Revenues Revenue from External Customers by Geographic Areas (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation of Revenue [Line Items]
Billboard		$ 352.8	$ 360.6	$ 1,014.8	$ 1,062.8
Revenues		467.5	451.9	1,318.4	1,337.7
United States
Disaggregation of Revenue [Line Items]
Billboard		352.8	360.6	1,014.8	1,034.7
Transit		112.4	90.9	296.4	267.3
Other Revenue		2.3	0.4	7.2	0.8
Revenues	[1]	467.5	451.9	1,318.4	1,302.8
Canada
Disaggregation of Revenue [Line Items]
Revenues		$ 0.0	$ 0.0	$ 0.0	$ 34.9	[1]

[1] Revenues classifications are based on the geography of the advertising.