Revenue recognition (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues
Total revenue	$ 34,791	$ 35,180	$ 63,826	$ 68,339
Affiliate fees
Revenues
Total revenue	19,511	19,534	$ 37,944	38,987
Revenue, remaining performance obligation, expected timing of satisfaction, period			60 days
Advertising revenue
Revenues
Total revenue	14,766	14,877	$ 24,684	28,444
Revenue, remaining performance obligation, expected timing of satisfaction, period			30 days
Other
Revenues
Total revenue	$ 514	$ 769	$ 1,198	$ 908