Variable Interest Entities - Revenue and Net Income from Entities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Variable Interest Entity [Line Items]
Total revenue	$ 2,075	$ 1,354
Net income	164	150
Other VIE [Member]
Variable Interest Entity [Line Items]
Total revenue	47	41
Net income	$ 7	$ 11