Derivative Financial Instruments - Schedule of Derivative Instruments (Details) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Derivative Asset [Abstract]
Derivatives accounted for as cash flow hedges associated with debt:	[1]	$ 97	$ 104
Non-qualifying hedge activities:	[1]	20	20
Total Derivative Financial Assets	[1]	135	291
Less: Gross amounts offset in the balance sheet	[1],[2]	(135)	(291)
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]	(196)	(207)
Non-qualifying hedge activities:	[1]	(286)	(379)
Total Derivative Financial Liabilities	[1]	(683)	(586)
Less: Gross amounts offset in the balance sheet	[1],[2]	626	504
Net amounts of derivative financial assets and liabilities presented in the balance sheet	[1],[3]	(57)	(82)
Debt [Member]
Derivative Asset [Abstract]
Non-qualifying hedge activities:	[1]	18	167
Derivative Liability [Abstract]
Non-qualifying hedge activities:	[1]	(201)	0
Interest rate swaps [Member]
Derivative Asset [Abstract]
Derivatives accounted for as cash flow hedges associated with debt:	[1]	0	7
Non-qualifying hedge activities:	[1]	20	20
Derivative Liability [Abstract]
Derivatives accounted for as cash flow hedges associated with debt:	[1]	(18)	(74)
Non-qualifying hedge activities:	[1]	(286)	(379)
Interest rate swaps [Member] | Debt [Member]
Derivative Asset [Abstract]
Non-qualifying hedge activities:	[1]	4	117
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]	97	97
Derivative Liability [Abstract]
Derivatives accounted for as cash flow hedges associated with debt:	[1]	(178)	(133)
Currency swaps [Member] | Debt [Member]
Derivative Asset [Abstract]
Non-qualifying hedge activities:	[1]	14	50
Derivative Liability [Abstract]
Non-qualifying hedge activities:	[1]	$ (201)	$ 0

[1] All of our derivatives are bilateral over-the-counter ("OTC") 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 $491 million at December 31, 2015 and $213 million at December 31, 2014. At December 31, 2015 and December 31, 2014, we did not have any financial instrument collateral received/posted.

[3] At December 31, 2015 and December 31, 2014, we had not received any cash not subject to an enforceable master netting agreement.