CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Millions	Total	Total Moody's Shareholders' Equity	Common Stock	Capital Surplus	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss	Non- Controlling Interests
Common stock, shares issued beginning balance (in shares) at Dec. 31, 2022			342,900,000
Treasury stock, common, beginning balance (shares) at Dec. 31, 2022						(159,700,000)
Beginning Balance at Dec. 31, 2022	$ 2,689	$ 2,519	$ 3	$ 1,054	$ 13,618	$ (11,513)	$ (643)	$ 170
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,268	1,267			1,267			1
Dividends	(434)	(425)			(425)			(9)
Stock-based compensation	143	143		143
Shares issued for stock-based compensation plans at average cost, net	(24)	(24)		(22)		$ (2)
Shares issued for stock-based compensation plans at average cost, net (in shares)						700,000
Treasury shares repurchased, inclusive of excise tax	(280)	(280)		0		$ (280)
Treasury shares repurchased, inclusive of excise tax (in shares)						(900,000)
Currency translation adjustment, net of net investment hedge activity (net of tax)	(10)	(9)					(9)	(1)
Net actuarial gains (losses) and prior service costs (net of tax)	1	1					1
Amortization of actuarial gains and prior service credits	(2)	(2)					(2)
Amortization of losses on cash flow hedges	1	1					1
Common stock, shares issued ending balance (in shares) at Sep. 30, 2023			342,900,000
Treasury stock, common, ending balance (shares) at Sep. 30, 2023						(159,900,000)
Ending Balance at Sep. 30, 2023	3,352	3,191	$ 3	1,175	14,460	$ (11,795)	(652)	161
Common stock, shares issued beginning balance (in shares) at Jun. 30, 2023			342,900,000
Treasury stock, common, beginning balance (shares) at Jun. 30, 2023						(159,400,000)
Beginning Balance at Jun. 30, 2023	3,312	3,144	$ 3	1,124	14,213	$ (11,626)	(570)	168
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	390	389			389			1
Dividends	(150)	(142)			(142)			(8)
Stock-based compensation	46	46		46
Shares issued for stock-based compensation plans at average cost, net	7	7		5		$ 2
Shares issued for stock-based compensation plans at average cost, net (in shares)						0
Treasury shares repurchased, inclusive of excise tax	(171)	(171)		0		$ (171)
Treasury shares repurchased, inclusive of excise tax (in shares)						(500,000)
Currency translation adjustment, net of net investment hedge activity (net of tax)	(83)	(83)					(83)	0
Net actuarial gains (losses) and prior service costs (net of tax)	1	1					1
Amortization of actuarial gains and prior service credits	(1)	(1)					(1)
Amortization of losses on cash flow hedges	1	1					1
Common stock, shares issued ending balance (in shares) at Sep. 30, 2023			342,900,000
Treasury stock, common, ending balance (shares) at Sep. 30, 2023						(159,900,000)
Ending Balance at Sep. 30, 2023	$ 3,352	3,191	$ 3	1,175	14,460	$ (11,795)	(652)	161
Common stock, shares issued beginning balance (in shares) at Dec. 31, 2023			342,900,000
Treasury stock, common, beginning balance (shares) at Dec. 31, 2023	(160,430,754)					(160,400,000)
Beginning Balance at Dec. 31, 2023	$ 3,476	3,318	$ 3	1,228	14,659	$ (12,005)	(567)	158
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,664	1,663			1,663			1
Dividends	(473)	(467)			(467)			(6)
Stock-based compensation	169	169		169
Shares issued for stock-based compensation plans at average cost, net	(25)	(25)		(7)		$ (18)
Shares issued for stock-based compensation plans at average cost, net (in shares)						600,000
Noncontrolling interest resulting from majority acquisition	10	0						10
Treasury shares repurchased, inclusive of excise tax	(817)	(817)		0		$ (817)
Treasury shares repurchased, inclusive of excise tax (in shares)						(1,900,000)
Currency translation adjustment, net of net investment hedge activity (net of tax)	65	65					65	0
Net actuarial gains (losses) and prior service costs (net of tax)	(2)	(2)					(2)
Amortization of actuarial gains and prior service credits	(1)	(1)					(1)
Amortization of losses on cash flow hedges	$ 2	2					2
Common stock, shares issued ending balance (in shares) at Sep. 30, 2024			342,900,000
Treasury stock, common, ending balance (shares) at Sep. 30, 2024	(161,671,601)					(161,700,000)
Ending Balance at Sep. 30, 2024	$ 4,068	3,905	$ 3	1,390	15,855	$ (12,840)	(503)	163
Common stock, shares issued beginning balance (in shares) at Jun. 30, 2024			342,900,000
Treasury stock, common, beginning balance (shares) at Jun. 30, 2024						(160,800,000)
Beginning Balance at Jun. 30, 2024	3,938	3,778	$ 3	1,324	15,478	$ (12,410)	(617)	160
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	534	534			534			0
Dividends	(162)	(157)			(157)			(5)
Stock-based compensation	58	58		58
Shares issued for stock-based compensation plans at average cost, net	12	12		8		$ 4
Shares issued for stock-based compensation plans at average cost, net (in shares)						0
Noncontrolling interest resulting from majority acquisition	8	0						8
Treasury shares repurchased, inclusive of excise tax	(434)	(434)				$ (434)
Treasury shares repurchased, inclusive of excise tax (in shares)						(900,000)
Currency translation adjustment, net of net investment hedge activity (net of tax)	113	113					113	0
Net actuarial gains (losses) and prior service costs (net of tax)	0
Amortization of actuarial gains and prior service credits	0
Amortization of losses on cash flow hedges	$ 1	1					1
Common stock, shares issued ending balance (in shares) at Sep. 30, 2024			342,900,000
Treasury stock, common, ending balance (shares) at Sep. 30, 2024	(161,671,601)					(161,700,000)
Ending Balance at Sep. 30, 2024	$ 4,068	$ 3,905	$ 3	$ 1,390	$ 15,855	$ (12,840)	$ (503)	$ 163