RETIREMENT PLANS - Assumption Details (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S. Pension
Weighted-average actuarial assumptions used to determine benefit obligations as of year end:
Discount rate (as a percent)	4.27%		4.27%	4.51%	4.14%
Projected salary increase (as a percent)	4.03%		4.03%	4.32%	4.32%
Weighted-average actuarial assumptions used to determine net cost:
Discount rate (as a percent)			4.51%	4.14%	4.92%
Expected return on plan assets (as a percent)			7.75%	7.75%	7.75%
Projected salary increase (as a percent)			4.32%	4.32%	4.32%
Defined Benefit Plan Assumed Health Care Cost Trend Rates
Plan amendments			$ 1.2
U.S. Pension | Corporate bonds | Minimum
Weighted-average actuarial assumptions used to determine net cost:
Maturity period of debt securities			6 months
U.S. Pension | Corporate bonds | Maximum
Weighted-average actuarial assumptions used to determine net cost:
Maturity period of debt securities			30 years
International Pension
Weighted-average actuarial assumptions used to determine benefit obligations as of year end:
Discount rate (as a percent)	2.33%		2.33%	2.93%	3.02%
Projected salary increase (as a percent)	2.52%		2.52%	2.50%	2.66%
Weighted-average actuarial assumptions used to determine net cost:
Discount rate (as a percent)			2.68%	2.78%	4.45%
Expected return on plan assets (as a percent)			6.71%	6.80%	6.90%
Projected salary increase (as a percent)			2.75%	2.83%	3.58%
Defined Benefit Plan Assumed Health Care Cost Trend Rates
Plan amendments			$ 2.0	$ (5.3)
U.S. Postretirement Health Care
Weighted-average actuarial assumptions used to determine benefit obligations as of year end:
Discount rate (as a percent)	4.14%	3.29%	4.14%	4.38%	4.08%
Projected salary increase (as a percent)	0.00%		0.00%
Weighted-average actuarial assumptions used to determine net cost:
Discount rate (as a percent)			4.38%	4.08%	4.77%
Expected return on plan assets (as a percent)			7.75%	7.75%	7.75%
Projected salary increase (as a percent)			0.00%
Defined Benefit Plan Assumed Health Care Cost Trend Rates
Annual rates of increase in the per capita cost of covered health care for pre-age 65 retirees (as a percent)			6.75%
Annual rates of increase in the per capita cost of covered health care for post-age 65 retirees (as a percent)			7.25%
Rate of per capita cost of covered health care in 2023 (as a percent)				5.00%
Plan amendments			$ (62.2)
Defined Benefit Plan, Reduction in Benefit Cost	$ 5.0
Effect of a one-percentage point change in the assumed health care cost trend rate:
Effect on total of service and interest cost components, increase			0.0
Effect on total of service and interest cost components, decrease			0.0
Effect on postretirement benefit obligation, increase			0.7
Effect on total of service and interest cost components, increase			$ (0.7)
U.S. Postretirement Health Care | Nalco
Weighted-average actuarial assumptions used to determine benefit obligations as of year end:
Discount rate (as a percent)		3.60%
Ecolab and Nalco Combined Plans
Defined Benefit Plan Assumed Health Care Cost Trend Rates
Plan amendments		$ (50.0)
Plan amendments, after tax		$ 31.0