Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Tax Disclosure [Abstract]
Effective tax rate (percent)	23.10%	23.40%	23.20%	12.00%
Excess tax benefits from stock compensation			$ 19
Unrecognized tax benefits, period increase (decrease), net of federal tax	$ 5		$ 11
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 2022 are currently under examination. The Company’s U.K. tax returns for 2017 through 2022 remain open to examination.

Unrecognized Tax Benefits, Period Increase (Decrease), Net of Federal Tax

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- Definition

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

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Amount of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to expense for award under share-based payment arrangement. Excludes expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

+ References

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A brief description of status of the tax examination, significant findings to date, and the entity's position with respect to the findings.

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