| Basis of Presentation (Details) $ in Millions | 3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
| Sep. 30, 2019  USD ($) | Sep. 30, 2018  USD ($) | Sep. 30, 2019  USD ($)  product | Sep. 30, 2018  USD ($) | |
| Liberty | ||||
| Reimbursable amount | $ | $ 0.7 | $ 0.8 | $ 18.6 | $ 2.6 | 
| Skyhook | ||||
| Number of primary products | product | 2 | |||
| Charter | ||||
| Investment control percentage | 25.01% | |||
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- Definition The percentage of control of common stock or equity participation in the investee accounted for under the equity method of accounting. No definition available. 
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- Definition The number of primary products sold. No definition available. 
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- Definition Amount of transactions with related party during the financial reporting period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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