Portfolio Loans - Summary of Recorded Investment by Risk Category of Portfolio Loans by Portfolio Class and Category (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, including unearned loan fees	$ 5,314,337	$ 4,350,001
Non-Covered Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	5,226,664	4,305,626
Loans, including unearned loan fees	5,224,048	4,303,600
Non-Covered Loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,345,823	2,121,008
Non-Covered Loans | CRE - investor owned
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,262,981	843,728
Non-Covered Loans | CRE - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Total	678,522	604,498
Non-Covered Loans | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Total	449,380	330,097
Non-Covered Loans | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	355,192	298,944
Non-Covered Loans | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
Total	134,766	107,351
Loans, including unearned loan fees	132,150	105,325
Pass (1-6) | Non-Covered Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, including unearned loan fees	4,954,405	4,025,173
Pass (1-6) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,151,084	1,927,782
Pass (1-6) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,242,569	823,128
Pass (1-6) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Total	643,276	563,003
Pass (1-6) | Non-Covered Loans | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Total	437,134	318,451
Pass (1-6) | Non-Covered Loans | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	348,246	287,802
Pass (1-6) | Non-Covered Loans | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, including unearned loan fees	132,096	105,007
Watch (7) | Non-Covered Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, including unearned loan fees	187,656	208,768
Watch (7) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	124,718	146,033
Watch (7) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Credit Quality Indicator [Line Items]
Total	17,572	15,083
Watch (7) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Total	28,773	31,834
Watch (7) | Non-Covered Loans | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Total	12,140	11,580
Watch (7) | Non-Covered Loans | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,450	4,232
Watch (7) | Non-Covered Loans | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, including unearned loan fees	3	6
Classified (8 & 9) | Non-Covered Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, including unearned loan fees	81,987	69,659
Classified (8 & 9) | Non-Covered Loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	70,021	47,193
Classified (8 & 9) | Non-Covered Loans | CRE - investor owned
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,840	5,517
Classified (8 & 9) | Non-Covered Loans | CRE - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Total	6,473	9,661
Classified (8 & 9) | Non-Covered Loans | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Total	106	66
Classified (8 & 9) | Non-Covered Loans | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,496	6,910
Classified (8 & 9) | Non-Covered Loans | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, including unearned loan fees	$ 51	$ 312