CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income	$ 1,007.7	$ 275.8	$ 949.6
Foreign currency adjustments:
Foreign currency translation adjustment - Pre Tax	166.2	(22.2)	(110.5)
Foreign currency translation adjustment - Tax	23.1	(5.4)	(14.7)
Foreign currency translation adjustments - Net of Tax	189.3	(27.6)	(125.2)
Foreign currency translation adjustments - reclassification of (gains) losses included in net income - Pre Tax		(36.6)	(0.1)
Foreign currency translation adjustments - reclassification of (gains) losses included in net income - Net of Tax		(36.6)	(0.1)
Cash flow hedges:
Net realized and unrealized gains on cash flow hedges - Pre Tax	9.6	(1.4)	(1.1)
Net realized and unrealized gains on cash flow hedges - Tax	(3.7)	0.5
Net realized and unrealized gains on cash flow hedges - Net of Tax	5.9	(0.9)	(1.1)
Reclassification of (gains) losses included in net income - Pre Tax	(11.5)	6.0
Reclassification of (gains) losses included in net income - Tax	4.8	(2.3)
Reclassification of (gains) losses included in net income - Net of Tax	(6.7)	3.7
Available for sale securities:
Net unrealized gains on available for sale securities - Pre Tax	2.0	2.6	3.3
Net unrealized gains on available for sale securities - Net of Tax	2.0	2.6	3.3
Reclassification of gains included in net income - Pre Tax	(3.5)		(0.9)
Reclassification of gains included in net income - Net of Tax	(3.5)		(0.9)
Pension and Other Retirement Benefits:
Amortization of actuarial losses and prior service costs included in net income - Pre Tax	8.7	9.7	13.5
Amortization of actuarial losses and prior service costs included in net income - Tax	(3.3)	(3.7)	(5.2)
Amortization of actuarial losses and prior service costs included in net income - Net of Tax	5.4	6.0	8.3
Net actuarial gains arising during period	20.9	0.3	18.5
Net actuarial gains and prior service costs - Tax	(8.3)	(0.1)	(7.1)
Net actuarial gains and prior service costs - Net of Tax	12.6	0.2	11.4
Total other comprehensive income (loss) - Pre Tax	192.4	(41.6)	(77.3)
Total other comprehensive income (loss) - Tax	12.6	(11.0)	(27.0)
Total other comprehensive income (loss) - Net of Tax	205.0	(52.6)	(104.3)
Comprehensive income (loss)	1,212.7	223.2	845.3
Less: comprehensive income (loss) attributable to noncontrolling interests and noncontrolling interest	19.4	(18.0)	8.3
Comprehensive income attributable to Moody's	$ 1,193.3	$ 241.2	$ 837.0