Revenue from Contracts with Customers - Unsatisfied Performance Obligations Amount (Details) $ in Millions	Jun. 30, 2020 USD ($)
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	$ 140.2
Subscription services
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	133.5
Other business services
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	6.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	$ 42.5
Expected period to recognize revenue of remaining performance obligations	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01 | Residential Subscription | Maximum
Unsatisfied Performance Obligations
Expected period to recognize revenue of remaining performance obligations	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01 | Subscription services
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	$ 40.5
Expected period to recognize revenue of remaining performance obligations	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01 | Other business services
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	$ 2.0
Expected period to recognize revenue of remaining performance obligations	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	$ 59.0
Expected period to recognize revenue of remaining performance obligations	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Subscription services
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	$ 56.0
Expected period to recognize revenue of remaining performance obligations	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Other business services
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	$ 3.0
Expected period to recognize revenue of remaining performance obligations	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	$ 27.3
Expected period to recognize revenue of remaining performance obligations	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Subscription services
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	$ 26.0
Expected period to recognize revenue of remaining performance obligations	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Other business services
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	$ 1.3
Expected period to recognize revenue of remaining performance obligations	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	$ 11.4
Expected period to recognize revenue of remaining performance obligations
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Subscription services
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	$ 11.0
Expected period to recognize revenue of remaining performance obligations
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Other business services
Unsatisfied Performance Obligations
Expected revenue to be recognized in future periods	$ 0.4
Expected period to recognize revenue of remaining performance obligations