Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Total net revenues	$ 3,179	$ 3,292	$ 3,196	$ 3,168	$ 3,180	$ 3,014	$ 3,012	$ 2,926	$ 12,835	$ 12,132	$ 11,800
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	652	588	548	696	595	633	511	475
Net income	$ 539	$ 503	$ 462	$ 594	$ 177	$ 507	$ 393	$ 403	$ 2,098	$ 1,480	$ 1,313
Earnings Per Share [Abstract]
Net income (in dollars per basic share)	$ 3.81	$ 3.48	$ 3.14	$ 3.97	$ 1.17	$ 3.31	$ 2.53	$ 2.56	$ 14.41	$ 9.60	$ 7.90
Net income (in dollars per diluted share)	$ 3.76	$ 3.43	$ 3.10	$ 3.91	$ 1.15	$ 3.26	$ 2.50	$ 2.52	$ 14.20	$ 9.44	$ 7.81
Weighted average common shares outstanding
Basic	141.5	144.4	147.0	149.5	151.0	153.0	155.1	157.5	145.6	154.1	166.3
Diluted	143.2	146.5	149.0	152.1	153.8	155.4	157.5	160.1	147.7	156.7	168.2
Cash dividends declared per common share	$ 0.90	$ 0.90	$ 0.90	$ 0.83	$ 0.83	$ 0.83	$ 0.83	$ 0.75