OTHER DEFERRED CHARGES (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Other deferred charges
Preliminary surveys and investigations	$ 108,824	$ 107,146
Advances to operating agents of jointly owned facilities	19,377	11,537
Other	3,870	3,852
Total other deferred charges	132,071	$ 122,535
Holcomb Station Project
Other deferred charges
Preliminary surveys and investigations	$ 89,100