Revenue - Disaggregated Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 296.8	$ 259.4	$ 592.5	$ 509.0
Entertainment and Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	173.9	181.0	348.1	356.1
IT Services and Hardware [Member]
Disaggregation of Revenue [Line Items]
Revenues	128.3	84.8	255.9	165.8
Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues	(5.4)	(6.4)	(11.5)	(12.9)
Intersegment Eliminations [Member] | Entertainment and Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	4.7	5.3	9.9	10.7
Intersegment Eliminations [Member] | IT Services and Hardware [Member]
Disaggregation of Revenue [Line Items]
Revenues	0.7	1.1	1.6	2.2
Consolidation, Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	37.7	18.7	77.8	34.5
Transferred at Point in Time [Member] | Entertainment and Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	5.6	5.1	10.4	10.2
Transferred at Point in Time [Member] | IT Services and Hardware [Member]
Disaggregation of Revenue [Line Items]
Revenues	32.1	13.6	67.4	24.3
Transferred at Point in Time [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenues	259.1	240.7	514.7	474.5
Transferred over Time [Member] | Entertainment and Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	163.6	170.6	327.8	335.2
Transferred over Time [Member] | IT Services and Hardware [Member]
Disaggregation of Revenue [Line Items]
Revenues	95.5	70.1	186.9	139.3
Transferred over Time [Member] | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
Data [Member]
Disaggregation of Revenue [Line Items]
Revenues	84.4	90.1	169.3	174.5
Video [Member]
Disaggregation of Revenue [Line Items]
Revenues	39.7	36.9	78.9	72.8
Voice [Member]
Disaggregation of Revenue [Line Items]
Revenues	46.0	50.5	93.0	102.2
Other [Member]
Disaggregation of Revenue [Line Items]
Revenues	3.8	3.5	6.9	6.6
Consulting [Member]
Disaggregation of Revenue [Line Items]
Revenues	39.8	16.5	77.9	33.2
Cloud [Member]
Disaggregation of Revenue [Line Items]
Revenues	23.0	19.2	45.6	40.1
Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	41.5	40.3	82.1	76.8
Infrastructure Solutions [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 24.0	$ 8.8	$ 50.3	$ 15.7