Variable Interest Entities - Revenue and Net Income from Entities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Variable Interest Entity [Line Items]
Total revenue	$ 2,879	$ 2,075
Net income	202	164
Other VIE [Member]
Variable Interest Entity [Line Items]
Total revenue	51	47
Net income	$ 6	$ 7