UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Millions		Total	Share Capital	Additional Paid in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2020			342,024,612
Beginning balance at Dec. 31, 2020		$ 512.1	$ 0.0	$ 1,791.8	$ (1,331.2)	$ 51.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		31.7			31.7
Exercise of employee stock options (in shares)			76,047
Exercise of employee stock options		0.9		0.9
Employee 401K match with Vertiv stock (in shares)			69,309
Employee 401K match with Vertiv stock		1.3		1.3
Exercise of warrants (in shares)	[1]		9,346,822
Exercise of warrants	[1]	176.0		176.0
Stock-based compensation		5.6		5.6
Other comprehensive income (loss), net of tax		1.1				1.1
Ending balance (in shares) at Mar. 31, 2021			351,516,790
Ending balance at Mar. 31, 2021		728.7	$ 0.0	1,975.6	(1,299.5)	52.6
Beginning balance (in shares) at Dec. 31, 2020			342,024,612
Beginning balance at Dec. 31, 2020		512.1	$ 0.0	1,791.8	(1,331.2)	51.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		97.6
Ending balance (in shares) at Sep. 30, 2021			352,499,706
Ending balance at Sep. 30, 2021		785.7	$ 0.0	1,987.3	(1,233.6)	32.0
Beginning balance (in shares) at Mar. 31, 2021			351,516,790
Beginning balance at Mar. 31, 2021		728.7	$ 0.0	1,975.6	(1,299.5)	52.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		9.7			9.7
Exercise of employee stock options (in shares)			120,721
Exercise of employee stock options		1.4		1.4
Stock comp activity, net of withholdings for tax (in shares)	[2]		586,139
Stock comp activity, net of withholdings for tax	[2]	(0.8)		(0.8)
Employee 401K match with Vertiv stock (in shares)			107,890
Employee 401K match with Vertiv stock		2.3		2.3
Other comprehensive income (loss), net of tax		2.4				2.4
Ending balance (in shares) at Jun. 30, 2021			352,331,540
Ending balance at Jun. 30, 2021		743.7	$ 0.0	1,978.5	(1,289.8)	55.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		56.2			56.2
Exercise of employee stock options (in shares)			51,122
Exercise of employee stock options		0.8		0.8
Stock comp activity, net of withholdings for tax (in shares)	[3]		27,069
Stock comp activity, net of withholdings for tax	[3]	5.5		5.5
Employee 401K match with Vertiv stock (in shares)			89,975
Employee 401K match with Vertiv stock		2.5		2.5
Other comprehensive income (loss), net of tax		(23.0)				(23.0)
Ending balance (in shares) at Sep. 30, 2021			352,499,706
Ending balance at Sep. 30, 2021		$ 785.7	$ 0.0	1,987.3	(1,233.6)	32.0
Beginning balance (in shares) at Dec. 31, 2021		375,801,857	375,801,857
Beginning balance at Dec. 31, 2021		$ 1,417.7	$ 0.0	2,597.5	(1,215.4)	35.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		8.5			8.5
Exercise of employee stock options (in shares)			89,566
Exercise of employee stock options		1.0		1.0
Employee 401K match with Vertiv stock (in shares)			100,541
Employee 401K match with Vertiv stock		2.3		2.3
Stock-based compensation		6.6		6.6
Other comprehensive income (loss), net of tax		18.0				18.0
Ending balance (in shares) at Mar. 31, 2022			375,991,964
Ending balance at Mar. 31, 2022		$ 1,454.1	$ 0.0	2,607.4	(1,206.9)	53.6
Beginning balance (in shares) at Dec. 31, 2021		375,801,857	375,801,857
Beginning balance at Dec. 31, 2021		$ 1,417.7	$ 0.0	2,597.5	(1,215.4)	35.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		$ 50.0
Ending balance (in shares) at Sep. 30, 2022		377,058,727	377,058,727
Ending balance at Sep. 30, 2022		$ 1,267.1	$ 0.0	2,621.9	(1,165.4)	(189.4)
Beginning balance (in shares) at Mar. 31, 2022			375,991,964
Beginning balance at Mar. 31, 2022		1,454.1	$ 0.0	2,607.4	(1,206.9)	53.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		20.3			20.3
Exercise of employee stock options (in shares)			4,279
Exercise of employee stock options		0.1		0.1
Stock comp activity, net of withholdings for tax (in shares)	[4]		563,597
Stock comp activity, net of withholdings for tax	[4]	2.9		2.9
Employee 401K match with Vertiv stock (in shares)			161,333
Employee 401K match with Vertiv stock		2.2		2.2
Other comprehensive income (loss), net of tax		(127.9)				(127.9)
Ending balance (in shares) at Jun. 30, 2022			376,721,173
Ending balance at Jun. 30, 2022		1,351.7	$ 0.0	2,612.6	(1,186.6)	(74.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		21.2			21.2
Exercise of employee stock options (in shares)			20,649
Exercise of employee stock options		0.2		0.2
Employee 401K match with Vertiv stock (in shares)			316,905
Employee 401K match with Vertiv stock		2.8		2.8
Stock-based compensation		6.3		6.3
Other comprehensive income (loss), net of tax		$ (115.1)				(115.1)
Ending balance (in shares) at Sep. 30, 2022		377,058,727	377,058,727
Ending balance at Sep. 30, 2022		$ 1,267.1	$ 0.0	$ 2,621.9	$ (1,165.4)	$ (189.4)

[1] The exercise of warrants includes $107.5 of cash received during the three months ended March 31, 2021 for the exercise of public warrants.

[2] Net stock compensation activity includes 906,197 vested shares offset by 320,058 shares withheld for taxes valued at $7.0 valued and stock-based compensation of $6.2.

[3] Net stock compensation activity includes 29,605 vested shares offset by 2,536 shares withheld for taxes valued at $0.2 and stock-based compensation of $5.7.

[4] Net stock compensation activity includes 876,358 vested shares offset by 312,761 shares withheld for taxes valued at $4.3 and stock-based compensation of $7.2.