CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (DEFICIT) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Capital Surplus	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total Moody's Shareholders' Equity (Deficit)	Non-Controlling Interests
Beginning Balance (in shares) at Dec. 31, 2012		342.9			(119.7)
Beginning Balance at Dec. 31, 2012	$ 396.6	$ 3.4	$ 365.1	$ 4,713.3	$ (4,614.5)	$ (82.1)	$ 385.2	$ 11.4
Net income	810.2			804.5			804.5	5.7
Dividends	(221.9)			(215.7)			(215.7)	(6.2)
Stock-based compensation	67.2		67.2				67.2
Shares issued for stock-based compensation plans, net	136.0		(51.9)		$ 187.9		136.0
Shares issued for stock-based compensation plans, net (in shares)					5.0
Net excess tax benefit upon settlement of stock-based compensation awards	33.3		33.3				33.3
Adjustment to redemption value of redeemable noncontrolling interest	(7.9)		(7.9)				(7.9)
Treasury shares repurchased, shares					(14.2)
Treasury shares repurchased	(893.1)				$ (893.1)		(893.1)
Currency translation adjustment	(10.1)					(10.1)	(10.1)
Net actuarial losses and prior service costs - Net of Tax	29.9					29.9	29.9
Amortization of actuarial losses and prior service costs included in net income - Net of Tax	7.0					7.0	7.0
Net unrealized gain on cash flow hedges	0.7					0.7	0.7
Ending Balance at Dec. 31, 2013	347.9	$ 3.4	405.8	5,302.1	$ (5,319.7)	(54.6)	337.0	10.9
Ending Balance (in shares) at Dec. 31, 2013		342.9			(128.9)
Net income	996.6			988.7			988.7	7.9
Dividends	(253.4)			(246.5)			(246.5)	(6.9)
Stock-based compensation	80.6		80.6				80.6
Shares issued for stock-based compensation plans, net	98.0		(58.0)		$ 156.0		98.0
Shares issued for stock-based compensation plans, net (in shares)					4.2
Net excess tax benefit upon settlement of stock-based compensation awards	54.7		54.7				54.7
Adjustment to redemption value of redeemable noncontrolling interest	(99.2)		(99.2)				(99.2)
Treasury shares repurchased, shares					(13.8)
Treasury shares repurchased	(1,220.5)				$ (1,220.5)		(1,220.5)
Currency translation adjustment	(129.3)					(129.3)	(129.3)
Net actuarial losses and prior service costs - Net of Tax	(56.7)					(56.7)	(56.7)
Amortization of actuarial losses and prior service costs included in net income - Net of Tax	4.5					4.5	4.5
Unrealized Gains On Available For Sale Securities	0.9					0.9	0.9
Ending Balance at Dec. 31, 2014	42.9	$ 3.4	383.9	6,044.3	$ (6,384.2)	(235.2)	(187.8)	230.7
Ending Balance (in shares) at Dec. 31, 2014		342.9			(138.5)
ICRA noncontrolling interest	218.8							218.8
Net income	949.6			941.3			941.3	8.3
Dividends	(283.6)			(276.6)			(276.6)	(7.0)
Stock-based compensation	87.5		87.5				87.5
Shares issued for stock-based compensation plans, net	29.6		(63.5)		$ 93.1		29.6
Shares issued for stock-based compensation plans, net (in shares)					2.6
Net excess tax benefit upon settlement of stock-based compensation awards	43.4		43.4				43.4
Treasury shares repurchased, shares					(10.9)
Treasury shares repurchased	(1,098.1)				$ (1,098.1)		(1,098.1)
Currency translation adjustment	(125.3)					(125.3)	(125.3)
Net actuarial losses and prior service costs - Net of Tax	11.4					11.4	11.4
Amortization of actuarial losses and prior service costs included in net income - Net of Tax	8.3					8.3	8.3
Unrealized Gains On Available For Sale Securities	2.4					2.4	2.4
Net unrealized gain on cash flow hedges	(1.1)					(1.1)	(1.1)
Ending Balance at Dec. 31, 2015	$ (333.0)	$ 3.4	$ 451.3	$ 6,709.0	$ (7,389.2)	$ (235.2)	$ (565.0)	$ 230.7
Ending Balance (in shares) at Dec. 31, 2015		342.9			(146.8)