CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net Income	$ 390	$ 303	$ 1,268	$ 1,128
Other Comprehensive Income (Loss):
Foreign currency translation adjustments - Pre Tax	(174)	(358)	(14)	(806)
Foreign currency translation adjustments - Tax	(2)	6	(4)	10
Foreign currency translation adjustments - Net of Tax	(176)	(352)	(18)	(796)
Foreign currency translation adjustments - reclassification of losses included in net income - Pre tax			0	20
Foreign currency translation adjustments - reclassification of losses included in net income, Tax			0	0
Foreign currency translation adjustments - reclassification of losses included in net income, Net of Tax			0	(20)
Net gains on net investment hedges - Pre Tax	124	256	11	561
Net gains on net investment hedges - Tax	(31)	(63)	(3)	(140)
Net gains on net investment hedges - Net of Tax	93	193	8	421
Cash Flow Hedges:
Reclassification of losses included in net income - Pre Tax	1	1	2	2
Reclassification of losses included in net income - Tax	0	(1)	(1)	(1)
Reclassification of losses included in net income - Net of Tax	1	0	1	1
Pension and Other Retirement Benefits:
Amortization of actuarial gains/prior service credits and settlement charge included in net income - Pre Tax	(1)	1	(3)	2
Amortization of actuarial gains/prior service credits and settlement charge included in net income - Tax	0	0	1	0
Amortization of actuarial gains/prior service credits and settlement charge included in net income - Net of tax	(1)	1	(2)	2
Net actuarial and prior service costs - Pre Tax	2	0	2	3
Net actuarial and prior service costs - Tax	(1)	0	(1)	(1)
Net actuarial and prior service costs - Net of Tax	1	0	1	2
Total other comprehensive loss - Pre Tax	(48)	(100)	(2)	(218)
Total other comprehensive loss - Tax	(34)	(58)	(8)	(132)
Total other comprehensive loss - Net of Tax	(82)	(158)	(10)	(350)
Comprehensive income	308	145	1,258	778
Less: comprehensive income (loss) attributable to noncontrolling interests	0	(9)	(1)	(12)
Comprehensive Income Attributable to Moody's	$ 308	$ 154	$ 1,259	$ 790