Revenue - Disaggregated Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 386.7	$ 255.5	$ 979.2	$ 764.5
Entertainment and Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	253.4	175.0	601.5	531.1
IT Services and Hardware [Member]
Disaggregation of Revenue [Line Items]
Revenues	141.1	87.0	397.0	252.8
Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues	(7.8)	(6.5)	(19.3)	(19.4)
Intersegment Eliminations [Member] | Entertainment and Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	6.5	5.4	16.4	16.1
Intersegment Eliminations [Member] | IT Services and Hardware [Member]
Disaggregation of Revenue [Line Items]
Revenues	1.3	1.1	2.9	3.3
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	40.9	24.0	118.7	58.5
Transferred at Point in Time [Member] | Entertainment and Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	7.9	5.6	18.3	15.8
Transferred at Point in Time [Member] | IT Services and Hardware [Member]
Disaggregation of Revenue [Line Items]
Revenues	33.0	18.4	100.4	42.7
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	345.8	231.5	860.5	706.0
Transferred over Time [Member] | Entertainment and Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	239.0	164.0	566.8	499.2
Transferred over Time [Member] | IT Services and Hardware [Member]
Disaggregation of Revenue [Line Items]
Revenues	106.8	67.5	293.7	206.8
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	116.0	85.3	285.3	259.8
Video [Member]
Disaggregation of Revenue [Line Items]
Revenues	52.4	37.7	131.3	110.5
Voice [Member]
Disaggregation of Revenue [Line Items]
Revenues	76.8	48.9	169.8	151.1
Other [Member]
Disaggregation of Revenue [Line Items]
Revenues	8.2	3.1	15.1	9.7
Consulting [Member]
Disaggregation of Revenue [Line Items]
Revenues	42.1	16.1	120.0	49.3
Cloud [Member]
Disaggregation of Revenue [Line Items]
Revenues	26.2	17.4	71.8	57.5
Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	47.0	43.9	129.1	120.7
Infrastructure Solutions [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 25.8	$ 9.6	$ 76.1	$ 25.3