Derivative and Hedging Activities - Components of Interest Income and Interest Expense Table (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Interest expense on senior notes	$ 171	$ 180
Interest expense on term loans	0	29
Amortization of loan discount, issuance costs and other	11	19
Interest expense on credit facilities	3	8
Gains on terminated fair value hedges	(1)	(1)
Gains on undesignated interest rate derivatives	(10)	(18)
Capitalized interest	(123)	(178)
Total interest expense	$ 51	$ 39