NEW ACCOUNTING STANDARDS - Balance Sheet Impacts (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Oct. 01, 2018	Sep. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current liabilities	$ 176,033	$ 164,878	$ 123,303
Retained earnings	203,255	$ 209,132	250,707
Balance without Adoption of ASC 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current liabilities	135,774		41,575
Retained earnings	243,514		$ (41,575)
Effect of Change Higher/(Lower) | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current liabilities	40,259
Retained earnings	$ (40,259)