Revenue from Contracts with Customers - Revenue by Service Offering (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Revenue from Contracts with Customers
Total revenue	$ 284.5	$ 287.2
Subscription services
Revenue from Contracts with Customers
Revenue	264.6	265.2
HSD
Revenue from Contracts with Customers
Revenue	136.6	127.5
Video
Revenue from Contracts with Customers
Revenue	103.4	111.0
Telephony
Revenue from Contracts with Customers
Revenue	24.6	26.7
Other business services
Revenue from Contracts with Customers
Revenue	6.5	7.1
Other business services - Wholesale and colocation lease revenue
Revenue from Contracts with Customers
Revenue	5.4	5.5
Other services
Revenue from Contracts with Customers
Other revenue	13.4	14.9
Residential Subscription
Revenue from Contracts with Customers
Total revenue	228.8	231.5
Residential Subscription \| Subscription services
Revenue from Contracts with Customers
Revenue	228.8	231.5
Residential Subscription \| HSD
Revenue from Contracts with Customers
Revenue	115.3	108.1
Residential Subscription \| Video
Revenue from Contracts with Customers
Revenue	99.5	107.4
Residential Subscription \| Telephony
Revenue from Contracts with Customers
Revenue	14.0	16.0
Business Subscription
Revenue from Contracts with Customers
Total revenue	35.8	33.7
Business Subscription \| Subscription services
Revenue from Contracts with Customers
Revenue	35.8	33.7
Business Subscription \| HSD
Revenue from Contracts with Customers
Revenue	21.3	19.4
Business Subscription \| Video
Revenue from Contracts with Customers
Revenue	3.9	3.6
Business Subscription \| Telephony
Revenue from Contracts with Customers
Revenue	$ 10.6	$ 10.7

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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