INCOME TAXES - Additional Information (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 148,465	$ 138,238
Carryforward not subject to expiration	49,200
Gross unrecognized tax benefits	1,014	$ 1,014	$ 1,021	$ 1,067
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	429,800
Net operating loss carryforwards subject to annual limitation	11,900
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 479,700