FAIR VALUE MEASUREMENTS (Details 4) $ in Thousands	Jun. 30, 2017 USD ($) hedge_fund	Dec. 31, 2016 USD ($)
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Number of hedge funds with reporting lag \| hedge_fund	2
Entities that calculate net asset value per share, reporting lag, percent other investments	50.00%	35.00%
Senior notes	$ 993,511	$ 992,950
Estimate Of Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior notes	$ 1,100,000	$ 1,000,000

Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16(a))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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