CONSOLIDATED STATEMENT OF INCOME - USD ($) shares in Millions, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Net sales	$ 3,470.9	$ 3,162.4	$ 13,835.9
Cost of sales (including special charges of (a))	2,082.1	1,851.8
Selling, general and administrative expenses	1,008.5	947.2
Special (gains) and charges	26.0	6.2
Operating income	354.3	357.2	1,950.1
Other (income)/expense	(19.4)	(16.8)
Interest expense, net	56.4	62.5
Income before income taxes	317.3	311.5
Provision for income taxes	69.1	54.2
Net income including noncontrolling interest	248.2	257.3	$ 1,518.6	$ 1,246.5
Net income attributable to noncontrolling interest	0.9	3.3
Net income attributable to Ecolab	$ 247.3	$ 254.0
Earnings attributable to Ecolab per common share
Basic (in dollars per share)	$ 0.86	$ 0.87
Diluted (in dollars per share)	0.84	0.86
Dividends declared per common share (in dollars per share)	$ 0.410	$ 0.370
Weighted-average common shares outstanding
Basic (in shares)	288.6	290.6
Diluted (in shares)	292.7	295.0
Product and equipment
Net sales	$ 2,847.2	$ 2,604.4
Cost of sales (including special charges of (a))	1,696.6	1,500.7
Service and lease
Net sales	623.7	558.0
Cost of sales (including special charges of (a))	$ 385.5	$ 351.1