Accumulated Other Comprehensive Income (Loss) - Schedule of Activity in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 512.1	$ (704.8)	[1]
Ending balance	728.7	276.2
Unrealized losses on cash flow hedges reclassified into earnings	2.7	0.0
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	104.9	32.9
Other comprehensive income (loss), net of tax	(36.1)	(54.3)
Ending balance	68.8	(21.4)
Interest Rate Swap
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(32.8)	0.0
Other comprehensive income (loss), net of tax	33.9	(24.0)
Ending balance	1.1	(24.0)
Pension
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(19.7)	(14.8)
Other comprehensive income (loss), net of tax	(0.8)	(0.2)
Ending balance	(20.5)	(15.0)
Tax Receivable Agreement
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(0.9)	0.0
Other comprehensive income (loss), net of tax	4.1	25.9
Ending balance	3.2	25.9
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	51.5	18.1	[1]
Ending balance	$ 52.6	$ (34.5)

[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).