CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Revenue	$ 1,600	$ 1,290
Expenses
Operating	393	340
Selling, general and administrative	293	301
Depreciation and amortization	59	49
Restructuring	2	(1)
Loss pursuant to the divestiture of MAKS	0	9
Total expenses	747	698
Operating income	853	592
Non-operating (expense) income, net
Interest expense, net	(7)	(40)
Other non-operating income, net	16	12
Total non-operating (expense) income, net	9	(28)
Income before provisions for income taxes	862	564
Provision for income taxes	126	77
Net income	736	487
Less: Net income (loss) attributable to noncontrolling interests	0	(1)
Net income attributable to Moody's	$ 736	$ 488
Earnings per share attributable to Moody's common shareholders
Basic (in usd per share)	$ 3.93	$ 2.60
Diluted (in usd per share)	$ 3.90	$ 2.57
Weighted average number of shares outstanding
Basic (in shares)	187.2	187.5
Diluted (in shares)	188.6	189.6