FAIR VALUE MEASUREMENTS (Details) (Recurring basis, USD $)
Mar. 31, 2015
Carrying Amount
 
Assets:  
United States treasury bills $ 329,990,000
Marketable equity securities 5,619,000
Liabilities:  
Debt 396,484,000
Amount of equity component of convertible notes 77,000,000
Fair Value
 
Assets:  
United States treasury bills 329,990,000
Marketable equity securities 5,619,000
Total assets 335,609,000
Liabilities:  
Debt 380,175,000
Total liabilities 380,175,000
Level 1
 
Assets:  
United States treasury bills 329,990,000
Marketable equity securities 5,619,000
Total assets 335,609,000
Liabilities:  
Debt 380,175,000
Total liabilities $ 380,175,000