Loans - Portfolio by Type and Class (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 3,168,183	$ 3,130,669	$ 1,810,842
Loans held for sale		384
Originated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	2,075,548	1,933,557
Loans held for sale		384
Acquired [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	1,092,635	1,197,112
Commercial & Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	1,130,710	1,206,452	744,380
Commercial & Industrial [Member] | Originated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	847,538	850,048
Commercial & Industrial [Member] | Acquired [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	283,172	356,404
Owner occupied commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	367,507	353,889	166,604
Owner occupied commercial real estate [Member] | Originated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	205,050	188,908
Owner occupied commercial real estate [Member] | Acquired [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	162,457	164,981
Commerical real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	1,020,399	904,115	367,071
Commerical real estate [Member] | Originated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	636,539	521,887
Commerical real estate [Member] | Acquired [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	383,860	382,228
Construction, land & land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	356,207	358,813	273,125
Construction, land & land development [Member] | Originated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	252,642	242,611
Construction, land & land development [Member] | Acquired [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	103,565	116,202
Residential mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	280,236	293,483	249,591
Residential mortgage [Member] | Originated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	123,941	120,260
Residential mortgage [Member] | Acquired [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	156,295	173,223
Consumer and other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	13,124	13,917	$ 10,071
Consumer and other [Member] | Originated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	9,838	9,843
Consumer and other [Member] | Acquired [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 3,286	$ 4,074