Fair Value of Financial Investments (Details 2) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Income from financial investments, net and impairment charges
Equity investments income (loss), net		$ 2	$ (2)
Total income from financial investments, net	$ 1	7	2
Estimated market value of long-term and short-term debt	3,700	3,700		$ 3,700
Aggregate carrying value of long-term and short-term debt	3,400	3,400		$ 3,400
Private equity funds
Income from financial investments, net and impairment charges
Realized gains from private equity funds	$ 1	$ 5	$ 4