LOANS AND ALLOWANCE FOR LOAN LOSSES - Risk Category of Loans by Class (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 2,201,540	$ 1,891,635
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	446,029	416,752
Mortgage warehouse
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	83,577	67,038
Real estate | Commercial real estate (including multi-family residential)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	1,045,220	891,989
Real estate | Commercial real estate construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	225,574	159,247
Real estate | 1-4 family residential (including home equity)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	283,399	246,987
Real estate | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	106,299	98,657
Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	11,442	10,965
Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	2,088,863	1,786,344
Pass | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	413,195	384,979
Pass | Mortgage warehouse
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	83,577	67,038
Pass | Real estate | Commercial real estate (including multi-family residential)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	985,254	834,781
Pass | Real estate | Commercial real estate construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	213,312	149,010
Pass | Real estate | 1-4 family residential (including home equity)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	278,224	242,208
Pass | Real estate | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	104,051	97,808
Pass | Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	11,250	10,520
Watch
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	38,505	36,793
Watch | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	12,270	11,784
Watch | Mortgage warehouse
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	0	0
Watch | Real estate | Commercial real estate (including multi-family residential)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	18,220	16,009
Watch | Real estate | Commercial real estate construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	4,790	8,124
Watch | Real estate | 1-4 family residential (including home equity)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	838	512
Watch | Real estate | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	2,248	0
Watch | Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	139	364
Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	9,779	12,636
Special Mention | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	1,698	3,344
Special Mention | Mortgage warehouse
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	0	0
Special Mention | Real estate | Commercial real estate (including multi-family residential)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	3,672	6,804
Special Mention | Real estate | Commercial real estate construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	2,426	0
Special Mention | Real estate | 1-4 family residential (including home equity)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	1,980	2,069
Special Mention | Real estate | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	0	415
Special Mention | Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	3	4
Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	64,393	55,862
Substandard | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	18,866	16,645
Substandard | Mortgage warehouse
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	0	0
Substandard | Real estate | Commercial real estate (including multi-family residential)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	38,074	34,395
Substandard | Real estate | Commercial real estate construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	5,046	2,113
Substandard | Real estate | 1-4 family residential (including home equity)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	2,357	2,198
Substandard | Real estate | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	0	434
Substandard | Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	50	77
Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	0	0
Doubtful | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	0	0
Doubtful | Mortgage warehouse
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	0	0
Doubtful | Real estate | Commercial real estate (including multi-family residential)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	0	0
Doubtful | Real estate | Commercial real estate construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	0	0
Doubtful | Real estate | 1-4 family residential (including home equity)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	0	0
Doubtful | Real estate | Residential construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	0	0
Doubtful | Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 0	$ 0