Revenue - Schedule of Revenues Disaggregation by Contract Type (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Revenues	$ 382.5	$ 386.7	$ 1,146.3	$ 979.2
Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	(6.5)	(7.8)	(20.0)	(19.3)
Transferred at Point in Time [Member]
Disaggregation Of Revenue [Line Items]
Revenues	41.2	40.9	118.8	118.7
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	341.3	345.8	1,027.5	860.5
Transferred over Time [Member] | Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	0.0	0.0	0.0	0.0
Entertainment and Communications [Member] | Operating Segments
Disaggregation Of Revenue [Line Items]
Revenues	248.5	253.4	749.3	601.5
Entertainment and Communications [Member] | Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	5.3	6.5	16.5	16.4
Entertainment and Communications [Member] | Transferred at Point in Time [Member] | Operating Segments
Disaggregation Of Revenue [Line Items]
Revenues	7.7	7.9	23.6	18.3
Entertainment and Communications [Member] | Transferred over Time [Member] | Operating Segments
Disaggregation Of Revenue [Line Items]
Revenues	235.5	239.0	709.2	566.8
IT Services and Hardware [Member] | Operating Segments
Disaggregation Of Revenue [Line Items]
Revenues	140.5	141.1	417.0	397.0
IT Services and Hardware [Member] | Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Revenues	1.2	1.3	3.5	2.9
IT Services and Hardware [Member] | Transferred at Point in Time [Member] | Operating Segments
Disaggregation Of Revenue [Line Items]
Revenues	33.5	33.0	95.2	100.4
IT Services and Hardware [Member] | Transferred over Time [Member] | Operating Segments
Disaggregation Of Revenue [Line Items]
Revenues	$ 105.8	$ 106.8	$ 318.3	$ 293.7