NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Variable Interest Entities (Narrative) (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) license	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) license
Variable Interest Entity [Line Items]
Media revenues	$ 666,534	$ 554,167	$ 1,245,423	$ 1,058,942
Income from equity and cost method investments	943	2,007	1,366	5,153
Eliminations
Variable Interest Entity [Line Items]
Media revenues	(23,020)	(21,146)	$ (41,493)	(40,046)
Consolidated VIEs, aggregated
Variable Interest Entity [Line Items]
Initial term of certain outsourcing agreements			5 years
Number of licensees as VIEs (license) | license			37		37
Media revenues	76,800	71,800	$ 148,300	136,600
Consolidated VIEs | Eliminations
Variable Interest Entity [Line Items]
Liabilities associated with the certain outsourcing agreements and purchase options	78,000		78,000		$ 72,500
Consolidated VIEs | Cunningham | Eliminations
Variable Interest Entity [Line Items]
Total payments made under the LMA excluded from liabilities	39,200		39,200		37,600
Total capital leased liabilities excluded from VIE consolidation	4,400		4,400		4,500
VIEs which are not primary beneficiary
Variable Interest Entity [Line Items]
Carrying amount	113,500		113,500		$ 18,100
Income from equity and cost method investments	$ 900	$ 2,600	$ 1,200	$ 5,500