Derivative and Hedging Activities - Components of Interest Income and Interest Expense Table (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Interest expense on senior notes	$ 115	$ 171
Amortization of loan discount, issuance costs and other	10	11
Interest expense on credit facilities	5	3
Gains on terminated fair value hedges	0	(1)
(Gains) losses on undesignated interest rate derivatives	0	(10)
Capitalized interest	(68)	(123)
Total interest expense	$ 62	$ 51