CONSOLIDATED STATEMENT OF EQUITY - USD ($) $ in Millions	Ecolab Shareholders Equity Cumulative Effect, Period of Adoption, Adjustment	Ecolab Shareholders Equity	Common Stock	Additional Paid-in Capital	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings	OCI (Loss) Cumulative Effect, Period of Adoption, Adjustment	OCI (Loss)	Treasury Stock	Non-Controlling Interest	Cumulative Effect, Period of Adoption, Adjustment	Total
Balance at Dec. 31, 2017	$ (43.6)	$ 7,583.6	$ 354.7	$ 5,435.7	$ (43.6)	$ 8,011.6		$ (1,643.4)	$ (4,575.0)	$ 70.2	$ (43.6)	$ 7,653.8
Balance (in shares) at Dec. 31, 2017			354,715,896						(65,393,098)
Increase (Decrease) in Stockholders' Equity
Net income		1,429.1				1,429.1				11.2		1,440.3
Other comprehensive income (loss) activity		(118.3)						(118.3)		(1.1)		(119.4)
Cash dividends declared		(487.6)				(487.6)				(22.7)		(510.3)
Changes in noncontrolling interest		(7.7)		(7.7)						(7.2)		(14.9)
Stock options and awards		210.0	$ 2.3	205.2					$ 2.5			210.0
Stock options (in shares)			1,833,004						38,679
Stock awards (in shares)			409,200						18,481
Reacquired shares		(562.3)							$ (562.3)			(562.3)
Reacquired shares (in shares)									(3,908,041)
Balance at Dec. 31, 2018	(2.8)	8,003.2	$ 357.0	5,633.2	58.4	8,909.5	$ (61.2)	(1,761.7)	$ (5,134.8)	50.4	(2.8)	8,053.6
Balance (in shares) at Dec. 31, 2018			356,958,100						(69,243,979)
Increase (Decrease) in Stockholders' Equity
Net income		1,558.9				1,558.9				17.3		1,576.2
Other comprehensive income (loss) activity		(266.8)						(266.8)		(1.9)		(268.7)
Cash dividends declared		(533.1)				(533.1)				(25.1)		(558.2)
Changes in noncontrolling interest		0.2		0.2								0.0
Changes in noncontrolling interest										(0.2)
Stock options and awards		279.4	$ 2.6	273.7					$ 3.1			279.4
Stock options (in shares)			2,220,815						41,575
Stock awards (in shares)			390,319						29,173
Reacquired shares		(353.7)							$ (353.7)			(353.7)
Reacquired shares (in shares)									(1,986,241)
Balance at Dec. 31, 2019	$ (4.3)	8,685.3	$ 359.6	5,907.1	$ (4.3)	9,993.7		(2,089.7)	$ (5,485.4)	40.5	$ (4.3)	$ 8,725.8
Balance (in shares) at Dec. 31, 2019			359,569,234						(71,159,472)			288,400,000
Increase (Decrease) in Stockholders' Equity
Retained earnings												$ 9,993.7
Net income		(1,205.1)				(1,205.1)				19.6		(1,185.5)
Other comprehensive income (loss) activity		95.3						95.3		1.8		97.1
Cash dividends declared		(541.3)				(541.3)				(21.0)		(562.3)
Separation of ChampionX		(1,059.9)		(8.5)					$ (1,051.4)	3.4		(1,056.5)
Separation of ChampionX (in shares)									(4,955,552)
Changes in noncontrolling interest		17.6		17.6						(9.3)		8.3
Stock options and awards		325.1	$ 3.0	318.8					$ 3.3			325.1
Stock options (in shares)			2,577,231						35,122
Stock awards (in shares)			406,978						40,122
Reacquired shares		(146.2)							$ (146.2)			(146.2)
Reacquired shares (in shares)									(761,245)
Balance at Dec. 31, 2020		$ 6,166.5	$ 362.6	$ 6,235.0		$ 8,243.0		$ (1,994.4)	$ (6,679.7)	$ 35.0		$ 6,201.5
Balance (in shares) at Dec. 31, 2020			362,553,443						(76,801,025)			285,700,000
Increase (Decrease) in Stockholders' Equity
Retained earnings												$ 8,243.0