Earnings (Loss) Per Share - Earnings Per Share Reconciliation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019		Dec. 31, 2019		Dec. 31, 2018
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss	$ (268.9)	$ (74.3)
Basic (in shares)	240,656,864	118,261,955
Lees dilutive effect of equity-based compensation and warrants (in shares)	0	0
Diluted (in shares)	240,656,864	118,261,955
Net income per share attributable to common shareholders
Basic (USD per share)	$ (1.12)	$ (0.63)
Diluted (USD per share)	$ (1.12)	$ (0.63)
Common stock, shares outstanding (in shares)	328,411,705			118,261,955
Share Capital
Net income per share attributable to common shareholders
Common stock, shares outstanding (in shares)	328,411,705	118,261,955	[1]	118,261,955	[1]	118,261,955	[1]
Previously Reported | Share Capital
Net income per share attributable to common shareholders
Common stock, shares outstanding (in shares)				1,000,000		1,000,000.0

[1] The shares and earnings per share available to holders of the Company’s ordinary 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).