CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Net income	$ 221.7	$ 191.1
Foreign currency translation adjustment-Pre Tax Amount	(4.8)	(59.8)
Foreign currency translation adjustment-Tax Amount	0	0
Foreign currency translation adjustments-Net of Tax	(4.8)	(59.8)
Cash Flow And Net Investment Hedges [Abstract]
Net unrealized gain (losses) on cash flow and net investment hedges- Pre Tax	(3.6)	1.4
Net unrealized gain (losses) on cash flow and net investment hedges-Tax Amount	(1.5)	0.6
Net unrealized losses on cash flow and net investment hedges	(2.1)	0.8
Reclassification of losses included in net income-Pre Tax	0	0.6
Reclassification of losses included in net income-Tax Amount	0	0.2
Reclassification of losses included in net income- Net of Tax	0	0.4
Pension and Other Retirement Benefits Net of Tax [Abstract]
Amortization Of Actuarial Losses And Prior Service Costs Included In Net Income Pre Tax	1.7	3.1
Amortization Of Actuarial Losses And Prior Service Costs Included In Net Income Tax	1.5	1.2
Amortization Of Actuarial Losses And Prior Service Costs Included In Net Income Net Of Tax	0.2	1.9
Total other comprehensive income (loss)-Pre Tax	(6.7)	(54.7)
Net current period other comprehensive income/(loss)	0	2.0
Total other comprehensive income (loss)-Net of Tax	(6.7)	(56.7)
Comprehensive income (loss)	215.0	134.4
comprehensive income attributable to noncontrolling interests and redeemable noncontrolling interest	3.7	2.7
Comprehensive income attributable to Moody's	211.3	131.7
Foreign currency translation adjustments - reclassification of losses included in net income due to liquidation of a foreign subsidiary Pre Tax	0	0
Foreign currency translation adjustments - reclassification of losses included in net income due to liquidation of a foreign subsidiary Tax Effect	0	0
Foreign currency translation adjustments - reclassification of losses included in net income due to liquidation of a foreign subsidiary Net of Tax	$ 0	$ 0