Loans - Summary of Recorded Investment by Risk Category of Portfolio Loans by Portfolio Class and Category (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross	$ 4,275,761	$ 4,097,050
Non-Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	4,216,081	4,024,221
Loans and Leases Receivable, Gross	4,214,996	4,022,896
Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	2,038,040	1,918,720
Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	819,427	769,275
Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	593,138	554,589
Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	300,117	303,091
Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	318,055	341,312
Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	147,304	137,234
Loans and Leases Receivable, Gross	146,219	135,909
Pass (1-6) | Non-Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	3,919,379	3,794,940
Pass (1-6) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	1,853,440	1,769,102
Pass (1-6) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	785,920	754,010
Pass (1-6) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	537,740	514,616
Pass (1-6) | Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	289,263	292,766
Pass (1-6) | Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	307,727	329,742
Pass (1-6) | Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	145,289	134,704
Watch (7) | Non-Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	220,227	152,923
Watch (7) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	128,087	94,002
Watch (7) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	28,442	10,840
Watch (7) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	49,926	34,440
Watch (7) | Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	10,301	9,983
Watch (7) | Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	2,859	3,648
Watch (7) | Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	612	10
Substandard (8) | Non-Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	75,390	75,033
Substandard (8) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	56,513	55,616
Substandard (8) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	5,065	4,425
Substandard (8) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	5,472	5,533
Substandard (8) | Non-Covered Loans | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	553	342
Substandard (8) | Non-Covered Loans | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	7,469	7,922
Substandard (8) | Non-Covered Loans | Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans, before unearned loan fees	$ 318	$ 1,195