Derivative Instruments (Details 2) (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Asset	[1]	$ 425	$ 392
Derivative Liability	[1]	516	316
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		67	26
Derivative Liability		21	31
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		358	366
Derivative Liability		495	285
Interest Rate Hedging Instruments
Derivatives, Fair Value [Line Items]
Derivative Asset		68	29
Derivative Liability		21	34
Interest Rate Hedging Instruments | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		67	26
Derivative Liability		21	31
Interest Rate Hedging Instruments | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		1	0
Derivative Liability		0	0
Energy Related Derivative [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset		357	366
Derivative Liability		$ 495	$ 285

[1] At March 31, 2018 and December 31, 2017, we had $206 million and $155 million of collateral under master netting arrangements that were not offset against our derivative instruments on the Consolidated Condensed Balance Sheets primarily related to initial margin requirements.