Shareholders' Equity (Deficit) - Distributable Profits (Details) - USD ($) $ in Billions	Dec. 31, 2022	Dec. 31, 2021
Equity [Abstract]
Distributable reserves available amount	$ 29.0	$ 32.7

Represents the amount of distributable reserves maintained by the entity.

No definition available.

Name:	aon_DistributableReservesAvailableAmount
Namespace Prefix:	aon_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant