Acquisitions - Pro Forma Consolidated Results of Operations (Details) - EarthLink $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares
Business Acquisition [Line Items]
Revenues and sales	$ 6,002.4
Operating loss	(1,559.2)
Net loss	$ (2,098.3)
Loss per share (in dollars per share) | $ / shares	$ (57.27)