Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Valuation allowance	$ 30	$ 30	$ 25	$ 24	$ 21
Unrecognized tax benefits	158	158	211	196	$ 322
Unrecognized tax benefits that would impact effective tax rate	145	$ 145
Income tax examination, description		Moody’s Corporation and subsidiaries are subject to U.S. federal income tax as well as income tax in various state, local and multiple foreign jurisdictions. The Company’s U.S. federal income tax returns for 2022 through 2024 remain open to examination. Currently, the Company's New York State tax returns for 2022 through 2024 are under examination. Additionally, New York City tax returns for the years 2018 through 2022 are also under examination, while returns for 2023 and 2024 are open for examination. Furthermore, the Company's U.K. corporate income tax returns are under audit for the years 2017 through 2023, with the 2024 return still open for examination.
Interest accrued on UTPs	43	$ 43	47	36
Lapse of statute of limitatons	64	$ 70	$ 15	$ 25
Unrecognized tax benefits, reduction resulting from lapse of applicable statute of limitations, related interest	$ 15