Revenue Contract Balances (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Capitalized Contract Cost [Line Items]
Capitalized Contract Cost, Net, Beginning Balance	$ 32.4	$ 32.0	$ 30.6
Capitalized Contract Cost, Additions	21.4	23.2	23.6
Capitalized Contract Cost, Amortization	(21.8)	(22.8)	(22.2)
Capitalized Contract Cost, Net, Ending Balance	32.0	32.4	32.0
Contract with Customer, Liability, Current	1.4
Contract with Customer, Liability, Noncurrent	28.0
Fulfillment Costs [Member]
Capitalized Contract Cost [Line Items]
Capitalized Contract Cost, Net, Beginning Balance	19.5	18.6	16.5
Capitalized Contract Cost, Additions	11.8	15.3	15.6
Capitalized Contract Cost, Amortization	(14.3)	(14.4)	(13.5)
Capitalized Contract Cost, Net, Ending Balance	17.0	19.5	18.6
Cost of Acquisition [Member]
Capitalized Contract Cost [Line Items]
Capitalized Contract Cost, Net, Beginning Balance	12.9	13.4	14.1
Capitalized Contract Cost, Additions	9.6	7.9	8.0
Capitalized Contract Cost, Amortization	(7.5)	(8.4)	(8.7)
Capitalized Contract Cost, Net, Ending Balance	15.0	12.9	13.4
Entertainment and Communications [Member]
Capitalized Contract Cost [Line Items]
Capitalized Contract Cost, Net, Beginning Balance	29.1	29.1	27.7
Capitalized Contract Cost, Additions	17.8	20.5	21.8
Capitalized Contract Cost, Amortization	(19.4)	(20.5)	(20.4)
Capitalized Contract Cost, Net, Ending Balance	27.5	29.1	29.1
Entertainment and Communications [Member] | Fulfillment Costs [Member]
Capitalized Contract Cost [Line Items]
Capitalized Contract Cost, Net, Beginning Balance	17.5	17.0	15.0
Capitalized Contract Cost, Additions	9.9	13.7	14.5
Capitalized Contract Cost, Amortization	(12.9)	(13.2)	(12.5)
Capitalized Contract Cost, Net, Ending Balance	14.5	17.5	17.0
Entertainment and Communications [Member] | Cost of Acquisition [Member]
Capitalized Contract Cost [Line Items]
Capitalized Contract Cost, Net, Beginning Balance	11.6	12.1	12.7
Capitalized Contract Cost, Additions	7.9	6.8	7.3
Capitalized Contract Cost, Amortization	(6.5)	(7.3)	(7.9)
Capitalized Contract Cost, Net, Ending Balance	13.0	11.6	12.1
IT Services and Hardware [Member]
Capitalized Contract Cost [Line Items]
Capitalized Contract Cost, Net, Beginning Balance	3.3	2.9	2.9
Capitalized Contract Cost, Additions	3.6	2.7	1.8
Capitalized Contract Cost, Amortization	(2.4)	(2.3)	(1.8)
Capitalized Contract Cost, Net, Ending Balance	4.5	3.3	2.9
IT Services and Hardware [Member] | Fulfillment Costs [Member]
Capitalized Contract Cost [Line Items]
Capitalized Contract Cost, Net, Beginning Balance	2.0	1.6	1.5
Capitalized Contract Cost, Additions	1.9	1.6	1.1
Capitalized Contract Cost, Amortization	(1.4)	(1.2)	(1.0)
Capitalized Contract Cost, Net, Ending Balance	2.5	2.0	1.6
IT Services and Hardware [Member] | Cost of Acquisition [Member]
Capitalized Contract Cost [Line Items]
Capitalized Contract Cost, Net, Beginning Balance	1.3	1.3	1.4
Capitalized Contract Cost, Additions	1.7	1.1	0.7
Capitalized Contract Cost, Amortization	(1.0)	(1.1)	(0.8)
Capitalized Contract Cost, Net, Ending Balance	$ 2.0	$ 1.3	$ 1.3