ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	Aug. 28, 2018	Jul. 26, 2018	Jul. 19, 2018	Jun. 30, 2018	Dec. 31, 2017
Subsequent events
Outstanding shares of preferred stock				20,868	20,868
Subsequent events
Subsequent events
Aggregate redemption price for the preferred stock		$ 25.4
Aggregate redemption price of subordinated notes		$ 6.9
Common Stock | Subsequent events
Subsequent events
Shares issued in initial public offering			2,271,250
Shares issue price (per share)			$ 19.00
Shares exercised by underwriters			296,250
Series A preferred stock | Subsequent events
Subsequent events
Outstanding shares of preferred stock		8,559
Series B preferred stock | Subsequent events
Subsequent events
Outstanding shares of preferred stock		428
Series C preferred stock | Subsequent events
Subsequent events
Outstanding shares of preferred stock		11,881
Series D preferred stock | Subsequent events
Subsequent events
Outstanding shares of preferred stock		41,000
Make Whole Shares | Make Whole Rights | Investor Agreement | Subsequent events
Subsequent events
Shares issue price (per share)	$ 0.5
Number of days of volume weighted average price	10 days
Number of business days	20 days
Weighted average price of shares	$ 17.5627
Shares issued	128,978
Make Whole Shares | Make Whole Rights | Investor Agreement | Subsequent events | Maximum
Subsequent events
Reference price (per share)	$ 31.35