Distribution Restrictions (Detail) $ in Thousands	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Balance of permitted transfers to parent company	$ 3,874,821	$ 3,625,712
Debt ratio	7.0
Debt ratio related to actual position on senior credit facility	7.0
Available cumulative credit	$ 2,625,301
Secured Debt | Maximum
Debt Instrument [Line Items]
Secured debt ratio	4.5
Secured Debt | Maximum | LAMAR MEDIA CORP
Debt Instrument [Line Items]
Secured debt ratio	4.5