Segment Information - Reconciliation of Information Reported by Segment to Condensed Consolidated Statement of Comprehensive Income Amounts (Parenthetical) (Details) $ in Billions	12 Months Ended
Dec. 31, 2021 USD ($)
Termination Agreement [Member] \| Termination of Proposed Combination with AON Plc [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Termination payment	$ 1

Gain (loss) related to the termination of a contract between the parties. The termination may be due to many causes including early termination of a lease by a lessee, a breach of contract by one party, or a failure to perform.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3602-108585

Name:	us-gaap_GainLossOnContractTermination
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration