LEASES - Information related to operating lease cost (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Sep. 01, 2020 ft²	Dec. 31, 2019 USD ($)	Aug. 15, 2019 ft²	Aug. 14, 2019 USD ($) ft²	Nov. 30, 2017 ft²	Aug. 31, 2017 ft²	Jul. 31, 2014
Lessee, Lease, Description [Line Items]
Term of operating lease									5 years
Operating lease renewal term									3 years
Lease rentable area (in square feet) | ft²								26,987
Extension of square footage leased | ft²						19,177
Temporary office space square footage | ft²					5,569
Term of third lease amendment lease						84 months
Term of operating lease not yet commenced						36 months
Operating lease ROU asset	$ 9,056			$ 9,376
Total operating lease liabilities	9,730
Operating lease, cost	500	$ 300
Variable lease cost	200	$ 200
Cash payments for operating leases	$ 300
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Operating lease ROU asset						$ 8,100
Total operating lease liabilities						$ 8,100
Amended Lease
Lessee, Lease, Description [Line Items]
Lease rentable area (in square feet) | ft²								13,258
Second Amendment To Lease
Lessee, Lease, Description [Line Items]
Lease rentable area (in square feet) | ft²							26,897
Forecast
Lessee, Lease, Description [Line Items]
Lease rentable area (in square feet) | ft²			46,074