Loans - Summary of Recorded Investment by Risk Category of Portfolio Loans by Portfolio Class and Category (Details) - Non-Covered Loans - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	$ 39,623	$ 26,425
Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	22,417
Residential Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	4,408
Blanket Lien
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	405
Other Collateral
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	18
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	23,586	22,578
Commercial and industrial | Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	11,056
Commercial and industrial | Residential Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
Commercial and industrial | Blanket Lien
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	405
Commercial and industrial | Other Collateral
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
CRE - investor owned
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	9,850	2,303
CRE - investor owned | Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	9,850
CRE - investor owned | Residential Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
CRE - investor owned | Blanket Lien
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
CRE - investor owned | Other Collateral
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
CRE - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	1,511	213
CRE - owner occupied | Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	1,511
CRE - owner occupied | Residential Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
CRE - owner occupied | Blanket Lien
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
CRE - owner occupied | Other Collateral
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	200
Construction and land development | Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
Construction and land development | Residential Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	200
Construction and land development | Blanket Lien
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
Construction and land development | Other Collateral
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	4,394	1,330
Residential real estate | Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
Residential real estate | Residential Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	4,208
Residential real estate | Blanket Lien
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
Residential real estate | Other Collateral
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	82	1
Other | Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
Other | Residential Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
Other | Blanket Lien
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	0
Other | Other Collateral
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees	$ 18
Pass (1-6)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		4,954,405
Pass (1-6) | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		2,151,084
Pass (1-6) | CRE - investor owned
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		1,242,569
Pass (1-6) | CRE - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		643,276
Pass (1-6) | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		437,134
Pass (1-6) | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		348,246
Pass (1-6) | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		132,096
Watch (7)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		187,656
Watch (7) | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		124,718
Watch (7) | CRE - investor owned
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		17,572
Watch (7) | CRE - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		28,773
Watch (7) | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		12,140
Watch (7) | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		4,450
Watch (7) | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		3
Classified (8 & 9)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		81,987
Classified (8 & 9) | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		70,021
Classified (8 & 9) | CRE - investor owned
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		2,840
Classified (8 & 9) | CRE - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		6,473
Classified (8 & 9) | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		106
Classified (8 & 9) | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		2,496
Classified (8 & 9) | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		51
Total*
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		5,224,048
Total* | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		2,345,823
Total* | CRE - investor owned
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		1,262,981
Total* | CRE - owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		678,522
Total* | Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		449,380
Total* | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		355,192
Total* | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, before unearned loan fees		$ 132,150