Spectrum repacking reimbursements and other, net - Schedule of Non-Cash Impairment Charges (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unusual or Infrequent Items, or Both [Abstract]
Reimbursement of spectrum repacking	$ (13,180)	$ (16,974)	$ (7,400)
Property and equipment gains	0	(2,880)	(5,989)
Intangible asset impairments and other charges	3,225	9,063	0
Contract termination and other costs related to national sales	0	5,456	0
Lease exit and other charges	0	0	551
Hurricane-related losses, net	0	0	1,137
Total spectrum repacking reimbursements and other, net	$ (9,955)	$ (5,335)	$ (11,701)