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	878	878			878			0
Dividends	(284)	(283)			(283)			(1)
Stock-based compensation	97	97		97
Shares issued for stock-based compensation plans at average cost, net	(31)	(31)		(27)		$ (4)
Shares issued for stock-based compensation plans at average cost, net (in shares)						700,000
Treasury shares repurchased, inclusive of excise tax	(109)	(109)		0		$ (109)
Treasury shares repurchased, inclusive of excise tax (in shares)						(400,000)
Currency translation adjustment, net of net investment hedge activity (net of tax)	73	74					74	(1)
Net actuarial losses (net of tax)	0
Amortization of actuarial gains and prior service credits	(1)	(1)					(1)
Common stock, shares issued ending balance (in shares) at Jun. 30, 2023			342,900,000
Treasury stock, common, ending balance (shares) at Jun. 30, 2023						(159,400,000)
Ending Balance at Jun. 30, 2023	3,312	3,144	$ 3	1,124	14,213	$ (11,626)	(570)	168
Common stock, shares issued beginning balance (in shares) at Mar. 31, 2023			342,900,000
Treasury stock, common, beginning balance (shares) at Mar. 31, 2023						(159,400,000)
Beginning Balance at Mar. 31, 2023	3,058	2,891	$ 3	1,068	13,979	$ (11,570)	(589)	167
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	377	377			377			0
Dividends	(144)	(143)			(143)			(1)
Stock-based compensation	50	50		50
Shares issued for stock-based compensation plans at average cost, net	17	17		6		$ 11
Shares issued for stock-based compensation plans at average cost, net (in shares)						300,000
Treasury shares repurchased, inclusive of excise tax	(67)	(67)		0		$ (67)
Treasury shares repurchased, inclusive of excise tax (in shares)						(300,000)
Currency translation adjustment, net of net investment hedge activity (net of tax)	23	21					21	2
Net actuarial losses (net of tax)	0
Amortization of actuarial gains and prior service credits	(1)	(1)					(1)
Net realized and unrealized gain on cash flow hedges	(1)	(1)					(1)
Common stock, shares issued ending balance (in shares) at Jun. 30, 2023			342,900,000
Treasury stock, common, ending balance (shares) at Jun. 30, 2023						(159,400,000)
Ending Balance at Jun. 30, 2023	$ 3,312	3,144	$ 3	1,124	14,213	$ (11,626)	(570)	168
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	1,130	1,129			1,129			1
Dividends	(311)	(310)			(310)			(1)
Stock-based compensation	111	111		111
Shares issued for stock-based compensation plans at average cost, net	(37)	(37)		(15)		$ (22)
Shares issued for stock-based compensation plans at average cost, net (in shares)						600,000
Noncontrolling interest resulting from majority acquisition	2	0						2
Treasury shares repurchased, inclusive of excise tax	(383)	(383)		0		$ (383)
Treasury shares repurchased, inclusive of excise tax (in shares)						(1,000,000.0)
Currency translation adjustment, net of net investment hedge activity (net of tax)	(48)	(48)					(48)	0
Net actuarial losses (net of tax)	(2)	(2)					(2)
Amortization of actuarial gains and prior service credits	(1)	(1)					(1)
Net realized and unrealized gain on cash flow hedges	$ 1	1					1
Common stock, shares issued ending balance (in shares) at Jun. 30, 2024			342,900,000
Treasury stock, common, ending balance (shares) at Jun. 30, 2024	(160,818,154)					(160,800,000)
Ending Balance at Jun. 30, 2024	$ 3,938	3,778	$ 3	1,324	15,478	$ (12,410)	(617)	160
Common stock, shares issued beginning balance (in shares) at Mar. 31, 2024			342,900,000
Treasury stock, common, beginning balance (shares) at Mar. 31, 2024						(160,300,000)
Beginning Balance at Mar. 31, 2024	3,735	3,575	$ 3	1,252	15,081	$ (12,153)	(608)	160
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	553	552			552			1
Dividends	(156)	(155)			(155)			(1)
Stock-based compensation	57	57		57
Shares issued for stock-based compensation plans at average cost, net	22	22		15		$ 7
Shares issued for stock-based compensation plans at average cost, net (in shares)						200,000
Treasury shares repurchased, inclusive of excise tax	(264)	(264)				$ (264)
Treasury shares repurchased, inclusive of excise tax (in shares)						(700,000)
Currency translation adjustment, net of net investment hedge activity (net of tax)	(7)	(7)					(7)	0
Net actuarial losses (net of tax)	(1)	(1)					(1)
Amortization of actuarial gains and prior service credits	$ (1)	(1)					(1)
Common stock, shares issued ending balance (in shares) at Jun. 30, 2024			342,900,000
Treasury stock, common, ending balance (shares) at Jun. 30, 2024	(160,818,154)					(160,800,000)
Ending Balance at Jun. 30, 2024	$ 3,938	$ 3,778	$ 3	$ 1,324	$ 15,478	$ (12,410)	$ (617)	$ 160