Insider Trading Arrangements	3 Months Ended	12 Months Ended
	Dec. 31, 2024 shares	Dec. 31, 2024 shares
Trading Arrangements, by Individual
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
John Doyle [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		John Doyle, our Chief Executive Officer, adopted a trading plan on December 2, 2024, which provides for the exercise and sale of an aggregate of 84,318 options. The plan will terminate on December 2, 2025, subject to early termination for certain specified events set forth in the plan.
Name	John Doyle
Title	Chief Executive Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	December 2, 2024
Expiration Date	December 2, 2025
Arrangement Duration	365 days
Aggregate Available	84,318	84,318
Paul Beswick [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		Paul Beswick, our Senior Vice President and Chief Information Officer, adopted a new trading plan on December 6, 2024, which provides for the (1) sale of 2,120 shares, (2) sale up to 7,928 shares subject to performance stock units ("PSUs") and (3) exercise and sale of 5,000 stock options, in each case excluding any shares withheld by the company to satisfy its income tax withholding obligations in connection with the net settlement of equity awards. The plan’s maximum length is until December 5, 2025, subject to early termination for certain specified events set forth in the plan.
Name	Paul Beswick
Title	Senior Vice President and Chief Information Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	December 6, 2024,
Expiration Date	December 5, 2025
Arrangement Duration	364 days
Dean Klisura [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		Dean Klisura, our President and Chief Executive Officer of Guy Carpenter and Vice Chair, Marsh McLennan, adopted a new trading plan on December 6, 2024, which provides for the (1) sale of up to 9,910 shares subject to PSUs, (2) sale of up to 6,024 shares subject to restricted stock units ("RSUs") and (3) exercise and sale of 9,569 stock options, in each case excluding any shares withheld by the company to satisfy its income tax withholding obligations in connection with the net settlement of equity awards. The plan’s maximum length is until December 5, 2025, subject to early termination for certain specified events set forth in the plan.
Name	Dean Klisura
Title	resident and Chief Executive Officer of Guy Carpenter and Vice Chair, Marsh McLennan
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	December 6, 2024,
Expiration Date	December 5, 2025
Arrangement Duration	364 days
Mark McGivney [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		Mark McGivney, our Chief Financial Officer, adopted a new trading plan on December 6, 2024, which provides for the (1) sale of up to 21,472 shares subject to PSUs and (2) exercise and sale of 67,421 stock options, in each case excluding any shares withheld by the company to satisfy its income tax withholding obligations in connection with the net settlement of equity awards. The plan’s maximum length is until December 5, 2025, subject to early termination for certain specified events set forth in the plan.
Name	Mark McGivney
Title	Chief Financial Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	December 6, 2024,
Expiration Date	December 5, 2025
Arrangement Duration	364 days
Stacy Mills [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		Stacy Mills, our Vice President and Controller, adopted a new trading plan on December 6, 2024, which provides for the (1) sale of up to 1,488 shares subject to PSUs, (2) sale of 1,461 shares subject to RSUs and (3) exercise and sale of 4,207 stock options, in each case excluding any shares withheld by the company to satisfy its income tax withholding obligations in connection with the net settlement of equity awards. The plan’s maximum length is until December 5, 2025, subject to early termination for certain specified events set forth in the plan.
Name	Stacy Mills
Title	Vice President and Controller
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	December 6, 2024
Expiration Date	December 5, 2025
Arrangement Duration	364 days
Paul Beswick Rule Trading Arrangement, Shares [Member] | Paul Beswick [Member]
Trading Arrangements, by Individual
Aggregate Available	2,120	2,120
Paul Beswick Trading Arrangement, Shares Subject To Performance Stock Units [Member] | Paul Beswick [Member]
Trading Arrangements, by Individual
Aggregate Available	7,928	7,928
Paul Beswick Rule Trading Arrangement, Stock Options [Member] | Paul Beswick [Member]
Trading Arrangements, by Individual
Aggregate Available	5,000	5,000
Dean Klisura Trading Arrangement, Shares Subject To Performance Stock Units [Member] | Dean Klisura [Member]
Trading Arrangements, by Individual
Aggregate Available	9,910	9,910
Dean Klisura Rule Trading Arrangement, Restricted Stock Units [Member] | Dean Klisura [Member]
Trading Arrangements, by Individual
Aggregate Available	6,024	6,024
Dean Klisura Rule Trading Arrangement, Stock Option [Member] | Dean Klisura [Member]
Trading Arrangements, by Individual
Aggregate Available	9,569	9,569
Mark McGivney Trading Arrangement, Shares Subject To Performance Stock Units [Member] | Mark McGivney [Member]
Trading Arrangements, by Individual
Aggregate Available	21,472	21,472
Mark McGivney Trading Arrangement, Stock Options [Member] | Mark McGivney [Member]
Trading Arrangements, by Individual
Aggregate Available	67,421	67,421
Stacy Mills Trading Arrangement, Shares Subject To Performance Stock Units [Member] | Stacy Mills [Member]
Trading Arrangements, by Individual
Aggregate Available	1,488	1,488
Mark McGivney Trading Arrangement, Shares Subject To Restricted Stock Units [Member] | Stacy Mills [Member]
Trading Arrangements, by Individual
Aggregate Available	1,461	1,461
Stacy Mills Trading Arrangement, Stock Options [Member] | Stacy Mills [Member]
Trading Arrangements, by Individual
Aggregate Available	4,207	4,207