Other matters - Future Commitments (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Operating Leases
2018	$ 17,933
2019	10,933
2020	9,525
2021	8,773
2022	8,263
Thereafter	53,926
Total	109,353
Programming Contracts
Recorded Unconditional Purchase Obligation [Line Items]
2018	421,602
2019	391,283
2020	302,795
2021	882
2022	626
Thereafter	715
Total	1,117,903
Purchase Obligations
Recorded Unconditional Purchase Obligation [Line Items]
2018	75,030
2019	17,436
2020	9,138
2021	2,308
2022	463
Thereafter	183
Total	$ 104,558