Business Segment Information - Selected Financial Data for the Company's Business Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Revenue	$ 435.8	$ 409.9
Operating (loss) income	(15.0)	32.6
Expenditures for long-lived assets	87.8	60.7
Depreciation and amortization	119.5	71.0
Total assets	4,098.6		$ 4,198.8
Operating Segments | Network [Member]
Segment Reporting Information [Line Items]
Revenue	243.5	242.8
Operating (loss) income	(3.1)	31.3
Expenditures for long-lived assets	81.5	55.0
Depreciation and amortization	93.4	60.8
Total assets	2,943.9		2,949.2
Operating Segments | IT Services and Hardware [Member]
Segment Reporting Information [Line Items]
Revenue	198.8	173.8
Operating (loss) income	(4.9)	8.6
Expenditures for long-lived assets	6.3	5.7
Depreciation and amortization	26.0	10.1
Total assets	819.8		842.0
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(6.5)	(6.7)
Intersegment Eliminations [Member] | Sales [Member]
Segment Reporting Information [Line Items]
Revenue	6.5	6.7
Intersegment Eliminations [Member] | Network [Member]
Segment Reporting Information [Line Items]
Revenue	4.9	4.8
Intersegment Eliminations [Member] | IT Services and Hardware [Member]
Segment Reporting Information [Line Items]
Revenue	1.6	1.9
Corporate [Member]
Segment Reporting Information [Line Items]
Operating (loss) income	(7.0)	(7.3)
Depreciation and amortization	0.1	$ 0.1
Corporate and Elimination [Member]
Segment Reporting Information [Line Items]
Total assets	$ 334.9		$ 407.6