Mergers and Acquisitions - Finite Lived Intangible Assets Acquired (Details) $ in Millions				9 Months Ended
		Jul. 02, 2018 USD ($)	Oct. 02, 2017 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Fair Value	[1]			$ 192.1	$ 141.8
Customer relationships
Business Acquisition [Line Items]
Fair Value	[1]			140.9	116.0
Trade name
Business Acquisition [Line Items]
Fair Value	[1]			41.3	15.9
Technology
Business Acquisition [Line Items]
Fair Value	[1]			$ 9.9	$ 9.9
Useful Lives				10 years
OnX Holdings LLC [Member]
Business Acquisition [Line Items]
Fair Value			$ 134.0
OnX Holdings LLC [Member] | Customer relationships
Business Acquisition [Line Items]
Fair Value			$ 108.0
Useful Lives			15 years
OnX Holdings LLC [Member] | Trade name
Business Acquisition [Line Items]
Fair Value			$ 16.0
Useful Lives			10 years
OnX Holdings LLC [Member] | Technology
Business Acquisition [Line Items]
Fair Value			$ 10.0
Useful Lives			10 years
Hawaiian Telcom Holdco, Inc. [Member]
Business Acquisition [Line Items]
Fair Value		$ 52.0
Hawaiian Telcom Holdco, Inc. [Member] | Customer relationships
Business Acquisition [Line Items]
Fair Value		$ 26.0
Useful Lives		15 years
Hawaiian Telcom Holdco, Inc. [Member] | Trade name
Business Acquisition [Line Items]
Fair Value		$ 26.0
Useful Lives		15 years
Hawaiian Telcom Holdco, Inc. [Member] | Technology
Business Acquisition [Line Items]
Fair Value		$ 0.0
Finite-Lived Intangible Assets, Useful Life, in Years		0

[1] Change in gross carrying amounts is due to foreign currency translation on intangible assets related to OnX and intangible assets acquired in conjunction with the merger of Hawaiian Telcom. See Note 4 for further information.