Derivative and Hedging Activities - Components of Interest Income and Interest Expense Table (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Interest expense on senior notes	$ 171	$ 184	$ 342	$ 364
Interest expense on term loan	0	7	0	36
Amortization of loan discount, issuance costs and other	12	16	23	35
Interest expense on credit facilities	3	9	6	17
Gains on terminated fair value hedges	(1)	(1)	(2)	(2)
Gains on undesignated interest rate derivatives	0	(33)	(10)	(51)
Capitalized interest	(114)	(155)	(237)	(333)
Total interest expense	$ 71	$ 27	$ 122	$ 66