FAIR VALUE MEASUREMENTS - Implied fair value (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Implied fair value based on level 2 inputs
Stated value	$ 1,084,683	$ 836,582
First Lien Term Loan
Implied fair value based on level 2 inputs
Stated value	796,978	798,985
Fair value	$ 792,993	$ 773,018

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13433-108611

Name:	us-gaap_DebtInstrumentFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant