Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Revenue	$ 5,083	$ 4,651
Expense:
Compensation and benefits	2,807	2,555
Other operating expenses	918	1,026
Operating expenses	3,725	3,581
Operating income	1,358	1,070
Other net benefit credits	71	64
Interest income	0	2
Interest expense	(118)	(127)
Investment income (loss)	11	(2)
Income before income taxes	1,322	1,007
Income tax expense	324	240
Net income before non-controlling interests	998	767
Less: Net income attributable to non-controlling interests	15	13
Net income attributable to the Company	$ 983	$ 754
Net income per share attributable to the Company:
Basic (usd per share)	$ 1.93	$ 1.49
Diluted (usd per share)	$ 1.91	$ 1.48
Average number of shares outstanding:
Basic (in shares)	509	505
Diluted (in shares)	514	510
Shares outstanding (in shares)	509	506