Fair Value Measurements Table - Fair Value of Financial Assets and Liabilities (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Price Risk Derivative Assets, at Fair Value	$ 1,034	$ 168
Other Assets, Fair Value Disclosure	37	34
Assets, Fair Value Disclosure	1,071	202
Interest Rate Derivative Liabilities, at Fair Value	(376)	(448)
Price Risk Derivative Liabilities, at Fair Value	(1,081)	(269)
Financial and Nonfinancial Liabilities, Fair Value Disclosure	(1,457)	(717)
Level 1
Price Risk Derivative Assets, at Fair Value	994	158
Other Assets, Fair Value Disclosure	24	22
Assets, Fair Value Disclosure	1,018	180
Interest Rate Derivative Liabilities, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	(1,059)	(265)
Financial and Nonfinancial Liabilities, Fair Value Disclosure	(1,059)	(265)
Level 2
Price Risk Derivative Assets, at Fair Value	40	10
Other Assets, Fair Value Disclosure	13	12
Assets, Fair Value Disclosure	53	22
Interest Rate Derivative Liabilities, at Fair Value	(376)	(448)
Price Risk Derivative Liabilities, at Fair Value	(22)	(4)
Financial and Nonfinancial Liabilities, Fair Value Disclosure	(398)	(452)
Commodity Derivatives - Natural Gas [Member] | Basis Swaps IFERC/NYMEX [Member]
Price Risk Derivative Assets, at Fair Value	14	12
Price Risk Derivative Liabilities, at Fair Value	(5)	(11)
Commodity Derivatives - Natural Gas [Member] | Swing Swaps IFERC [Member]
Price Risk Derivative Assets, at Fair Value	11	1
Price Risk Derivative Liabilities, at Fair Value	(7)	(3)
Commodity Derivatives - Natural Gas [Member] | Fixed Swaps/Futures [Member]
Price Risk Derivative Assets, at Fair Value	4	13
Price Risk Derivative Liabilities, at Fair Value	(78)	(13)
Commodity Derivatives - Natural Gas [Member] | Forward Physical Swaps [Member]
Price Risk Derivative Assets, at Fair Value	4	5
Price Risk Derivative Liabilities, at Fair Value	(1)
Commodity Derivatives - Natural Gas [Member] | Forward Physical Contracts [Member]
Price Risk Derivative Liabilities, at Fair Value		(1)
Commodity Derivatives - Natural Gas [Member] | Level 1 | Basis Swaps IFERC/NYMEX [Member]
Price Risk Derivative Assets, at Fair Value	14	12
Price Risk Derivative Liabilities, at Fair Value	(5)	(11)
Commodity Derivatives - Natural Gas [Member] | Level 1 | Swing Swaps IFERC [Member]
Price Risk Derivative Assets, at Fair Value	11	0
Price Risk Derivative Liabilities, at Fair Value	(7)	0
Commodity Derivatives - Natural Gas [Member] | Level 1 | Fixed Swaps/Futures [Member]
Price Risk Derivative Assets, at Fair Value	4	13
Price Risk Derivative Liabilities, at Fair Value	(78)	(13)
Commodity Derivatives - Natural Gas [Member] | Level 1 | Forward Physical Swaps [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0
Commodity Derivatives - Natural Gas [Member] | Level 1 | Forward Physical Contracts [Member]
Price Risk Derivative Liabilities, at Fair Value		0
Commodity Derivatives - Natural Gas [Member] | Level 2 | Basis Swaps IFERC/NYMEX [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0	0
Commodity Derivatives - Natural Gas [Member] | Level 2 | Swing Swaps IFERC [Member]
Price Risk Derivative Assets, at Fair Value	0	1
Price Risk Derivative Liabilities, at Fair Value	0	(3)
Commodity Derivatives - Natural Gas [Member] | Level 2 | Fixed Swaps/Futures [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0	0
Commodity Derivatives - Natural Gas [Member] | Level 2 | Forward Physical Swaps [Member]
Price Risk Derivative Assets, at Fair Value	4	5
Price Risk Derivative Liabilities, at Fair Value	(1)
Commodity Derivatives - Natural Gas [Member] | Level 2 | Forward Physical Contracts [Member]
Price Risk Derivative Liabilities, at Fair Value		(1)
Commodity Derivatives - Refined Products [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value	7	3
Price Risk Derivative Liabilities, at Fair Value	(10)	(11)
Commodity Derivatives - Refined Products [Member] | Level 1 | Future [Member]
Price Risk Derivative Assets, at Fair Value	7	3
Price Risk Derivative Liabilities, at Fair Value	(10)	(11)
Commodity Derivatives - Refined Products [Member] | Level 2 | Future [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0	0
Commodity Derivatives - Crude [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value	569
Price Risk Derivative Liabilities, at Fair Value	(582)
Commodity Derivatives - Crude [Member] | Level 1 | Future [Member]
Price Risk Derivative Assets, at Fair Value	569
Price Risk Derivative Liabilities, at Fair Value	(582)
Commodity Derivatives - Crude [Member] | Level 2 | Future [Member]
Price Risk Derivative Assets, at Fair Value	0
Price Risk Derivative Liabilities, at Fair Value	0
Commodity Derivatives - Power [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	36	4
Price Risk Derivative Liabilities, at Fair Value	(21)
Commodity Derivatives - Power [Member] | Call Option [Member]
Price Risk Derivative Assets, at Fair Value	1	1
Price Risk Derivative Liabilities, at Fair Value	(2)
Commodity Derivatives - Power [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value	4	2
Price Risk Derivative Liabilities, at Fair Value	(11)	(3)
Commodity Derivatives - Power [Member] | Level 1 | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0
Commodity Derivatives - Power [Member] | Level 1 | Call Option [Member]
Price Risk Derivative Assets, at Fair Value	1	1
Price Risk Derivative Liabilities, at Fair Value	(2)
Commodity Derivatives - Power [Member] | Level 1 | Future [Member]
Price Risk Derivative Assets, at Fair Value	4	2
Price Risk Derivative Liabilities, at Fair Value	(11)	(3)
Commodity Derivatives - Power [Member] | Level 2 | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	36	4
Price Risk Derivative Liabilities, at Fair Value	(21)
Commodity Derivatives - Power [Member] | Level 2 | Call Option [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0
Commodity Derivatives - Power [Member] | Level 2 | Future [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0	0
Commodity Derivatives - NGLs [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	384	127
Price Risk Derivative Liabilities, at Fair Value	(364)	(227)
Commodity Derivatives - NGLs [Member] | Level 1 | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	384	127
Price Risk Derivative Liabilities, at Fair Value	(364)	(227)
Commodity Derivatives - NGLs [Member] | Level 2 | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	$ 0	$ 0