v3.8.0.1
INTANGIBLE ASSETS AND GOODWILL (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Changes in goodwill [Roll Forward]      
Goodwill before cumulative loss on impairment   $ 988,056 $ 158,333
Accumulated loss on impairment   (126,056) $ (125,615)
Beginning balance after cumulative loss on impairment $ 862,000 32,718  
Loss on impairment during the year 0 (441)  
Acquisition 0 820,961  
Dispositions 0 0  
Acquisition of Charlotte 0 43  
Disposition of radio station - EMF sale 0 (266)  
Acquisition of radio station - iHeartMedia Transaction 0 11,700  
Disposition of radio station - iHeartMedia Transaction 0 (14)  
Acquisition of radio station - Beasley Transaction 0 289  
Assets held for sale 0 (2,990)  
Deconsolidation of a subsidiary 0 0  
Goodwill Acquired Through Exchange 0 0  
Adjustments to acquired goodwill (2,949) 0  
Ending balance $ 859,051 $ 862,000