Investments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities, Debt	$ 59		$ 59		$ 0
Trading Securities, Equity	60		60		0
Trading Securities	119		119		$ 0
Trading Securities, Realized Gain	1	$ 0	1	$ 0
Trading Securities, Realized Loss	(6)	0	(8)	0
Trading Securities, Realized Gain (Loss)	$ (5)	$ 0	$ (7)	$ 0