Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Income	$ 1,246.7	$ 1,203.4	$ 1,233.1
Cash flow hedge:
Loss for the period	(48.9)	(5.6)	0.0
Amortization of loss included in interest expense	4.0	0.0	0.0
Income tax effect	18.7	2.3	0.0
Other comprehensive income (loss)	(26.2)	(3.3)	0.0
Defined benefit pension plans and postemployment arrangements:
Unrecognized actuarial losses and prior service cost for the period	(18.3)	(7.8)	(48.4)
Amortization of prior service cost included in periodic benefit expense	7.6	7.5	6.4
Amortization of actuarial losses included in periodic benefit expense	6.4	7.3	3.2
Income tax effect	1.6	(2.8)	15.5
Other comprehensive income (loss)	(2.7)	4.2	(23.3)
Available-for-sale securities:
Unrealized gain for the period	0.2	0.4	0.6
Income tax effect	(0.1)	(0.1)	(0.2)
Other comprehensive income (loss)	0.1	0.3	0.4
Foreign currency translation adjustment	(319.4)	(427.2)	(442.4)
Other Comprehensive Income (Loss)	(348.2)	(426.0)	(465.3)
Comprehensive Income	898.5	777.4	767.8
Comprehensive Income Attributed To Noncontrolling Interests	90.5	80.7	90.4
Comprehensive Income - Omnicom Group Inc.	$ 808.0	$ 696.7	$ 677.4