CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 2,214	$ 1,777	$ 1,429
Foreign Currency Adjustments:
Foreign currency translation adjustment - Pre Tax	(303)	361	(22)
Foreign currency translation adjustment - Tax	11	(13)	(1)
Foreign currency translation adjustment - Net of Tax	(292)	348	(23)
Foreign currency translation adjustments - reclassification of losses included in net income - Pre Tax	0	0	32
Foreign currency translation adjustments - reclassification of losses included in net income - Tax	0	0	0
Foreign currency translation adjustments - reclassification of losses included in net income - Net of Tax	0	0	32
Net (losses) gains on net investment hedges - Pre Tax	319	(364)	35
Net (losses) gains on net investment hedges - Tax	(77)	91	(9)
Net (losses) gains on net investment hedges - Net of Tax	242	(273)	26
Net investment hedges - reclassification of gains included in net income - Pre Tax	(2)	(1)	(3)
Net investment hedges - reclassification of gains included in net income - Tax	1	0	1
Net investment hedges - reclassification of gains included in net income - Net of Tax	(1)	(1)	(2)
Cash Flow Hedges:
Net losses on cash flow hedges - Pre Tax	0	(68)	0
Net losses on cash flow hedges - Tax	0	17	0
Net losses on cash flow hedges - Net of Tax	0	(51)	0
Reclassification of (losses) gains included in net income - Pre Tax	2	3	0
Reclassification of (losses) gains included in net income - Tax	0	(1)	0
Reclassification of (losses) gains included in net income - Net of Tax	2	2	0
Pension and Other Retirement Benefits:
Amortization of actuarial losses and prior service costs and settlement charge included in net income, before tax	19	8	3
Amortization of actuarial losses and prior service costs and settlement charge included in net income - Tax	(5)	(2)	(1)
Amortization of actuarial losses and prior service costs and settlement charge included in net income - Net of Tax	14	6	2
Net actuarial (losses) gains and prior service costs - Pre Tax	73	(42)	(32)
Net actuarial (losses) gains and prior service costs - Tax	(18)	10	8
Net actuarial (losses) gains and prior service costs - Net of Tax	55	(32)	(24)
Total other comprehensive (loss) income - Pre Tax	108	(103)	13
Total other comprehensive (loss)income - Tax	(88)	102	(2)
Total Other Comprehensive Income (Loss)	20	(1)	11
Comprehensive Income	2,234	1,776	1,440
Less: comprehensive (loss) income attributable to noncontrolling interests	(2)	(8)	11
Comprehensive Income Attributable to Moody’s	$ 2,236	$ 1,784	$ 1,429