Commitments and Contingencies - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) renewal_term	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Operating Leased Assets [Line Items]
Rent expense | $	$ 59.6	$ 53.1	$ 43.8
Towers
Operating Leased Assets [Line Items]
Number of renewals | renewal_term	4
Term of renewals	5 years
Towers | Minimum
Operating Leased Assets [Line Items]
Terms of leases	5 years
Towers | Maximum
Operating Leased Assets [Line Items]
Terms of leases	10 years
Other | Minimum
Operating Leased Assets [Line Items]
Terms of leases	5 years
Other | Maximum
Operating Leased Assets [Line Items]
Terms of leases	20 years