Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended										12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020		Jun. 30, 2020		Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Total net revenues	$ 3,183	$ 3,003		$ 2,712		$ 3,001	$ 3,287	$ 3,317	$ 3,245	$ 3,118	$ 11,899	$ 12,967	$ 12,835
Pretax income	190	(184)		(526)		2,351	534	641	587	470	1,831	2,232	2,484
Net income	$ 177	$ (140)		$ (539)		$ 2,036	$ 463	$ 543	$ 492	$ 395	$ 1,534	$ 1,893	$ 2,098
Earnings per share
Net income (in dollars per basic share)	$ 1.46	$ (1.14)		$ (4.31)		$ 16.11	$ 3.59	$ 4.09	$ 3.61	$ 2.85	$ 12.39	$ 14.12	$ 14.41
Net income (in dollars per diluted share)	$ 1.43	$ (1.14)	[1]	$ (4.31)	[1]	$ 15.88	$ 3.53	$ 4.04	$ 3.57	$ 2.82	$ 12.20	$ 13.92	$ 14.20
Weighted average common shares outstanding
Basic	120.9	123.0		125.0		126.4	129.0	132.7	136.1	138.8	123.8	134.1	145.6
Diluted	123.4	124.9		126.2		128.2	131.3	134.5	138.0	140.1	125.7	136.0	147.7
Cash dividends declared per common share	$ 1.04	$ 1.04		$ 1.04		$ 0.97	$ 0.97	$ 0.97	$ 0.97	$ 0.90

[1] Diluted shares used in this calculation represent basic shares due to the net loss. Using actual diluted shares would result in anti-dilution.