CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) shares in Millions, $ in Millions	Total	Total IPG Stockholders’ Equity	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated  Other Comprehensive Loss, Net of Tax	Treasury Stock	Non-controlling Interests
Beginning balance (in shares) at Dec. 31, 2023			383.0
Beginning balance at Dec. 31, 2023	$ 4,003.8	$ 3,942.6	$ 38.3	$ 728.5	$ 4,254.5	$ (946.2)	$ (132.5)	$ 61.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	333.2	324.9			324.9			8.3
Other comprehensive income (loss)	(79.3)	(77.8)				(77.8)		(1.5)
Reclassifications related to redeemable non-controlling interests	(3.1)	(2.7)		(2.7)				(0.4)
Distributions to non-controlling interests	(8.6)							(8.6)
Change in redemption value of redeemable non-controlling interests	(3.6)	(3.6)			(3.6)
Repurchase of common stock	(131.1)	(131.1)					(131.1)
Common stock dividends	(250.7)	(250.7)			(250.7)
Stock-based compensation (in shares)			1.1
Stock-based compensation			$ 0.0
Stock-based compensation	47.8	47.8		47.8
Shares withheld for taxes (in shares)			(0.4)
Shares withheld for taxes	(13.5)	(13.5)	$ (0.0)	(13.5)
Other	0.1	(0.3)		(0.3)				0.4
Ending balance (in shares) at Jun. 30, 2024			383.7
Ending balance at Jun. 30, 2024	3,895.0	3,835.6	$ 38.3	759.8	4,325.1	(1,024.0)	(263.6)	59.4
Beginning balance (in shares) at Mar. 31, 2024			383.5
Beginning balance at Mar. 31, 2024	3,883.1	3,824.1	$ 38.3	737.8	4,239.1	(995.7)	(195.4)	59.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	219.6	214.5			214.5			5.1
Other comprehensive income (loss)	(28.6)	(28.3)				(28.3)		(0.3)
Reclassifications related to redeemable non-controlling interests	(3.4)	(2.7)		(2.7)				(0.7)
Distributions to non-controlling interests	(4.3)							(4.3)
Change in redemption value of redeemable non-controlling interests	(3.6)	(3.6)			(3.6)
Repurchase of common stock	(68.2)	(68.2)					(68.2)
Common stock dividends	(124.9)	(124.9)			(124.9)
Stock-based compensation (in shares)			0.2
Stock-based compensation			$ 0.0
Stock-based compensation	25.0	25.0		25.0
Shares withheld for taxes (in shares)			(0.0)
Shares withheld for taxes	(0.2)	(0.2)	$ (0.0)	(0.2)
Other	0.5	(0.1)		(0.1)				0.6
Ending balance (in shares) at Jun. 30, 2024			383.7
Ending balance at Jun. 30, 2024	3,895.0	3,835.6	$ 38.3	759.8	4,325.1	(1,024.0)	(263.6)	59.4
Beginning balance (in shares) at Dec. 31, 2024			372.4
Beginning balance at Dec. 31, 2024	3,864.5	3,797.4	$ 37.2	432.6	4,440.2	(1,112.6)	0.0	67.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	78.3	77.1			77.1			1.2
Other comprehensive income (loss)	224.0	223.1				223.1		0.9
Reclassifications related to redeemable non-controlling interests	2.1							2.1
Distributions to non-controlling interests	(18.4)							(18.4)
Change in redemption value of redeemable non-controlling interests	23.0	23.0			23.0
Repurchase of common stock	(189.8)	(189.8)					(189.8)
Common stock dividends	(246.0)	(246.0)			(246.0)
Stock-based compensation (in shares)			2.0
Stock-based compensation			$ 0.2
Stock-based compensation	43.9	43.9		43.7
Shares withheld for taxes (in shares)			(0.6)
Shares withheld for taxes	(16.0)	(16.0)	$ (0.0)	(16.0)
Other	(0.6)	(0.3)		(0.3)				(0.3)
Ending balance (in shares) at Jun. 30, 2025			373.8
Ending balance at Jun. 30, 2025	3,765.0	3,712.4	$ 37.4	460.0	4,294.3	(889.5)	(189.8)	52.6
Beginning balance (in shares) at Mar. 31, 2025			373.6
Beginning balance at Mar. 31, 2025	3,644.9	3,584.1	$ 37.3	433.8	4,230.7	(1,027.1)	(90.6)	60.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	163.6	162.5			162.5			1.1
Other comprehensive income (loss)	138.3	137.6				137.6		0.7
Reclassifications related to redeemable non-controlling interests	1.5							1.5
Distributions to non-controlling interests	(11.0)							(11.0)
Change in redemption value of redeemable non-controlling interests	23.0	23.0			23.0
Repurchase of common stock	(99.2)	(99.2)					(99.2)
Common stock dividends	(121.9)	(121.9)			(121.9)
Stock-based compensation (in shares)			0.2
Stock-based compensation			$ 0.0
Stock-based compensation	26.5	26.5		26.5
Shares withheld for taxes (in shares)			0.0
Shares withheld for taxes	(0.0)	(0.0)	$ 0.1	(0.1)
Other	(0.7)	(0.2)		(0.2)				(0.5)
Ending balance (in shares) at Jun. 30, 2025			373.8
Ending balance at Jun. 30, 2025	$ 3,765.0	$ 3,712.4	$ 37.4	$ 460.0	$ 4,294.3	$ (889.5)	$ (189.8)	$ 52.6