Geographic Region (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net revenues	$ 1,370	$ 1,644	$ 1,662	$ 1,134	$ 1,325	$ 1,668	$ 1,651	$ 1,062	$ 5,810	$ 5,706	$ 5,328
Total assets	7,421				7,531				7,421	7,531	7,304
Net property and equipment	267				254				267	254	233
United States [Member]
Segment Reporting Information [Line Items]
Net revenues									5,683	5,579	5,201
Total assets	7,347				7,450				7,347	7,450	7,219
Net property and equipment	265				252				265	252	232
All Other Countries [Member]
Segment Reporting Information [Line Items]
Net revenues									127	127	127
Total assets	74				81				74	81	85
Net property and equipment	$ 2				$ 2				$ 2	$ 2	$ 1