instrument [Line Items]
Total long-term debt, including current portion	$ 207,500,000	207,500,000
Debentures | 7.08% due 2026 [Member]
Debt Instrument [Line Items]
Total long-term debt, including current portion	7,500,000	7,500,000
Debentures | 7.25% due 2026 [Member]
Debt Instrument [Line Items]
Total long-term debt, including current portion	200,000,000	200,000,000
Notes
Debt Instrument [Line Items]
Total long-term debt, including current portion	3,975,000,000	3,975,000,000
Notes | 7.85% due 2026
Debt Instrument [Line Items]
Total long-term debt, including current portion	1,000,000,000	1,000,000,000
Notes | 4.0% due 2028 [Member]
Debt Instrument [Line Items]
Total long-term debt, including current portion	400,000,000	400,000,000
Notes | 3.25% due 2030 [Member]
Debt Instrument [Line Items]
Total long-term debt, including current portion	700,000,000	700,000,000
Notes | 5.4% due 2041 [Member]
Debt Instrument [Line Items]
Total long-term debt, including current portion	375,000,000	375,000,000
Notes | 4.45% due 2042 [Member]
Debt Instrument [Line Items]
Total long-term debt, including current portion	400,000,000	400,000,000
Notes | 4.6 % due 2048 [Member]
Debt Instrument [Line Items]
Total long-term debt, including current portion	600,000,000	600,000,000
Notes | 3.95 due 2050 [Member]
Debt Instrument [Line Items]
Total long-term debt, including current portion	$ 500,000,000	$ 500,000,000