Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Revenue	$ 5,017	$ 4,189	$ 10,100	$ 8,840
Expense:
Compensation and benefits	2,860	2,429	5,667	4,984
Other operating expenses	929	875	1,847	1,901
Operating expenses	3,789	3,304	7,514	6,885
Operating income	1,228	885	2,586	1,955
Other net benefit credits	71	63	142	127
Interest income	1	2	1	4
Interest expense	(110)	(132)	(228)	(259)
Investment income (loss)	19	(31)	30	(33)
Income before income taxes	1,209	787	2,531	1,794
Income tax expense	382	207	706	447
Net income before non-controlling interests	827	580	1,825	1,347
Less: Net income attributable to non-controlling interests	7	8	22	21
Net income attributable to the Company	$ 820	$ 572	$ 1,803	$ 1,326
Net income per share attributable to the Company:
Basic (usd per share)	$ 1.61	$ 1.13	$ 3.55	$ 2.62
Diluted (usd per share)	$ 1.60	$ 1.12	$ 3.51	$ 2.60
Average number of shares outstanding:
Basic (in shares)	508	506	508	505
Diluted (in shares)	513	511	514	510
Shares outstanding (in shares)	507	506	507	506