Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ 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
Quarterly Financial Information Disclosure [Abstract]
Net revenues	$ 2,014	$ 1,568	$ 1,570	$ 1,455	$ 1,353	$ 990	$ 1,044	$ 1,278	$ 6,608	$ 4,664	$ 4,408
Cost of revenues	776	529	598	491	538	337	297	413
Operating income	425	294	232	461	250	196	332	542	1,412	1,319	1,183
Net income	$ 254	$ 199	$ 151	$ 363	$ 159	$ 127	$ 212	$ 394	$ 966	$ 892	$ 835
Basic earnings per common share (in dollars per share)	$ 0.34	$ 0.27	$ 0.20	$ 0.49	$ 0.22	$ 0.17	$ 0.29	$ 0.54	$ 1.30	$ 1.21	$ 1.14
Diluted earnings per common share (in dollars per share)	$ 0.33	$ 0.26	$ 0.20	$ 0.48	$ 0.21	$ 0.17	$ 0.29	$ 0.53	$ 1.28	$ 1.19	$ 1.13