Revenue from Contracts with Customers - Revenue by Service Offering (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenue from Contracts with Customers
Total revenue	$ 173.1	$ 173.7	$ 517.9	$ 524.4
Subscription services
Revenue from Contracts with Customers
Revenue	160.3	160.4	480.1	485.6
Other business services
Revenue from Contracts with Customers
Revenue	5.4	5.4	15.7	16.1
Other business services - Wholesale and colocation lease revenue
Revenue from Contracts with Customers
Revenue	5.0	4.8	14.6	14.4
Other revenue
Revenue from Contracts with Customers
Other revenue	7.4	7.9	22.1	22.7
Residential Subscription | Subscription services
Revenue from Contracts with Customers
Revenue	132.1	132.7	395.9	402.4
Residential Subscription | HSD
Revenue from Contracts with Customers
Revenue	90.8	84.2	265.6	251.1
Residential Subscription | Video
Revenue from Contracts with Customers
Revenue	36.1	42.4	114.0	132.8
Residential Subscription | Telephony
Revenue from Contracts with Customers
Revenue	5.2	6.1	16.3	18.5
Business Subscription | Subscription services
Revenue from Contracts with Customers
Revenue	28.2	27.7	84.2	83.2
Business Subscription | HSD
Revenue from Contracts with Customers
Revenue	19.0	18.1	56.1	53.9
Business Subscription | Video
Revenue from Contracts with Customers
Revenue	2.8	2.9	8.6	8.8
Business Subscription | Telephony
Revenue from Contracts with Customers
Revenue	$ 6.4	$ 6.7	$ 19.5	$ 20.5