Property, Plant, and Equipment, net - Summary of Property, Plant, and Equipment, net (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 574.1	$ 504.1
Less: Accumulated depreciation	168.3	127.8
Property, plant and equipment, net	405.8	376.3
Cable-ships and submersibles
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	246.5	251.1
Equipment, furniture and fixtures, and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	214.1	148.0
Building and leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	48.9	47.3
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	36.8	32.8
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	14.3	12.9
Plant and transportation equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 13.5	$ 12.0