Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Revenue	$ 4,583	$ 3,968	$ 14,683	$ 12,808
Expense:
Compensation and benefits	2,853	2,495	8,520	7,479
Other operating expenses	990	933	2,837	2,834
Operating expenses	3,843	3,428	11,357	10,313
Operating income	740	540	3,326	2,495
Other net benefit credits	69	60	211	187
Interest income	1	1	2	5
Interest expense	(107)	(128)	(335)	(387)
Investment income (loss)	13	(14)	43	(47)
Income before income taxes	716	459	3,247	2,253
Income tax expense	174	139	880	586
Net income before non-controlling interests	542	320	2,367	1,667
Less: Net income attributable to non-controlling interests	5	4	27	25
Net income attributable to the Company	$ 537	$ 316	$ 2,340	$ 1,642
Net income per share attributable to the Company:
Basic (usd per share)	$ 1.06	$ 0.62	$ 4.61	$ 3.25
Diluted (usd per share)	$ 1.05	$ 0.62	$ 4.56	$ 3.21
Average number of shares outstanding:
Basic (in shares)	506	507	508	506
Diluted (in shares)	513	512	513	511
Shares outstanding (in shares)	505	507	505	507