FAIR VALUE MEASUREMENTS (Details) - Recurring basis $ in Thousands	Jun. 30, 2018 USD ($)
Carrying Amount
Assets:
Marketable equity securities	$ 19,210
Total assets	19,210
Liabilities:
Debt	434,236
Total liabilities	434,236
Amount of equity component of convertible notes	77,000
Fair Value
Assets:
Marketable equity securities	19,210
Total assets	19,210
Liabilities:
Debt	393,132
Total liabilities	393,132
Level 1
Assets:
Marketable equity securities	19,210
Total assets	19,210
Liabilities:
Debt	393,132
Total liabilities	$ 393,132