SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Earnings Available to Common Stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	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, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share Basic [Line Items]
Net income available to common stock holders, basic earnings per share	$ 15,334	$ 11,917	$ 16,943	$ 8,311	$ 11,855	$ 12,272	$ 11,983	$ 7,635	$ 6,861	$ 5,162	$ 5,245	$ 3,957	$ 52,505	$ 43,745	$ 21,225
Net income available to common stock holders, diluted earnings per share													$ 52,505	$ 43,745	$ 21,225
Effect of dilutive shares:
Weighted average number of shares outstanding, basic earnings per share													20,718,544	17,050,095	12,985,733
Restricted stock grants													104,106	133,990	108,192
Weighted average number of shares outstanding, diluted earnings per share													20,822,650	17,184,085	13,093,925
Basic earnings per share	$ 0.72	$ 0.56	$ 0.79	$ 0.44	$ 0.64	$ 0.71	$ 0.69	$ 0.48	$ 0.48	$ 0.39	$ 0.40	$ 0.34	$ 2.53	$ 2.57	$ 1.63
Diluted earnings per share	$ 0.72	$ 0.55	$ 0.79	$ 0.44	$ 0.72	$ 0.74	$ 0.70	$ 0.63	$ 0.48	$ 0.39	$ 0.40	$ 0.34	$ 2.52	$ 2.55	$ 1.62