Condensed Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Net Income	$ 229.8	$ 228.0
Unrealized gain (loss) on cash flow hedge, net of income taxes of ($1.7) for the three months ended March 31, 2015	(2.5)	0
Unrealized gain (loss) on available-for-sale securities, net of income taxes of $0.1 and $0.1 for the three months ended March 31, 2015 and 2014, respectively	0.2	0.1
Foreign currency translation adjustment, net of income taxes of ($175.8) and $15.6 for the three months ended March 31, 2015 and 2014, respectively	(341.3)	30.2
Defined benefit pension and postemployment plans adjustment, net of income taxes of $1.5 and $0.9 for the three months ended March 31, 2015 and 2014, respectively	2.2	1.4
Other Comprehensive Income (Loss)	(341.4)	31.7
Comprehensive Income (Loss)	(111.6)	259.7
Comprehensive Income (Loss) Attributed to Noncontrolling Interests	(2.2)	32.3
Comprehensive Income (Loss) - Omnicom Group Inc.	$ (109.4)	$ 227.4