v3.24.1.u1
Cover - shares
 3 Months Ended
Mar. 31, 2024
Apr. 25, 2024
Entity Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2024  
Document Transition Report false  
Entity File Number 1-7933  
Entity Registrant Name Aon plc  
Entity Incorporation, State or Country Code L2  
Entity Tax Identification Number 98-1539969  
Entity Address, Address Line One Metropolitan Building, James Joyce Street  
Entity Address, City or Town Dublin 1  
Entity Address, Country IE  
Entity Address, Postal Zip Code D01 K0Y8  
Country Region 353  
City Area Code 1  
Local Phone Number 266 6000  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   217,430,759
Entity Central Index Key 0000315293  
Amendment Flag false  
Document Fiscal Year Focus 2024  
Document Fiscal Period Focus Q1  
Current Fiscal Year End Date --12-31  
Class A Ordinary Shares $0.01 nominal value    
Entity Information [Line Items]    
Title of 12(b) Security Class A Ordinary Shares $0.01 nominal value  
Trading Symbol AON  
Security Exchange Name NYSE  
Guarantees of Aon plc’s 3.50% Senior Notes due 2024    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon plc’s 3.50% Senior Notes due 2024  
Trading Symbol AON24  
Security Exchange Name NYSE  
Guarantees of Aon plc’s 3.875% Senior Notes due 2025    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon plc’s 3.875% Senior Notes due 2025  
Trading Symbol AON25  
Security Exchange Name NYSE  
Guarantees of Aon plc’s 2.875% Senior Notes due 2026    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon plc’s 2.875% Senior Notes due 2026  
Trading Symbol AON26  
Security Exchange Name NYSE  
Guarantees of Aon Corporation and Aon Global Holdings plc’s 2.85% Senior Notes due 2027    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon Corporation and Aon Global Holdings plc’s 2.85% Senior Notes due 2027  
Trading Symbol AON27  
Security Exchange Name NYSE  
Guarantees of Aon North America, Inc.’s 5.125% Senior Notes due 2027    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon North America, Inc.’s 5.125% Senior Notes due 2027  
Trading Symbol AON27B  
Security Exchange Name NYSE  
Guarantees of Aon North America, Inc.’s 5.150% Senior Notes due 2029    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon North America, Inc.’s 5.150% Senior Notes due 2029  
Trading Symbol AON29  
Security Exchange Name NYSE  
Guarantees of Aon Corporation and Aon Global Holdings plc’s 2.05% Senior Notes due 2031    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon Corporation and Aon Global Holdings plc’s 2.05% Senior Notes due 2031  
Trading Symbol AON31  
Security Exchange Name NYSE  
Guarantees of Aon Corporation and Aon Global Holdings plc’s 2.60% Senior Notes due 2031    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon Corporation and Aon Global Holdings plc’s 2.60% Senior Notes due 2031  
Trading Symbol AON31A  
Security Exchange Name NYSE  
Guarantees of Aon North America, Inc.’s 5.300% Senior Notes due 2031    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon North America, Inc.’s 5.300% Senior Notes due 2031  
Trading Symbol AON31B  
Security Exchange Name NYSE  
Guarantees of Aon Corporation and Aon Global Holdings plc’s 5.00% Senior Notes due 2032    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon Corporation and Aon Global Holdings plc’s 5.00% Senior Notes due 2032  
Trading Symbol AON32  
Security Exchange Name NYSE  
Guarantees of Aon Corporation and Aon Global Holdings plc’s 5.35% Senior Notes due 2033    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon Corporation and Aon Global Holdings plc’s 5.35% Senior Notes due 2033  
Trading Symbol AON33  
Security Exchange Name NYSE  
Guarantees of Aon North America, Inc.’s 5.450% Senior Notes due 2034    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon North America, Inc.’s 5.450% Senior Notes due 2034  
Trading Symbol AON34  
Security Exchange Name NYSE  
Guarantees of Aon plc’s 4.25% Senior Notes due 2042    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon plc’s 4.25% Senior Notes due 2042  
Trading Symbol AON42  
Security Exchange Name NYSE  
Guarantees of Aon plc’s 4.45% Senior Notes due 2043    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon plc’s 4.45% Senior Notes due 2043  
Trading Symbol AON43  
Security Exchange Name NYSE  
Guarantees of Aon plc’s 4.60% Senior Notes due 2044    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon plc’s 4.60% Senior Notes due 2044  
Trading Symbol AON44  
Security Exchange Name NYSE  
Guarantees of Aon plc’s 4.75% Senior Notes due 2045    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon plc’s 4.75% Senior Notes due 2045  
Trading Symbol AON45  
Security Exchange Name NYSE  
Guarantees of Aon Corporation and Aon Global Holdings plc’s 2.90% Senior Notes due 2051    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon Corporation and Aon Global Holdings plc’s 2.90% Senior Notes due 2051  
Trading Symbol AON51  
Security Exchange Name NYSE  
Guarantees of Aon Corporation and Aon Global Holdings plc’s 3.90% Senior Notes due 2052    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon Corporation and Aon Global Holdings plc’s 3.90% Senior Notes due 2052  
Trading Symbol AON52  
Security Exchange Name NYSE  
Guarantees of Aon North America, Inc.’s 5.750% Senior Notes due 2054    
Entity Information [Line Items]    
Title of 12(b) Security Guarantees of Aon North America, Inc.’s 5.750% Senior Notes due 2054  
Trading Symbol AON54  
Security Exchange Name NYSE