Segment Information - Reconciliation of Information Reported by Segment to Condensed Consolidated Statement of Comprehensive Income Amounts (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenue:
Revenue		$ 1,953		$ 1,973	$ 6,144	$ 6,292
Income/(loss) from operations		154		1,131	470	1,512
Impairment			$ (81)		(81)	0
Amortization		(71)		(85)	(239)	(285)
Restructuring costs		(9)		0	(71)	0
Interest expense		(54)		(50)	(154)	(161)
Other income, net		85		105	205	617
Income from continuing operations before income taxes		185		1,186	521	1,968
Divested Businesses [Member]
Revenue:
Revenue	[1]	0		8	0	68
Operating Segments [Member]
Revenue:
Revenue		1,927		1,955	6,073	6,176
Income/(loss) from operations		341		379	1,175	1,246
Segment Reconciling Items [Member]
Revenue:
Revenue		26		10	71	48
Income/(loss) from operations		154		1,131	470	1,512
Divested businesses	[1]	0		(20)	0	(49)
Impairment	[2]	0		0	(81)	0
Amortization		(71)		(85)	(239)	(285)
Restructuring costs		(9)		0	(71)	0
Transaction and transformation, net	[3]	(50)		952	(108)	877
Unallocated, net	[4]	(57)		(95)	(206)	(277)
Interest expense		(54)		(50)	(154)	(161)
Other income, net		$ 85		$ 105	$ 205	$ 617

[1] Represents the revenue and income from operations of certain Investment, Risk and Reinsurance businesses which were divested in 2021 and not classified as discontinued operations.

[2] Represents the impairment related to the net assets of our Russian business that are held outside of our Russian entities (see Note 3 — Acquisitions and Divestitures for further information).

[3] In 2022, in addition to legal fees and other transaction costs, includes primarily consulting fees related to the Transformation program (see Note 6 — Restructuring Costs). In 2021, includes the $1 billion income receipt related to the termination of, and fees related to, our then-proposed Aon combination.

[4] Includes certain costs, primarily related to corporate functions which are not directly related to the segments, and certain differences between budgeted expenses determined at the beginning of the year and actual expenses that we report for U.S. GAAP purposes.