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Summary of Significant Accounting Policies - Principles of Consolidation (Details) - Uniti [Member] - USD ($) $ in Millions | Dec. 31, 2018 | Dec. 31, 2017
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Noncontrolling Interest [Line Items] |  |
Equity method investment ownership percentage | 50.00% |
Related party accounts receivable | $ 1.8 | $ 1.2

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