OPERATING SEGMENTS (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018 USD ($) item	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Financial information of reportable segments
Number of reportable segments | item	3
Net sales	$ 3,470.9	$ 3,162.4	$ 13,835.9
Operating Income (Loss)	354.3	357.2	1,950.1
Previously Reported
Financial information of reportable segments
Net sales		3,161.6	13,838.3
Operating Income (Loss)		373.3	2,019.8
Global Industrial
Financial information of reportable segments
Net sales	1,226.0	1,114.2
Global Institutional
Financial information of reportable segments
Net sales	1,206.2	1,074.5
Global Energy
Financial information of reportable segments
Net sales	842.9	757.9
Other
Financial information of reportable segments
Net sales	195.8	215.8
Operating segment
Financial information of reportable segments
Net sales	3,503.9	3,290.4	14,230.0
Operating Income (Loss)	357.5	369.7	2,003.0
Operating segment | Previously Reported
Financial information of reportable segments
Net sales			13,646.2
Operating Income (Loss)			1,986.9
Operating segment | Adjustment | Fixed Currency Rate Change
Financial information of reportable segments
Net sales			586.0
Operating Income (Loss)			85.4
Operating segment | Global Industrial
Financial information of reportable segments
Net sales	1,241.4	1,178.3	5,106.8
Operating Income (Loss)	129.9	135.6	758.5
Operating segment | Global Industrial | Previously Reported
Financial information of reportable segments
Net sales			4,878.5
Operating Income (Loss)			722.0
Operating segment | Global Industrial | Adjustment | Segment Change
Financial information of reportable segments
Net sales			(56.9)
Operating Income (Loss)			2.6
Operating segment | Global Industrial | Adjustment | Fixed Currency Rate Change
Financial information of reportable segments
Net sales			286.0
Operating Income (Loss)			47.5
Operating segment | Global Institutional
Financial information of reportable segments
Net sales	1,218.0	1,114.6	4,910.0
Operating Income (Loss)	198.7	186.8	979.8
Operating segment | Global Institutional | Previously Reported
Financial information of reportable segments
Net sales			4,744.9
Operating Income (Loss)			985.7
Operating segment | Global Institutional | Adjustment | Segment Change
Financial information of reportable segments
Net sales			(23.7)
Operating Income (Loss)			(14.9)
Operating segment | Global Institutional | Adjustment | Fixed Currency Rate Change
Financial information of reportable segments
Net sales			190.2
Operating Income (Loss)			23.5
Operating segment | Global Energy
Financial information of reportable segments
Net sales	847.1	775.7	3,281.7
Operating Income (Loss)	70.9	70.9	336.1
Operating segment | Global Energy | Previously Reported
Financial information of reportable segments
Net sales			3,199.3
Operating Income (Loss)			338.5
Operating segment | Global Energy | Adjustment | Segment Change
Financial information of reportable segments
Net sales			0.7
Operating Income (Loss)			(0.7)
Operating segment | Global Energy | Adjustment | Fixed Currency Rate Change
Financial information of reportable segments
Net sales			81.7
Operating Income (Loss)			15.0
Operating segment | Other
Financial information of reportable segments
Net sales	197.4	221.8	931.5
Operating Income (Loss)	27.1	27.1	142.5
Operating segment | Other | Previously Reported
Financial information of reportable segments
Net sales			823.5
Operating Income (Loss)			149.3
Operating segment | Other | Adjustment | Segment Change
Financial information of reportable segments
Net sales			79.9
Operating Income (Loss)			13.0
Operating segment | Other | Adjustment | Fixed Currency Rate Change
Financial information of reportable segments
Net sales			28.1
Operating Income (Loss)			4.7
Currency Impact
Financial information of reportable segments
Net sales	(33.0)	(128.0)	(394.1)
Operating Income (Loss)	(3.2)	(12.5)	(52.9)
Currency Impact | Previously Reported
Financial information of reportable segments
Net sales			192.1
Operating Income (Loss)			32.9
Currency Impact | Adjustment | Fixed Currency Rate Change
Financial information of reportable segments
Net sales			(586.0)
Operating Income (Loss)			(85.4)
Corporate
Financial information of reportable segments
Operating Income (Loss)	(69.1)	(50.7)	(213.9)
Corporate | Previously Reported
Financial information of reportable segments
Operating Income (Loss)			(208.6)
Corporate | Adjustment | Fixed Currency Rate Change
Financial information of reportable segments
Operating Income (Loss)			(5.3)
Intersegment
Financial information of reportable segments
Net sales	$ 0.0
Revenue Standard Adoption | Adjustment
Financial information of reportable segments
Net sales		0.8	(2.4)
Operating Income (Loss)		0.7	(2.4)
Revenue Standard Adoption | Operating segment | Adjustment
Financial information of reportable segments
Net sales			(2.2)
Operating Income (Loss)			(2.2)
Revenue Standard Adoption | Operating segment | Global Industrial | Adjustment
Financial information of reportable segments
Net sales			(0.8)
Operating Income (Loss)			(0.8)
Revenue Standard Adoption | Operating segment | Global Institutional | Adjustment
Financial information of reportable segments
Net sales			(1.4)
Operating Income (Loss)			(1.4)
Revenue Standard Adoption | Currency Impact | Adjustment
Financial information of reportable segments
Net sales			(0.2)
Operating Income (Loss)			(0.2)
Pension Standard Adoption | Adjustment
Financial information of reportable segments
Operating Income (Loss)		$ (16.8)	(67.3)
Pension Standard Adoption | Operating segment | Adjustment
Financial information of reportable segments
Operating Income (Loss)			(67.1)
Pension Standard Adoption | Operating segment | Global Industrial | Adjustment
Financial information of reportable segments
Operating Income (Loss)			(12.8)
Pension Standard Adoption | Operating segment | Global Institutional | Adjustment
Financial information of reportable segments
Operating Income (Loss)			(13.1)
Pension Standard Adoption | Operating segment | Global Energy | Adjustment
Financial information of reportable segments
Operating Income (Loss)			(16.7)
Pension Standard Adoption | Operating segment | Other | Adjustment
Financial information of reportable segments
Operating Income (Loss)			(24.5)
Pension Standard Adoption | Currency Impact | Adjustment
Financial information of reportable segments
Operating Income (Loss)			$ (0.2)