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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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+ References

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The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Agreement amount for completing the build-out of the network.

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Asset Sales (Details) - USD ($) $ in Millions				12 Months Ended
Asset Sales (Details) - USD ($) $ in Millions	Aug. 01, 2017	Jan. 12, 2017	Jan. 12, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Asset Sales
Net proceeds from sale of assets						$ 213.0
Gain (loss) on sale of assets						38.4
Lawrence, Kansas System
Asset Sales
Period of time in which results are included in financial statements		12 days
Network elements related to Construction Services Agreement \| Disposal Group Disposed of by Sale, Not Discontinued Operations
Asset Sales
Gain (loss) on sale of assets				$ 3.3	$ 2.0	$ 0.4
MidCo \| Lawrence, Kansas System \| Disposal Group Disposed of by Sale, Not Discontinued Operations
Asset Sales
Net proceeds from sale of assets			$ 213.0
Gain (loss) on sale of assets			$ 38.4
Verizon \| Chicago Fiber Network \| Disposal Group Disposed of by Sale, Not Discontinued Operations
Asset Sales
Net proceeds from sale of assets	$ 225.0
Gain (loss) on sale of assets	93.7
Agreement amount for build-out of network	$ 50.0