Loans - Summary of Recorded Investment by Risk Category of Portfolio Loans by Portfolio Class and Category (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and Leases Receivable, Gross	$ 5,149,497	$ 4,350,001
Non-Covered Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	5,048,164	4,305,626
Loans and Leases Receivable, Gross	5,046,182	4,303,600
Non-Covered Loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	2,248,571	2,121,008
Non-Covered Loans | CRE - investor owned
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	1,198,308	843,728
Non-Covered Loans | CRE - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	678,046	604,498
Non-Covered Loans | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	396,370	330,097
Non-Covered Loans | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	395,828	298,944
Non-Covered Loans | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	131,041	107,351
Loans and Leases Receivable, Gross	129,059	105,325
Pass (1-6) | Non-Covered Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	4,766,655	4,025,173
Pass (1-6) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	2,035,655	1,927,782
Pass (1-6) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	1,175,396	823,128
Pass (1-6) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	648,403	563,003
Pass (1-6) | Non-Covered Loans | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	390,532	318,451
Pass (1-6) | Non-Covered Loans | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	387,610	287,802
Pass (1-6) | Non-Covered Loans | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	129,059	105,007
Watch (7) | Non-Covered Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	197,420	208,768
Watch (7) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	142,288	146,033
Watch (7) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	19,884	15,083
Watch (7) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	26,463	31,834
Watch (7) | Non-Covered Loans | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	5,774	11,580
Watch (7) | Non-Covered Loans | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	3,011	4,232
Watch (7) | Non-Covered Loans | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0	6
Classified (8 & 9) | Non-Covered Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	82,107	69,659
Classified (8 & 9) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	70,628	47,193
Classified (8 & 9) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	3,028	5,517
Classified (8 & 9) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	3,180	9,661
Classified (8 & 9) | Non-Covered Loans | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	64	66
Classified (8 & 9) | Non-Covered Loans | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	5,207	6,910
Classified (8 & 9) | Non-Covered Loans | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	$ 0	$ 312