Derivative Financial Instruments - Schedule of Derivative Instruments (Details) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Derivative Asset [Abstract]
Derivatives accounted for as cash flow hedges associated with debt:	[1]	$ 109	$ 97
Non-qualifying hedge activities:	[1]	0	20
Total Derivative Financial Assets	[1]	148	135
Less: Gross amounts offset in the balance sheet	[1],[2]	(148)	(135)
Net amounts of derivative financial assets and liabilities presented in the balance sheet	[1],[3]	0	0
Derivative Liability [Abstract]
Derivatives accounted for as cash flow hedges associated with debt:	[1]	(51)	(196)
Non-qualifying hedge activities:	[1]	0	(286)
Total Derivative Financial Liabilities	[1]	(251)	(683)
Less: Gross amounts offset in the balance sheet	[1],[2]	251	626
Net amounts of derivative financial assets and liabilities presented in the balance sheet	[1],[3]	0	(57)
Debt [Member]
Derivative Asset [Abstract]
Non-qualifying hedge activities:	[1]	39	18
Derivative Liability [Abstract]
Non-qualifying hedge activities:	[1]	(200)	(201)
Interest rate swaps [Member]
Derivative Asset [Abstract]
Derivatives accounted for as cash flow hedges associated with debt:	[1]	0	0
Non-qualifying hedge activities:	[1]	0	20
Derivative Liability [Abstract]
Derivatives accounted for as cash flow hedges associated with debt:	[1]	0	(18)
Non-qualifying hedge activities:	[1]	0	(286)
Interest rate swaps [Member] | Debt [Member]
Derivative Asset [Abstract]
Non-qualifying hedge activities:	[1]	0	4
Derivative Liability [Abstract]
Non-qualifying hedge activities:	[1]	0	0
Currency swaps [Member]
Derivative Asset [Abstract]
Derivatives accounted for as cash flow hedges associated with debt:	[1]	109	97
Derivative Liability [Abstract]
Derivatives accounted for as cash flow hedges associated with debt:	[1]	(51)	(178)
Currency swaps [Member] | Debt [Member]
Derivative Asset [Abstract]
Non-qualifying hedge activities:	[1]	39	14
Derivative Liability [Abstract]
Non-qualifying hedge activities:	[1]	$ (200)	$ (201)

[1] All of our derivatives are bilateral over-the-counter derivatives.

[2] Represents the netting of derivative receivable and payable balances for the same counterparty under an enforceable netting agreement. Gross amounts offset in the balance sheet includes cash collateral paid of $115 million at June 30, 2016 and $491 million at December 31, 2015. At June 30, 2016 and December 31, 2015, we did not have any financial instrument collateral received/posted.

[3] At June 30, 2016 and December 31, 2015, we had not received any cash not subject to an enforceable master netting agreement.