Loans - Maturities and Rate Sensitivity (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	$ 3,047,618	$ 3,130,669	$ 1,982,280
Fixed Rate	653,651
Floating Rate	2,393,967
Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	656,274
Fixed Rate	68,238
Floating Rate	588,036
Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,720,069
Fixed Rate	472,925
Floating Rate	1,247,144
Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	671,275
Fixed Rate	112,488
Floating Rate	558,787
Commercial & Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,004,414	1,206,452
Commercial & Industrial [Member] | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	418,147
Commercial & Industrial [Member] | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	549,666
Commercial & Industrial [Member] | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	36,601
Owner occupied commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	387,032	353,889
Owner occupied commercial real estate [Member] | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	30,673
Owner occupied commercial real estate [Member] | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	172,463
Owner occupied commercial real estate [Member] | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	183,896
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,109,642	904,115
Commercial real estate [Member] | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	82,748
Commercial real estate [Member] | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	796,627
Commercial real estate [Member] | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	230,267
Construction, land & land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	278,323	358,813
Construction, land & land development [Member] | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	93,302
Construction, land & land development [Member] | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	138,864
Construction, land & land development [Member] | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	46,157
Residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	256,840	293,483
Residential mortgage [Member] | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	23,489
Residential mortgage [Member] | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	59,847
Residential mortgage [Member] | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	173,504
Consumer and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	11,367	$ 13,917
Consumer and other [Member] | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	7,915
Consumer and other [Member] | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	2,602
Consumer and other [Member] | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	$ 850