Commitments and Contingencies - Narrative (Details)	3 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2021 USD ($) RenewalOption	Dec. 31, 2020 USD ($)	Sep. 07, 2021 USD ($)
Commitments And Contingencies [Line Items]
Other current liabilities		$ 45,500,000	$ 50,900,000
Other noncurrent liabilities		96,000,000.0	82,300,000
Jointly Owned Utility Plant Aggregate Construction Cost		235,000,000.0
Jointly Owned Utility Plant Amount Paid For Cable Build		$ 200,000	700,000
Up-Front Payments For Services, Upper Range, Years		25 years
Proceeds from sale of capacity, recorded in other noncurrent liabilities		$ 19,500,000	20,800,000
Proceeds from sale of capacity, recorded in other current liabilities		1,300,000	1,300,000
Liability for services to be delivered related to up-front payment received current		83,200,000	68,900,000
Letters of Credit Outstanding, Amount		16,300,000
Indemnification liability		0	0
Other Current Liabilities [Member]
Commitments And Contingencies [Line Items]
Liability for services to be delivered related to up-front payment received current		2,200,000	1,600,000
Other Noncurrent Liabilities [Member]
Commitments And Contingencies [Line Items]
Liability for services to be delivered related to up-front payment received non current		$ 57,200,000	26,200,000
Maximum [Member]
Commitments And Contingencies [Line Items]
SEA-US contract term		25 years
Indefeasible right of use of contract term		25 years
Long-term Purchase Commitments, Period		3 years
Minimum [Member]
Commitments And Contingencies [Line Items]
SEA-US contract term		15 years
Indefeasible right of use of contract term		15 years
Long-term Purchase Commitments, Period		1 year
Pole license agreement obligation [Member]
Commitments And Contingencies [Line Items]
Contract Term, in Years		10 years
Number of renewal options | RenewalOption		2
Renewal option term		5 years
Financing obligation remeasured and includes fair value step up				$ 12,200,000
Other installment financing arrangements		$ 48,700,000	38,000,000.0
Other current liabilities		$ 2,500,000	1,300,000
Data Center Financing Arrangements [Member]
Commitments And Contingencies [Line Items]
Contract Term, in Years		10 years
Number of renewal options | RenewalOption		2
Renewal option term		2 years
Financing obligation remeasured and includes fair value step up				$ 700,000
Other installment financing arrangements		$ 4,400,000	4,100,000
Other current liabilities		600,000	400,000
Other noncurrent liabilities		$ 3,800,000	$ 3,700,000
Dedicated Fiber Agreement [Member]
Commitments And Contingencies [Line Items]
Indefeasible right of use of contract term	20 years	20 years
Liability for services to be delivered related to up-front payment received		$ 33,200,000
Dedicated Fiber Agreement [Member] | Other Current Liabilities [Member]
Commitments And Contingencies [Line Items]
Liability for services to be delivered related to up-front payment received current		500,000
Dedicated Fiber Agreement [Member] | Other Noncurrent Liabilities [Member]
Commitments And Contingencies [Line Items]
Liability for services to be delivered related to up-front payment received non current		$ 32,700,000