Revenue from Contracts with Customers - Unsatisfied Performance Obligations Period (Details)	Jun. 30, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01
Unsatisfied Performance Obligations
Expected period to recognize revenue of remaining performance obligations	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
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]: 2021-01-01
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]: 2022-01-01
Unsatisfied Performance Obligations
Expected period to recognize revenue of remaining performance obligations
Subscription services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01
Unsatisfied Performance Obligations
Expected period to recognize revenue of remaining performance obligations	6 months
Subscription services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Unsatisfied Performance Obligations
Expected period to recognize revenue of remaining performance obligations	1 year
Subscription services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Unsatisfied Performance Obligations
Expected period to recognize revenue of remaining performance obligations	1 year
Subscription services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Unsatisfied Performance Obligations
Expected period to recognize revenue of remaining performance obligations
Other business services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01
Unsatisfied Performance Obligations
Expected period to recognize revenue of remaining performance obligations	6 months
Other business services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Unsatisfied Performance Obligations
Expected period to recognize revenue of remaining performance obligations	1 year
Other business services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Unsatisfied Performance Obligations
Expected period to recognize revenue of remaining performance obligations	1 year
Other business services | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Unsatisfied Performance Obligations
Expected period to recognize revenue of remaining performance obligations
Residential Subscription | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01 | Maximum
Unsatisfied Performance Obligations
Expected period to recognize revenue of remaining performance obligations	1 year