CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 278,539	$ (1,538)
Defined benefit pension plans:
Unrecognized actuarial gain (loss)		(13,469)
Applicable income taxes		3,598
Unrecognized gain (loss) arising during period, net of income taxes	6,906	(9,871)
Settlement loss (gain) included in other expense, net		502
Applicable income taxes		(134)
Settlement loss (gain) included in other expense, net, net of income taxes	(550)	368
Foreign currency translation adjustment		(424)
Applicable income taxes		0
Foreign currency translation adjustment, net	619	(424)
Other comprehensive income (loss)	6,975	(9,927)
Comprehensive income (loss)	285,514	(11,465)
Comprehensive loss (income) attributable to noncontrolling interests		680
Comprehensive income (loss) attributable to Altice USA, Inc. stockholders	$ 281,111	$ (10,785)