Leases Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) renewal_option	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Lessee, Lease, Description [Line Items]
Operating Leases, Rent Expense, Net		$ 162.0	$ 161.6
Present value of lease liabilities	$ 72.0
Minimum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Remaining Lease Term	1 year
Lessor, Operating Lease, Renewal Term	1 year
Lessee, Operating Lease, Renewal Term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Remaining Lease Term	30 years
Lessor, Operating Lease, Renewal Term	10 years
Lessee, Operating Lease, Renewal Term	10 years
Outside Communications Plant [Member]
Lessee, Lease, Description [Line Items]
Annual rental payments	$ 659.0
Lessee, Operating Lease, Annual Base Rent Escalator	0.50%
Lessee, Operating Lease, Remaining Lease Term	10 years 3 months 18 days
Lessee, Operating Lease, Renewal Term	5 years
Lessee, Operating Lease, Term of Contract	15 years
Lessee, Operating Lease, Discount Rate	13.90%
Lessee, Operating Lease, Number Of Renewal Options | renewal_option	4
Building [Member]
Lessee, Lease, Description [Line Items]
Lessee, Finance Lease, Number Of Renewal Options | renewal_option	3
Lessee, Finance Lease, Renewal Term	5 years
Building [Member] | Minimum
Lessee, Lease, Description [Line Items]
Lessee, Finance Lease, Annual Base Rent Escalator	2.00%
Building [Member] | Maximum
Lessee, Lease, Description [Line Items]
Lessee, Finance Lease, Annual Base Rent Escalator	3.00%
Property Lease, Twenty Year Lease Term [Member] | Building [Member]
Lessee, Lease, Description [Line Items]
Lessee, Finance Lease, Term of Contract	20 years
Lessee, Finance Lease, Annual Rental Payments	$ 6.0
Property Lease, Ten Year Lease Term [Member] | Building [Member]
Lessee, Lease, Description [Line Items]
Lessee, Finance Lease, Term of Contract	10 years