UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS’ EQUITY (DEFICIT) - USD ($) $ in Millions		Total	Common Share Capital	Treasury Share Capital	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2023			381,788,876
Beginning balance at Dec. 31, 2023		$ 2,014.9	$ 0.0	$ 0.0	$ 2,711.3	$ (691.9)	$ (4.5)
Beginning balance, treasury (in shares) at Dec. 31, 2023				0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		(5.9)				(5.9)
Exercise of employee stock options (in shares)			1,109,113
Exercise of employee stock options		14.4			14.4
Stock-based compensation activity, net of withholding for tax (in shares)	[1]		102,833
Stock-based compensation activity, net of withholding for tax	[1]	17.3			17.3
Employee 401K match with Vertiv stock (in shares)			44,968
Employee 401K match with Vertiv stock		2.2			2.2
Dividend		(9.3)				(9.3)
Repurchases of common stock (in shares)			(9,076,444)	9,076,444
Repurchase of common stock		(605.9)		$ (605.9)
Other comprehensive income (loss), net of tax		(34.3)					(34.3)
Ending balance, treasury (in shares) at Mar. 31, 2024				9,076,444
Ending balance (in shares) at Mar. 31, 2024			373,969,346
Ending balance at Mar. 31, 2024		1,393.4	$ 0.0	$ (605.9)	2,745.2	(707.1)	(38.8)
Beginning balance (in shares) at Dec. 31, 2023			381,788,876
Beginning balance at Dec. 31, 2023		2,014.9	$ 0.0	$ 0.0	2,711.3	(691.9)	(4.5)
Beginning balance, treasury (in shares) at Dec. 31, 2023				0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		348.8
Ending balance, treasury (in shares) at Sep. 30, 2024				0
Ending balance (in shares) at Sep. 30, 2024			375,249,753
Ending balance at Sep. 30, 2024		1,813.7	$ 0.0	$ 0.0	2,151.8	(371.2)	33.1
Beginning balance (in shares) at Mar. 31, 2024			373,969,346
Beginning balance at Mar. 31, 2024		1,393.4	$ 0.0	$ (605.9)	2,745.2	(707.1)	(38.8)
Beginning balance, treasury (in shares) at Mar. 31, 2024				9,076,444
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		178.1				178.1
Exercise of employee stock options (in shares)			693,261
Exercise of employee stock options		9.2			9.2
Stock-based compensation activity, net of withholding for tax (in shares)	[2]		412,459
Stock-based compensation activity, net of withholding for tax	[2]	(10.7)			(10.7)
Employee 401K match with Vertiv stock (in shares)			38,061
Employee 401K match with Vertiv stock		3.2			3.2
Dividend		(9.4)				(9.4)
Retirement of treasury stock (in shares)				(9,076,444)
Retirement of treasury stock				$ 605.9	(605.9)
Other comprehensive income (loss), net of tax		(26.3)					(26.3)
Ending balance, treasury (in shares) at Jun. 30, 2024				0
Ending balance (in shares) at Jun. 30, 2024			375,113,127
Ending balance at Jun. 30, 2024		1,537.5	$ 0.0	$ 0.0	2,141.0	(538.4)	(65.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		176.6				176.6
Exercise of employee stock options (in shares)			100,303
Exercise of employee stock options		1.4			1.4
Stock-based compensation activity, net of withholding for tax (in shares)	[3]		10,299
Stock-based compensation activity, net of withholding for tax	[3]	7.0			7.0
Employee 401K match with Vertiv stock (in shares)			26,024
Employee 401K match with Vertiv stock		2.4			2.4
Dividend		(9.4)				(9.4)
Other comprehensive income (loss), net of tax		98.2					98.2
Ending balance, treasury (in shares) at Sep. 30, 2024				0
Ending balance (in shares) at Sep. 30, 2024			375,249,753
Ending balance at Sep. 30, 2024		$ 1,813.7	$ 0.0	$ 0.0	2,151.8	(371.2)	33.1
Beginning balance (in shares) at Dec. 31, 2024		380,703,974	380,703,974
Beginning balance at Dec. 31, 2024		$ 2,434.3	$ 0.0		2,821.4	(238.3)	(148.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		164.5				164.5
Exercise of employee stock options (in shares)			109,017
Exercise of employee stock options		1.3			1.3
Stock-based compensation activity, net of withholding for tax (in shares)	[4]		169,340
Stock-based compensation activity, net of withholding for tax	[4]	4.5			4.5
Employee 401K match with Vertiv stock (in shares)			18,813
Employee 401K match with Vertiv stock		2.4			2.4
Dividend		(14.2)				(14.2)
Other comprehensive income (loss), net of tax		73.6					73.6
Ending balance (in shares) at Mar. 31, 2025			381,001,144
Ending balance at Mar. 31, 2025		$ 2,666.4	$ 0.0		2,829.6	(88.0)	(75.2)
Beginning balance (in shares) at Dec. 31, 2024		380,703,974	380,703,974
Beginning balance at Dec. 31, 2024		$ 2,434.3	$ 0.0		2,821.4	(238.3)	(148.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		$ 887.2
Ending balance (in shares) at Sep. 30, 2025		382,258,808	382,258,808
Ending balance at Sep. 30, 2025		$ 3,508.7	$ 0.0		2,883.2	606.3	19.2
Beginning balance (in shares) at Mar. 31, 2025			381,001,144
Beginning balance at Mar. 31, 2025		2,666.4	$ 0.0		2,829.6	(88.0)	(75.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		324.2				324.2
Exercise of employee stock options (in shares)			733,437
Exercise of employee stock options		11.7			11.7
Stock-based compensation activity, net of withholding for tax (in shares)	[5]		7,784
Stock-based compensation activity, net of withholding for tax	[5]	13.0			13.0
Employee 401K match with Vertiv stock (in shares)			61,463
Employee 401K match with Vertiv stock		3.9			3.9
Dividend		(14.2)				(14.2)
Other comprehensive income (loss), net of tax		120.4					120.4
Ending balance (in shares) at Jun. 30, 2025			381,803,828
Ending balance at Jun. 30, 2025		3,125.4	$ 0.0		2,858.2	222.0	45.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		398.5				398.5
Exercise of employee stock options (in shares)			415,849
Exercise of employee stock options		9.0			9.0
Stock-based compensation activity, net of withholding for tax (in shares)	[6]		16,106
Stock-based compensation activity, net of withholding for tax	[6]	13.2			13.2
Employee 401K match with Vertiv stock (in shares)			23,025
Employee 401K match with Vertiv stock		2.8			2.8
Dividend		(14.2)				(14.2)
Other comprehensive income (loss), net of tax		$ (26.0)					(26.0)
Ending balance (in shares) at Sep. 30, 2025		382,258,808	382,258,808
Ending balance at Sep. 30, 2025		$ 3,508.7	$ 0.0		$ 2,883.2	$ 606.3	$ 19.2

[1] Net stock compensation activity includes 146,095 vested shares offset by 43,262 shares withheld for taxes valued at $3.0, stock-based compensation of $9.2, and employee incentive compensation of $11.1 awarded in fully vested shares.

[2] Net stock compensation activity includes 606,060 vested shares offset by 193,601 shares withheld for taxes valued at $18.1, stock-based compensation of $8.5, and forfeitures in employee incentive compensation of $1.1.

[3] Net stock compensation activity includes 15,583 vested shares offset by 5,284 shares withheld for taxes valued at $0.4, stock-based compensation of $8.1 and forfeitures in employee incentive compensation of $0.7.

[4] Net stock compensation activity includes 239,098 vested shares offset by 69,758 shares withheld for taxes valued at $6.7 and stock-based compensation of $11.2.

[5] Net stock compensation activity includes 12,562 vested shares offset by 4,778 shares withheld for taxes valued at $0.3 and stock-based compensation of $13.3.

[6] Net stock compensation activity includes 24,519 vested shares offset by 8,413 shares withheld for taxes valued at $1.0 and stock-based compensation of $14.2.