Loans - Maturities and Rate Sensitivity (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	$ 3,168,183	$ 3,130,669	$ 1,810,842
Fixed Rate	689,838
Floating Rate	2,478,345
Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	660,303
Fixed Rate	78,341
Floating Rate	581,962
Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,835,059
Fixed Rate	486,314
Floating Rate	1,348,745
Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	672,821
Fixed Rate	125,183
Floating Rate	547,638
Commercial & Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,130,710	1,206,452	744,380
Commercial & Industrial [Member] | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	436,154
Commercial & Industrial [Member] | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	630,935
Commercial & Industrial [Member] | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	63,621
Owner occupied commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	367,507	353,889	166,604
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	19,420
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	194,902
Owner occupied commercial real estate [Member] | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	153,185
Commerical real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	1,020,399	904,115	367,071
Commerical real estate [Member] | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	53,435
Commerical real estate [Member] | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	780,939
Commerical real estate [Member] | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	186,025
Construction, land & land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	356,207	358,813	273,125
Construction, land & land development [Member] | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	122,512
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	156,712
Construction, land & land development [Member] | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	76,983
Residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	280,236	293,483	249,591
Residential mortgage [Member] | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	19,752
Residential mortgage [Member] | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	68,554
Residential mortgage [Member] | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	191,930
Consumer and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	13,124	$ 13,917	$ 10,071
Consumer and other [Member] | Due in One Year or Less
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	9,030
Consumer and other [Member] | Due After One Year Through Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	3,017
Consumer and other [Member] | Due After Five Years
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for investment	$ 1,077