CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Revenue	$ 1,435	$ 1,214	$ 2,725	$ 2,356
Expenses
Operating	362	340	702	682
Selling, general and administrative	307	275	608	556
Restructuring	(2)	53	(3)	59
Depreciation and amortization	58	52	107	102
Acquisition-Related Expenses	0	2	0	3
Loss pursuant to the divestiture of MAKS	0	9	9	9
Total expenses	725	731	1,423	1,411
Operating income	710	483	1,302	945
Non-operating (expense) income, net
Interest expense, net	(60)	(51)	(100)	(103)
Other non-operating income, net	16	0	28	2
Total non-operating expense, net	(44)	(51)	(72)	(101)
Income before provisions for income taxes	666	432	1,230	844
Provision for income taxes	157	121	234	159
Net income	509	311	996	685
Less: Net (loss) income attributable to noncontrolling interests	0	1	(1)	2
Net income attributable to Moody's	$ 509	$ 310	$ 997	$ 683
Earnings per share attributable to Moody's common shareholders
Basic (in usd per share)	$ 2.71	$ 1.64	$ 5.31	$ 3.60
Diluted (in usd per share)	$ 2.69	$ 1.62	$ 5.27	$ 3.56
Weighted average number of shares outstanding
Basic (in shares)	187.7	189.4	187.6	189.9
Diluted (in shares)	189.0	191.3	189.3	192.1