RESTRICTED INVESTMENTS - Available for Sale Maturity Schedule (Details) - Restricted Investments [Member] - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Within one year, Amortized cost	$ 17,590
Due in five years or less, Amortized cost	71,942
Due after five years to ten years, Amortized cost	28,324
Due in more than ten years, Amortized cost	31,083
Cost basis	148,939	$ 68,683
Within one year, Fair Value	17,128
Due in five years or less, Fair Value	71,250
Due after five years to ten years, Fair Value	28,123
Due in more than ten years, Fair Value	30,768
Fair value	$ 147,269