Income Taxes (Details) - USD ($) $ in Millions	Sep. 30, 2018	Jul. 02, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Deferred Tax Assets, Net	$ 49.2		$ 1.0
Operating Loss Carryforwards	590.1
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	123.9
Federal Tax Operating Loss Carryforwards, to Expire in 2023	$ 130.0
Hawaiian Telcom Holdco, Inc. [Member]
Business Acquisition [Line Items]
Deferred Tax Assets, Net		$ 44.3
Deferred Tax Liabilities, Property, Plant and Equipment		41.4
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Pension and Postretirement Benefits		11.7
Deferred Tax Assets, Operating Loss Carryforwards		$ 62.2