Redeemable Noncontrolling Interest - Schedule of Ownership (Details) - AON LLC	6 Months Ended
	Jun. 30, 2024 shares
Equity, Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance (in units)	41,439,847
Issuances (in units)	2,405,906
Repurchases (in units)	(126,728)
Redemptions (in units)	0
Total Units Issued (in units)	43,719,025
Ending balance (in units)	43,719,025
Allocation of income to controlling and noncontrolling interests (in percent)	1
Allocation of losses to controlling and noncontrolling interests (in percent)	1
AON Inc.
Equity, Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance (in units)	13,330,051
Issuances (in units)	2,405,906
Repurchases (in units)	(126,728)
Redemptions (in units)	4,538,228
Total Units Issued (in units)	20,147,457
Ending balance (in units)	20,147,457
Allocation of income to controlling and noncontrolling interests (in percent)	0.374
Allocation of losses to controlling and noncontrolling interests (in percent)	0.259
Legacy AON Shareholders
Equity, Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance (in units)	28,109,796
Issuances (in units)	0
Repurchases (in units)	0
Redemptions (in units)	(4,538,228)
Total Units Issued (in units)	23,571,568
Ending balance (in units)	23,571,568
Allocation of income to controlling and noncontrolling interests (in percent)	0.626
Allocation of losses to controlling and noncontrolling interests (in percent)	0.741