CONSOLIDATED STATEMENT OF EQUITY - USD ($) $ in Millions	Ecolab Shareholders Equity	Common Stock	Additional Paid-in Capital	Retained Earnings	OCI (Loss)	Treasury Stock	Non-Controlling Interest	Total
Balance at Dec. 31, 2015	$ 6,909.9	$ 350.3	$ 5,086.1	$ 6,160.3	$ (1,423.3)	$ (3,263.5)	$ 70.5	$ 6,980.4
Increase (Decrease) in Stockholders' Equity
New accounting guidance adoption	(29.3)			(29.3)				(29.3)
Net income	1,229.0			1,229.0			17.5	1,246.5
Comprehensive income (loss) activity	(289.6)				(289.6)		(1.3)	(290.9)
Cash dividends declared	(414.9)			(414.9)			(16.9)	(431.8)
Stock options and awards	205.7	2.3	200.2			3.2		205.7
Reacquired shares	(739.6)		(15.5)			(724.1)		(739.6)
Balance at Dec. 31, 2016	6,871.2	352.6	5,270.8	6,945.1	(1,712.9)	(3,984.4)	69.8	6,941.0
Increase (Decrease) in Stockholders' Equity
New accounting guidance adoption	1.9			1.9				1.9
Net income	1,504.6			1,504.6			14.0	1,518.6
Comprehensive income (loss) activity	69.5				69.5		1.7	71.2
Cash dividends declared	(440.0)			(440.0)			(19.3)	(459.3)
Acquisition of noncontrolling interests							4.0	4.0
Stock options and awards	176.7	2.1	170.3			4.3		176.7
Reacquired shares	(600.3)		(5.4)			(594.9)		(600.3)
Balance at Dec. 31, 2017	7,583.6	354.7	5,435.7	8,011.6	(1,643.4)	(4,575.0)	70.2	7,653.8
Increase (Decrease) in Stockholders' Equity
New accounting guidance adoption	(43.6)			(43.6)				(43.6)
Net income	1,034.0			1,034.0			6.1	1,040.1
Comprehensive income (loss) activity	(122.0)				(122.0)		(0.2)	(122.2)
Cash dividends declared	(355.1)			(355.1)			(15.4)	(370.5)
Acquisition of noncontrolling interests	(7.7)		(7.7)				(7.1)	(14.8)
Stock options and awards	161.6	1.8	158.0			1.8		161.6
Reacquired shares	(321.4)					(321.4)		(321.4)
Balance at Sep. 30, 2018	$ 7,929.4	$ 356.5	$ 5,586.0	$ 8,646.9	$ (1,765.4)	$ (4,894.6)	$ 53.6	$ 7,983.0