EARNINGS (LOSS) PER SHARE - Earnings Per Share Reconciliation (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Basic earnings (loss) per share computation:
Net income (loss)	$ 76.6	$ 119.6	$ (327.3)
Weighted-average number of shares outstanding - basic (in shares)	376,730,519	355,544,632	307,076,397
Basic earnings per share (USD per share)	$ 0.20	$ 0.34	$ (1.07)
Diluted earnings (loss) per share computation:
Net income (loss)	$ 76.6	$ 119.6	$ (327.3)
Gain on fair value of warrant liabilities	(90.9)	0.0	0.0
Net income (loss) adjusted for the gain on fair value of warrant liabilities	$ (14.3)	$ 119.6	$ (327.3)
Weighted-average number of shares outstanding - basic (in shares)	376,730,519	355,544,632	307,076,397
Dilutive effect of private warrants (in shares)	1,493,532	0	0
Dilutive effect of equity-based compensation (in shares)	0	4,595,691	0
Weighted-average number of shares outstanding - diluted (in shares)	378,224,051	360,140,323	307,076,397
Diluted earnings (loss) per share (USD per share)	$ (0.04)	$ 0.33	$ (1.07)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock shares outstanding (in shares)	377,368,837	375,801,857
Gain on fair value of warrant liabilities	$ (90.9)	$ 0.0	$ 0.0
Share Capital
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock shares outstanding (in shares)	377,368,837	375,801,857	342,024,612	118,261,955	[1]
Share Capital | Previously Reported
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock shares outstanding (in shares)			1,000,000.0	1.0

[1] The shares and earnings per share available to holders of the Company’s common shares, prior to the Business Combination, have been recasted as shares reflecting the exchange ratio established in the Business Combination (1.0 Vertiv Holdings share to 118.261955 Vertiv Holdings Co shares).