Loans - Summary of Recorded Investment by Risk Category of Portfolio Loans by Portfolio Class and Category (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 4,190,845	$ 4,097,050
Non-Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	4,125,153	4,024,221
Loans and Leases Receivable, Gross	4,124,239	4,022,896
Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	1,981,684	1,918,720
Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	811,244	769,275
Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	568,773	554,589
Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	306,824	303,091
Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	328,192	341,312
Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	128,436	137,234
Loans and Leases Receivable, Gross	127,522	135,909
Pass (1-6) | Non-Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	3,882,650	3,794,940
Pass (1-6) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	1,823,444	1,769,102
Pass (1-6) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	784,937	754,010
Pass (1-6) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	534,493	514,616
Pass (1-6) | Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	295,632	292,766
Pass (1-6) | Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	317,750	329,742
Pass (1-6) | Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	126,394	134,704
Watch (7) | Non-Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	163,060	152,923
Watch (7) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	99,251	94,002
Watch (7) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	21,371	10,840
Watch (7) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	28,834	34,440
Watch (7) | Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	10,989	9,983
Watch (7) | Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	2,606	3,648
Watch (7) | Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	9	10
Substandard (8) | Non-Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	78,529	75,033
Substandard (8) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	58,989	55,616
Substandard (8) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	4,936	4,425
Substandard (8) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	5,446	5,533
Substandard (8) | Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	203	342
Substandard (8) | Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	7,836	7,922
Substandard (8) | Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	$ 1,119	$ 1,195