Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock, Shares	Common Stock, Amount	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss, Net of Tax	Total IPG Stockholders' Equity	Noncontrolling Interests	Treasury Stock [Member]
Common Stock, shares		390.9
Balance at Dec. 31, 2020	$ 2,943.9		$ 39.0	$ 1,099.3	$ 2,636.9	$ (880.2)	$ 2,895.0	$ 48.9
Net income	360.2
Net income available to IPG common stockholders	355.0				355.0		355.0
Net income attributable to noncontrolling interest	5.2							5.2
Other comprehensive income (loss)	(6.1)					(6.1)	(6.1)
Other comprehensive loss, attributable to noncontrolling interest								0.0
Reclassifications related to redeemable noncontrolling interests	(0.6)							(0.6)
Distributions to noncontrolling interests	(6.8)							6.8
Change in redemption value of redeemable noncontrolling interests	(0.7)				(0.7)		(0.7)
Repurchases of Common Stock	0.0
Common stock dividends	(213.7)				(213.7)		(213.7)
Stock-based compensation, shares		2.9
Stock-based compensation, value	49.4		0.3	49.1			49.4
Exercise of stock options, shares		0.6
Exercise of stock options, value	8.4		0.1	8.3			8.4
Shares withheld for taxes, shares		(0.9)
Shares withheld for taxes, value	(24.4)		0.1	24.3			24.4
Other	(0.5)							(0.5)
Balance at Jun. 30, 2021	3,111.3		39.3	1,132.4	2,777.5	(886.3)	3,062.9	48.4
Common Stock, shares		393.2
Balance at Mar. 31, 2021	2,921.6		39.3	1,107.9	2,623.1	(896.3)	2,874.0	47.6
Net income	267.8
Net income available to IPG common stockholders	263.3				263.3		263.3
Net income attributable to noncontrolling interest	4.5							4.5
Other comprehensive income (loss)	10.1					10.0	10.0
Other comprehensive loss, attributable to noncontrolling interest								0.1
Reclassifications related to redeemable noncontrolling interests	0.4							0.4
Distributions to noncontrolling interests	(3.5)							3.5
Change in redemption value of redeemable noncontrolling interests	(1.7)				(1.7)		(1.7)
Common stock dividends	(107.2)				(107.2)		(107.2)
Stock-based compensation, shares		0.3
Stock-based compensation, value	25.7		0.0	25.7			25.7
Exercise of stock options, shares		0.0
Exercise of stock options, value	0.1		0.0	0.1			0.1
Shares withheld for taxes, shares		0.0
Shares withheld for taxes, value	(1.3)		(0.0)	1.3			1.3
Other	(0.1)							(0.1)
Balance at Jun. 30, 2021	3,111.3		39.3	1,132.4	2,777.5	(886.3)	3,062.9	48.4
Common Stock, shares		393.5
Common Stock, shares		394.3
Balance at Dec. 31, 2021	3,589.2		39.3	1,226.6	3,154.3	(894.2)	3,526.0	63.2	$ 0.0
Net income	392.7
Net income available to IPG common stockholders	389.0				389.0		389.0
Net income attributable to noncontrolling interest	3.7							3.7
Other comprehensive income (loss)	(95.7)					(94.7)	(94.7)
Other comprehensive loss, attributable to noncontrolling interest								(1.0)
Reclassifications related to redeemable noncontrolling interests	2.3			3.1			3.1	(0.8)
Distributions to noncontrolling interests	(5.2)							5.2
Change in redemption value of redeemable noncontrolling interests	(1.3)				(1.3)		(1.3)
Repurchases of Common Stock	(147.9)						(147.9)		(147.9)
Common stock dividends	(230.2)				(230.2)		(230.2)
Stock-based compensation, shares		3.1
Stock-based compensation, value	36.6		0.4	36.2			36.6
Shares withheld for taxes, shares		(1.0)
Shares withheld for taxes, value	(38.2)		0.1	38.1			38.2
Other	(8.7)			(0.5)			(0.5)	9.2
Balance at Jun. 30, 2022	3,489.0		39.6	1,222.1	3,311.8	(988.9)	3,436.7	52.3	(147.9)
Common Stock, shares		396.1
Balance at Mar. 31, 2022	3,548.8		39.7	1,206.0	3,196.7	(892.3)	3,487.0	61.8	(63.1)
Net income	231.8
Net income available to IPG common stockholders	229.6				229.6		229.6
Net income attributable to noncontrolling interest	2.2							2.2
Other comprehensive income (loss)	(97.9)					(96.6)	(96.6)
Other comprehensive loss, attributable to noncontrolling interest								(1.3)
Reclassifications related to redeemable noncontrolling interests	1.0			1.9			1.9	(0.9)
Distributions to noncontrolling interests	(2.1)						(0.0)	2.1
Change in redemption value of redeemable noncontrolling interests	0.1				0.1		0.1
Repurchases of Common Stock	(84.8)						(84.8)		(84.8)
Common stock dividends	(114.6)				(114.6)		(114.6)
Stock-based compensation, shares		0.3
Stock-based compensation, value	18.6		(0.1)	18.7			18.6
Shares withheld for taxes, shares		0.0
Shares withheld for taxes, value	(1.2)		(0.0)	1.2			1.2
Other	(8.7)			(0.5)			(0.5)	9.2
Balance at Jun. 30, 2022	$ 3,489.0		$ 39.6	$ 1,222.1	$ 3,311.8	$ (988.9)	$ 3,436.7	$ 52.3	$ (147.9)
Common Stock, shares		396.4