Goodwill and Other Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,175,120	$ 3,174,658
Accumulated Amortization	2,287,535	2,260,212
Goodwill gross carrying amount	2,165,895	2,165,864
Goodwill accumulated amortization	253,536	253,536
Customer Lists and Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	645,765	645,739
Accumulated Amortization	$ 568,949	563,135
Customer Lists and Contracts [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Life (Years)	7 years
Customer Lists and Contracts [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Life (Years)	10 years
Non-competition Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 66,206	66,156
Accumulated Amortization	$ 64,712	64,647
Non-competition Agreements [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Life (Years)	3 years
Non-competition Agreements [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Life (Years)	15 years
Site Locations [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2,413,111	2,412,745
Accumulated Amortization	$ 1,615,056	1,593,805
Site Locations [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Life (Years)	15 years
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 50,038	50,018
Accumulated Amortization	$ 38,818	$ 38,625
Other [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Life (Years)	2 years
Other [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Life (Years)	15 years