LOANS HELD FOR INVESTMENT - Portfolio Activity (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Change in the activity of loan portfolio
Balance at the beginning of the period			$ 1,313,937,000
Initial funding			412,321,000
Origination fees and discounts, net of costs			(4,709,000)
Additional funding			9,512,000
Amortizing payments			(102,000)
Loan payoffs			(92,164,000)
Origination fee accretion			2,640,000	$ 2,013,000
Balance at the end of the period	$ 1,641,435,000		1,641,435,000
Impairment charges recognized	$ 0	$ 0	$ 0	$ 0