Fair Value Measurements Table - Fair Value of Financial Assets and Liabilities (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Price Risk Derivative Assets, at Fair Value	$ 700	$ 384
Other Assets, Fair Value Disclosure	26	31
Assets, Fair Value Disclosure	726	415
Interest Rate Derivative Liabilities, at Fair Value	(573)	(399)
Price Risk Derivative Liabilities, at Fair Value	(631)	(389)
Financial and Nonfinancial Liabilities, Fair Value Disclosure	(1,204)	(788)
Level 1
Price Risk Derivative Assets, at Fair Value	677	369
Other Assets, Fair Value Disclosure	17	20
Assets, Fair Value Disclosure	694	389
Interest Rate Derivative Liabilities, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	(620)	(383)
Financial and Nonfinancial Liabilities, Fair Value Disclosure	(620)	(383)
Level 2
Price Risk Derivative Assets, at Fair Value	23	15
Other Assets, Fair Value Disclosure	9	11
Assets, Fair Value Disclosure	32	26
Interest Rate Derivative Liabilities, at Fair Value	(573)	(399)
Price Risk Derivative Liabilities, at Fair Value	(11)	(6)
Financial and Nonfinancial Liabilities, Fair Value Disclosure	(584)	(405)
Commodity Derivatives - Natural Gas [Member] | Basis Swaps IFERC/NYMEX [Member]
Price Risk Derivative Assets, at Fair Value	108	17
Price Risk Derivative Liabilities, at Fair Value	(85)	(49)
Commodity Derivatives - Natural Gas [Member] | Swing Swaps IFERC [Member]
Price Risk Derivative Assets, at Fair Value	2	1
Price Risk Derivative Liabilities, at Fair Value	(2)	(1)
Commodity Derivatives - Natural Gas [Member] | Fixed Swaps/Futures [Member]
Price Risk Derivative Assets, at Fair Value	31	65
Price Risk Derivative Liabilities, at Fair Value	(33)	(43)
Commodity Derivatives - Natural Gas [Member] | Forward Physical Swaps [Member]
Price Risk Derivative Assets, at Fair Value	6	3
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	108	17
Price Risk Derivative Liabilities, at Fair Value	(85)	(49)
Commodity Derivatives - Natural Gas [Member] | Level 1 | Swing Swaps IFERC [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	(1)	0
Commodity Derivatives - Natural Gas [Member] | Level 1 | Fixed Swaps/Futures [Member]
Price Risk Derivative Assets, at Fair Value	31	65
Price Risk Derivative Liabilities, at Fair Value	(33)	(43)
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 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	2	1
Price Risk Derivative Liabilities, at Fair Value	(1)	(1)
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	6	3
Price Risk Derivative Liabilities, at Fair Value	(1)
Commodity Derivatives - Refined Products [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value		8
Price Risk Derivative Liabilities, at Fair Value	(7)	(10)
Commodity Derivatives - Refined Products [Member] | Level 1 | Future [Member]
Price Risk Derivative Assets, at Fair Value		8
Price Risk Derivative Liabilities, at Fair Value	(7)	(10)
Commodity Derivatives - Refined Products [Member] | Level 2 | Future [Member]
Price Risk Derivative Assets, at Fair Value		0
Price Risk Derivative Liabilities, at Fair Value	0	0
Commodity Derivatives - Crude [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value	3
Commodity Derivatives - Crude [Member] | Forwards Swaps [Member]
Price Risk Derivative Assets, at Fair Value		13
Commodity Derivatives - Crude [Member] | Level 1 | Future [Member]
Price Risk Derivative Assets, at Fair Value	3
Commodity Derivatives - Crude [Member] | Level 1 | Forwards Swaps [Member]
Price Risk Derivative Assets, at Fair Value		13
Commodity Derivatives - Crude [Member] | Level 2 | Future [Member]
Price Risk Derivative Assets, at Fair Value	0
Commodity Derivatives - Crude [Member] | Level 2 | Forwards Swaps [Member]
Price Risk Derivative Assets, at Fair Value		0
Commodity Derivatives - Power [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	15	11
Price Risk Derivative Liabilities, at Fair Value	(9)	(5)
Commodity Derivatives - Power [Member] | Put Option [Member]
Price Risk Derivative Assets, at Fair Value	2	1
Commodity Derivatives - Power [Member] | Call Option [Member]
Price Risk Derivative Assets, at Fair Value	1	1
Commodity Derivatives - Power [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value	5	4
Price Risk Derivative Liabilities, at Fair Value	(5)	(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	0
Commodity Derivatives - Power [Member] | Level 1 | Put Option [Member]
Price Risk Derivative Assets, at Fair Value	2	1
Commodity Derivatives - Power [Member] | Level 1 | Call Option [Member]
Price Risk Derivative Assets, at Fair Value	1	1
Commodity Derivatives - Power [Member] | Level 1 | Future [Member]
Price Risk Derivative Assets, at Fair Value	5	4
Price Risk Derivative Liabilities, at Fair Value	(5)	(3)
Commodity Derivatives - Power [Member] | Level 2 | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	15	11
Price Risk Derivative Liabilities, at Fair Value	(9)	(5)
Commodity Derivatives - Power [Member] | Level 2 | Put Option [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Commodity Derivatives - Power [Member] | Level 2 | Call Option [Member]
Price Risk Derivative Assets, at Fair Value	0	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	527	260
Price Risk Derivative Liabilities, at Fair Value	(489)	(278)
Commodity Derivatives - NGLs [Member] | Level 1 | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	527	260
Price Risk Derivative Liabilities, at Fair Value	(489)	(278)
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