LOANS - Portfolio by Type and Class (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	$ 3,222,108	$ 3,190,485	$ 3,123,355
Total loans held for sale	4,992	7,156
Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	2,878,964	2,676,491	2,476,754
Total loans held for sale	4,992	7,156
Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	343,144	513,994	646,601
Total loans held for sale	0	0
Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,070,420	1,066,266
Commercial & industrial | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,034,821	1,002,797
Commercial & industrial | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	35,599	63,469	91,978
Mortgage warehouse
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	244,041	220,230
Mortgage warehouse | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	244,041	220,230
Mortgage warehouse | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	0	0
Owner occupied commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	436,153	415,230
Owner occupied commercial real estate | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	373,692	327,906	306,514
Owner occupied commercial real estate | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	62,461	87,324	100,803
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,092,036	1,067,779
Commercial real estate | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	949,099	823,361	807,341
Commercial real estate | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	142,937	244,418	301,896
Construction, land & land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	130,533	164,952
Construction, land & land development | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	105,926	136,998	153,522
Construction, land & land development | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	24,607	27,954	48,470
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	235,192	238,580
Residential mortgage | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	158,531	149,021	137,918
Residential mortgage | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	76,661	89,559	101,916
Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	13,733	17,448
Consumer and other | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	12,854	16,178	19,105
Consumer and other | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	$ 879	$ 1,270	$ 1,538