Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Effective tax rate (percent)	23.30%	1.00%
Unrecognized tax benefits, increase resulting from current period tax positions	$ 3
Excess tax benefits from stock compensation	14
Overall increase (decrease) in unrecognized tax benefits (UTPs)	6
Unrecognized tax benefits, period increase (decrease), net of federal tax	$ 5
Income tax examination, description	Moody’s is subject to U.S. federal income tax as well as income tax in various state, local and foreign jurisdictions. The Company’s U.S. federal income tax returns for 2019 through 2020 are currently under examination and 2021 through 2022 remain open to examination. The Company’s New York City tax returns for 2018 through 2020 are currently under examination. The Company’s U.K. tax returns for 2017 through 2022 remain open to examination.
Inflation reduction act impact on ETR	In August 2022, the U.S. Congress passed the Inflation Reduction Act, which included a corporate minimum tax on book earnings of 15%, an excise tax on corporate share repurchases of 1%, and certain climate change and energy tax credit incentives. The adoption of a corporate minimum tax of 15% is not expected to impact Moody’s ETR. The excise tax of 1% on corporate share buybacks will not have an impact on the Company’s ETR for 2024.