Fair Value Measurements Table - Fair Value of Financial Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Liabilities, Fair Value Disclosure, Recurring	$ (589)	$ (749)
Fair Value, Inputs, Level 1 [Member]
Liabilities, Fair Value Disclosure, Recurring	(341)	(551)
Fair Value, Inputs, Level 2 [Member]
Liabilities, Fair Value Disclosure, Recurring	(234)	(182)
Level 3 [Member]
Liabilities, Fair Value Disclosure, Recurring	(14)	(16)
Commodity Derivatives - Natural Gas [Member] | Forward Physical Swaps [Member]
Price Risk Derivative Assets, at Fair Value	1
Commodity Derivatives - Natural Gas [Member] | Fair Value, Inputs, Level 1 [Member] | Forward Physical Swaps [Member]
Price Risk Derivative Assets, at Fair Value	0
Commodity Derivatives - Natural Gas [Member] | Fair Value, Inputs, Level 2 [Member] | Forward Physical Swaps [Member]
Price Risk Derivative Assets, at Fair Value	1
Commodity Derivatives - Natural Gas [Member] | Level 3 [Member] | Forward Physical Swaps [Member]
Price Risk Derivative Assets, at Fair Value	0
Commodity Derivatives - Crude Oil [Member] | Future [Member]
Price Risk Derivative Liabilities, at Fair Value	(3)
Commodity Derivatives - Crude Oil [Member] | Fair Value, Inputs, Level 1 [Member] | Future [Member]
Price Risk Derivative Liabilities, at Fair Value	(3)
Commodity Derivatives - Crude Oil [Member] | Fair Value, Inputs, Level 2 [Member] | Future [Member]
Price Risk Derivative Liabilities, at Fair Value	0
Commodity Derivatives - Crude Oil [Member] | Level 3 [Member] | Future [Member]
Price Risk Derivative Liabilities, at Fair Value	0
Fair Value, Measurements, Recurring [Member]
Interest Rate Derivative Assets, at Fair Value	6	3
Price Risk Derivative Assets, at Fair Value	428	745
Assets, Fair Value Disclosure	434	748
Interest Rate Derivative Liabilities, at Fair Value	(226)	(155)
Embedded Derivative, Fair Value of Embedded Derivative Liability	(14)	(16)
Price Risk Derivative Liabilities, at Fair Value	(349)	(578)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Interest Rate Derivative Assets, at Fair Value	0	0
Price Risk Derivative Assets, at Fair Value	346	632
Assets, Fair Value Disclosure	346	632
Interest Rate Derivative Liabilities, at Fair Value	0	0
Embedded Derivative, Fair Value of Embedded Derivative Liability	0	0
Price Risk Derivative Liabilities, at Fair Value	(341)	(551)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Interest Rate Derivative Assets, at Fair Value	6	3
Price Risk Derivative Assets, at Fair Value	82	113
Assets, Fair Value Disclosure	88	116
Interest Rate Derivative Liabilities, at Fair Value	(226)	(155)
Embedded Derivative, Fair Value of Embedded Derivative Liability	0	0
Price Risk Derivative Liabilities, at Fair Value	(8)	(27)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Interest Rate Derivative Assets, at Fair Value	0	0
Price Risk Derivative Assets, at Fair Value	0	0
Assets, Fair Value Disclosure	0	0
Interest Rate Derivative Liabilities, at Fair Value	0	0
Embedded Derivative, Fair Value of Embedded Derivative Liability	(14)	(16)
Price Risk Derivative Liabilities, at Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Condensate [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	35	36
Price Risk Derivative Liabilities, at Fair Value	(1)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Condensate [Member] | Fair Value, Inputs, Level 1 [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Condensate [Member] | Fair Value, Inputs, Level 2 [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	35	36
Price Risk Derivative Liabilities, at Fair Value	(1)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Condensate [Member] | Level 3 [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Basis Swaps IFERC/NYMEX [Member]
Price Risk Derivative Assets, at Fair Value	11	19
Price Risk Derivative Liabilities, at Fair Value	(10)	(18)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Swing Swaps IFERC [Member]
Price Risk Derivative Assets, at Fair Value	2	26
Price Risk Derivative Liabilities, at Fair Value	(4)	(25)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Fixed Swaps/Futures [Member]
Price Risk Derivative Assets, at Fair Value	317	566
Price Risk Derivative Liabilities, at Fair Value	(293)	(490)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Forward Physical Swaps [Member]
Price Risk Derivative Assets, at Fair Value		1
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Fair Value, Inputs, Level 1 [Member] | Basis Swaps IFERC/NYMEX [Member]
Price Risk Derivative Assets, at Fair Value	11	19
Price Risk Derivative Liabilities, at Fair Value	(10)	(18)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Fair Value, Inputs, Level 1 [Member] | Swing Swaps IFERC [Member]
Price Risk Derivative Assets, at Fair Value	0	1
Price Risk Derivative Liabilities, at Fair Value	(1)	(2)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Fair Value, Inputs, Level 1 [Member] | Fixed Swaps/Futures [Member]
Price Risk Derivative Assets, at Fair Value	295	541
Price Risk Derivative Liabilities, at Fair Value	(293)	(490)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Fair Value, Inputs, Level 1 [Member] | Forward Physical Swaps [Member]
Price Risk Derivative Assets, at Fair Value		0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Fair Value, Inputs, Level 2 [Member] | Basis Swaps IFERC/NYMEX [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Fair Value, Inputs, Level 2 [Member] | Swing Swaps IFERC [Member]
Price Risk Derivative Assets, at Fair Value	2	25
Price Risk Derivative Liabilities, at Fair Value	(3)	(23)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed Swaps/Futures [Member]
Price Risk Derivative Assets, at Fair Value	22	25
Price Risk Derivative Liabilities, at Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Fair Value, Inputs, Level 2 [Member] | Forward Physical Swaps [Member]
Price Risk Derivative Assets, at Fair Value		1
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Level 3 [Member] | Basis Swaps IFERC/NYMEX [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Level 3 [Member] | Swing Swaps IFERC [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Level 3 [Member] | Fixed Swaps/Futures [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Natural Gas [Member] | Level 3 [Member] | Forward Physical Swaps [Member]
Price Risk Derivative Assets, at Fair Value		0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Refined Products [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value	7	21
Price Risk Derivative Liabilities, at Fair Value	(5)	(7)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Refined Products [Member] | Fair Value, Inputs, Level 1 [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value	7	21
Price Risk Derivative Liabilities, at Fair Value	(5)	(7)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Refined Products [Member] | Fair Value, Inputs, Level 2 [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Refined Products [Member] | Level 3 [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	5	3
Price Risk Derivative Liabilities, at Fair Value	(4)	(4)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Fixed Swaps/Futures [Member]
Price Risk Derivative Assets, at Fair Value	4
Price Risk Derivative Liabilities, at Fair Value	(3)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Put Option [Member]
Price Risk Derivative Liabilities, at Fair Value	(4)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Call Option [Member]
Price Risk Derivative Assets, at Fair Value	2
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value		4
Price Risk Derivative Liabilities, at Fair Value		(2)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Fair Value, Inputs, Level 1 [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Fair Value, Inputs, Level 1 [Member] | Fixed Swaps/Futures [Member]
Price Risk Derivative Assets, at Fair Value	4
Price Risk Derivative Liabilities, at Fair Value	(3)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Fair Value, Inputs, Level 1 [Member] | Put Option [Member]
Price Risk Derivative Liabilities, at Fair Value	(4)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Fair Value, Inputs, Level 1 [Member] | Call Option [Member]
Price Risk Derivative Assets, at Fair Value	2
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Fair Value, Inputs, Level 1 [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value		4
Price Risk Derivative Liabilities, at Fair Value		(2)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Fair Value, Inputs, Level 2 [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	5	3
Price Risk Derivative Liabilities, at Fair Value	(4)	(4)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed Swaps/Futures [Member]
Price Risk Derivative Assets, at Fair Value	0
Price Risk Derivative Liabilities, at Fair Value	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Fair Value, Inputs, Level 2 [Member] | Put Option [Member]
Price Risk Derivative Liabilities, at Fair Value	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Fair Value, Inputs, Level 2 [Member] | Call Option [Member]
Price Risk Derivative Assets, at Fair Value	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Fair Value, Inputs, Level 2 [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value		0
Price Risk Derivative Liabilities, at Fair Value		0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Level 3 [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Level 3 [Member] | Fixed Swaps/Futures [Member]
Price Risk Derivative Assets, at Fair Value	0
Price Risk Derivative Liabilities, at Fair Value	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Level 3 [Member] | Put Option [Member]
Price Risk Derivative Liabilities, at Fair Value	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Level 3 [Member] | Call Option [Member]
Price Risk Derivative Assets, at Fair Value	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Power [Member] | Level 3 [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value		0
Price Risk Derivative Liabilities, at Fair Value		0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - NGLs [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	42	69
Price Risk Derivative Liabilities, at Fair Value	(22)	(32)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - NGLs [Member] | Fair Value, Inputs, Level 1 [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	25	46
Price Risk Derivative Liabilities, at Fair Value	(22)	(32)
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - NGLs [Member] | Fair Value, Inputs, Level 2 [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	17	23
Price Risk Derivative Liabilities, at Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - NGLs [Member] | Level 3 [Member] | Forward Swaps [Member]
Price Risk Derivative Assets, at Fair Value	0	0
Price Risk Derivative Liabilities, at Fair Value	0	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Crude Oil [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value	2
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Crude Oil [Member] | Fair Value, Inputs, Level 1 [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value	2
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Crude Oil [Member] | Fair Value, Inputs, Level 2 [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value	0
Fair Value, Measurements, Recurring [Member] | Commodity Derivatives - Crude Oil [Member] | Level 3 [Member] | Future [Member]
Price Risk Derivative Assets, at Fair Value	$ 0