SIGNIFICANT ACCOUNTING POLICIES - Computation and Reconciliation of Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net income (loss) as reported
Net income (loss) as reported	$ (5,288)	$ 6,915	$ 17,244	$ 15,170	$ 15,271	$ 4,910	$ 6,372	$ 3,920	$ 34,041	$ 30,473	$ (18,853)
Less: Distributed net income available to participating securities									(85)	(27)	0
Less: Undistributed net income available to participating securities									(582)	(666)	0
Numerator for basic net income per share:									33,374	29,780	(18,853)
Add: Undistributed net income allocated to participating securities									582	666	0
Less: Undistributed net income reallocated to participating securities									(579)	(662)	0
Numerator for diluted net income per share:									$ 33,377	$ 29,784	$ (18,853)
Denominator:
Weighted average shares outstanding for basic net income per share (in shares)									14,579,608	14,529,745	14,346,851
Effect of dilutive securities (in shares)									75,742	90,890	0
Weighted average shares outstanding for diluted net income per share (in shares)									14,655,350	14,620,635	14,346,851
Net income (loss) per share:
Basic (in dollars per share)	$ (0.36)	$ 0.47	$ 1.17	$ 1.02	$ 1.02	$ 0.33	$ 0.43	$ 0.26	$ 2.29	$ 2.05	$ (1.31)
Diluted (in dollars per share)	$ (0.36)	$ 0.46	$ 1.15	$ 1.01	$ 1.02	$ 0.33	$ 0.43	$ 0.26	$ 2.28	$ 2.04	$ (1.31)