OTHER CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Other Liabilities Disclosure [Abstract]
Accrued capital costs	$ 63,001	$ 80,696
Accrued operations and maintenance expense	2,583	2,863
Accrued taxes other than income	2,528	69
Accrued interest	493	232
Current operating lease liability	586
Other	2,855	1,066
Total other current liabilities	$ 72,046	$ 84,926