LOANS - Portfolio by Type and Class (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	$ 3,136,336	$ 3,190,485	$ 3,012,275
Total loans held for sale	7,461	7,156
Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	2,684,727	2,676,491	2,282,211
Total loans held for sale	7,461	7,156
Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	451,609	513,994	730,064
Total loans held for sale	0	0
Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,038,715	1,066,266
Commercial & industrial | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	991,125	1,002,797	889,848
Commercial & industrial | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	47,590	63,469	123,134
Mortgage warehouse
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	185,849	220,230
Mortgage warehouse | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	185,849	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	435,366	415,230
Owner occupied commercial real estate | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	352,138	327,906	292,413
Owner occupied commercial real estate | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	83,228	87,324	123,182
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,068,832	1,067,779
Commercial real estate | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	861,687	823,361	809,026
Commercial real estate | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	207,145	244,418	320,005
Construction, land & land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	148,732	164,952
Construction, land & land development | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	122,274	136,998	151,114
Construction, land & land development | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	26,458	27,954	50,832
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	242,529	238,580
Residential mortgage | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	156,255	149,021	130,799
Residential mortgage | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	86,274	89,559	111,040
Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	16,313	17,448
Consumer and other | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	15,399	16,178	9,011
Consumer and other | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	$ 914	$ 1,270	$ 1,871