Revenue - Narrative (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Sep. 07, 2021	Dec. 31, 2023	Dec. 31, 2022
Disaggregation Of Revenue [Line Items]
Payment terms for customers, lower range		30 days
Payment term for customers, upper range		120 days
Expected Revenue To Be Recognized		$ 192.5
Unearned revenue and customer deposits		72.0	$ 81.6
Other Current Liabilities [Member]
Disaggregation Of Revenue [Line Items]
Unearned revenue and customer deposits		4.1	0.2
Other Noncurrent Liabilities [Member]
Disaggregation Of Revenue [Line Items]
Contract liabilities, recognized, noncurrent		$ 79.5	0.2
Dedicated Fiber Agreement [Member]
Disaggregation Of Revenue [Line Items]
Indefeasible right of use of contract term	20 years	20 years
Revenue, Remaining Performance Obligation, Percentage		50.00%
Dedicated Fiber Agreement [Member] | Other Current Liabilities [Member]
Disaggregation Of Revenue [Line Items]
Unearned revenue and customer deposits		$ 2.1	1.4
Dedicated Fiber Agreement [Member] | Other Noncurrent Liabilities [Member]
Disaggregation Of Revenue [Line Items]
Contract liabilities, recognized, noncurrent		$ 56.5	$ 51.5
Minimum [Member]
Disaggregation Of Revenue [Line Items]
Customer contract term		1 year
SEA-US contract term		15 years
Indefeasible right of use of contract term		15 years
Maximum [Member]
Disaggregation Of Revenue [Line Items]
Customer contract term		5 years
SEA-US contract term		25 years
Indefeasible right of use of contract term		25 years
Indefeasible Right of Use, Maximum, in Years		30 years