Loans - Portfolio by Type and Class (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 3,071,761	$ 3,098,220	$ 3,047,618
Loans held for sale	17,673	23,989
Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	2,485,239	2,301,928	2,152,059
Loans held for sale	17,673	23,989
Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	586,522	796,292	895,559
Commercial & Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	1,148,850	1,053,925
Commercial & Industrial | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	1,066,715	904,331	823,047
Commercial & Industrial | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	82,135	149,594	181,367
Owner occupied commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	408,398	394,210
Owner occupied commercial real estate | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	312,162	264,876	249,827
Owner occupied commercial real estate | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	96,236	129,334	137,205
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	1,068,742	1,143,751
Commercial real estate | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	806,327	816,029	761,788
Commercial real estate | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	262,415	327,722	347,854
Construction, land & land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	193,856	249,704
Construction, land & land development | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	146,522	179,999	180,315
Construction, land & land development | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	47,334	69,705	98,008
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	235,089	245,191
Residential mortgage | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	138,095	127,445	128,077
Residential mortgage | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	96,994	117,746	128,763
Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	16,826	11,439
Consumer and other | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	15,418	9,248	9,005
Consumer and other | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 1,408	$ 2,191	$ 2,362