SEGMENT REPORTING - Total Assets by Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Segment reporting information
Total assets	$ 1,162,603	$ 1,476,359
Specialty
Segment reporting information
Total assets	968,956	1,045,174
PBM
Segment reporting information
Total assets	$ 193,647	$ 431,185