Loans - Maturities and Rate Sensitivity (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	$ 3,071,761	$ 3,098,220	$ 3,047,618
Fixed Rate	610,175
Floating Rate	2,461,586
Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	706,249
Fixed Rate	109,487
Floating Rate	596,762
Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,667,621
Fixed Rate	393,018
Floating Rate	1,274,603
Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	697,891
Fixed Rate	107,670
Floating Rate	590,221
Commercial & Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,148,850	1,053,925
Commercial & Industrial | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	410,376
Commercial & Industrial | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	702,880
Commercial & Industrial | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	35,594
Owner occupied commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	408,398	394,210
Owner occupied commercial real estate | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	39,677
Owner occupied commercial real estate | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	147,336
Owner occupied commercial real estate | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	221,385
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,068,742	1,143,751
Commercial real estate | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	159,098
Commercial real estate | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	672,213
Commercial real estate | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	237,431
Construction, land & land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	193,856	249,704
Construction, land & land development | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	71,615
Construction, land & land development | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	93,899
Construction, land & land development | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	28,342
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	235,089	245,191
Residential mortgage | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	20,542
Residential mortgage | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	48,336
Residential mortgage | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	166,211
Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	16,826	$ 11,439
Consumer and other | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	4,941
Consumer and other | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	2,957
Consumer and other | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	$ 8,928