Debt - March 2024 Refinancing Transactions (Details) - USD ($)		3 Months Ended				9 Months Ended
	Mar. 12, 2024	Sep. 30, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024	Apr. 16, 2024	Mar. 26, 2024	Feb. 09, 2021	Dec. 01, 2020
Debt Instrument [Line Items]
Gain on debt extinguishment, net of debt modification costs		$ 0	$ 18,000,000.0			$ 0	$ 147,200,000
Senior notes
Debt Instrument [Line Items]
Debt instrument, percent of total debt	64.00%
Line of credit | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 375,000,000.0				$ 375,000,000.0
3.50% Senior Secured Notes | Senior notes
Debt Instrument [Line Items]
Interest rate	3.50%	3.50%				3.50%		3.50%			3.50%
Debt instrument, percent of total debt	91.00%
Debt instrument, aggregate principal amount subject to repurchase under tender offer	$ 331,400,000								$ 138,400,000
Aggregate principal amount											$ 550,000,000.0
Term Loan Facility | Term loan facility
Debt Instrument [Line Items]
Debt instrument, percent of total debt	72.00%
Debt instrument, aggregate principal amount subject to repurchase under tender offer	$ 1,588,800,000									$ 529,900,000
Aggregate principal amount											$ 2,300,000,000
3.50% FLSO Senior Secured Notes | Senior notes
Debt Instrument [Line Items]
Interest rate	3.50%	3.50%				3.50%		3.50%
Aggregate principal amount	$ 267,300,000								$ 96,900,000
Principal amount repurchased and surrendered for cancellation							45,700,000
Gain on debt extinguishment, net of debt modification costs							33,000,000
3.50% FLSO Senior Secured Notes | Term loan facility
Debt Instrument [Line Items]
Debt instrument, unamortized premium		$ 39,100,000				$ 39,100,000
Gain on debt extinguishment, net of debt modification costs				$ 23,300,000	$ 56,700,000
Debt issuance cost	$ 28,400,000			$ 3,300,000
FLSO Term Loan Facility | Senior notes
Debt Instrument [Line Items]
Interest rate	3.50%
FLSO Term Loan Facility | Term loan facility
Debt Instrument [Line Items]
Aggregate principal amount	$ 1,687,200,000
Principal amount repurchased and surrendered for cancellation			24,100,000				43,400,000
Gain on debt extinguishment, net of debt modification costs			$ 18,000,000				32,100,000
FLSO Term Loan Facility | Term loan facility | Rackspace Finance LLC
Debt Instrument [Line Items]
Aggregate principal amount	1,312,000,000
FLSO Term Loan Facility | Term loan facility | New Borrower
Debt Instrument [Line Items]
Aggregate principal amount										$ 375,100,000
FLFO Term Loan Facility | Senior notes
Debt Instrument [Line Items]
Aggregate principal amount	275,000,000
FLFO Term Loan Facility | Term loan facility
Debt Instrument [Line Items]
Aggregate principal amount	275,000,000
5.375% Senior Notes | Senior notes
Debt Instrument [Line Items]
Interest rate		5.375%				5.375%		5.375%				5.375%
Aggregate principal amount												$ 550,000,000.0
Principal amount repurchased and surrendered for cancellation							2,900,000
Gain on debt extinguishment, net of debt modification costs							$ 2,100,000
5.375% Senior Notes | Senior notes | Private Exchange
Debt Instrument [Line Items]
Principal amount repurchased and surrendered for cancellation	69,300,000
New Revolving Credit Facility | Line of credit | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 375,000,000	$ 375,000,000				$ 375,000,000