Restructuring and Other Related Charges (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring and other related charges		$ 35,068	$ 40,914	$ 45,847
Restructuring charges		35,068	27,897	45,847
Accrued restructuring and other related costs		25,600
Severance and Other Personnel Related Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other related charges		21,200
Restructuring charges		30,752	26,132	$ 36,000
Severance and Other Personnel Related Costs [Member] | Management Changes [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges		26,000
Severance and Other Personnel Related Costs [Member] | Owned Subscription Streaming Services Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			1,900
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other related charges		13,900
Restructuring charges	$ 9,900	4,316	1,765
Other Restructuring [Member] | AMC Networks SVOD Organizational Changes [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 13,000
National Networks [Member] | Severance and Other Personnel Related Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other related charges		11,800
National Networks [Member] | Severance and Other Personnel Related Costs [Member] | Management Changes [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges		13,500
International And Other [Member] | Severance and Other Personnel Related Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other related charges		9,400
International And Other [Member] | Severance and Other Personnel Related Costs [Member] | Management Changes [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 12,500