Loans - Summary of Aging of Recorded Investment in Past Due Portfolio Loans by Portfolio Class and Category (Details) - Non-Covered Loans - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 33,927
Current	6,092,380
Loans, including unearned loan fees	6,126,307	$ 5,314,337
Commercial and industrial
Financing Receivable, Past Due [Line Items]
Total Past Due	17,871
Current	3,134,523
Loans, including unearned loan fees	3,152,394
CRE - investor owned
Financing Receivable, Past Due [Line Items]
Total Past Due	9,680
Current	1,282,502
Loans, including unearned loan fees	1,292,182
CRE - owner occupied
Financing Receivable, Past Due [Line Items]
Total Past Due	2,356
Current	733,348
Loans, including unearned loan fees	735,704
Construction and land development
Financing Receivable, Past Due [Line Items]
Total Past Due	898
Current	473,829
Loans, including unearned loan fees	474,727
Residential real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	2,994
Current	318,798
Loans, including unearned loan fees	321,792
Other
Financing Receivable, Past Due [Line Items]
Total Past Due	128
Current	149,380
Loans, including unearned loan fees	149,508
Financial Asset, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	4,672
Financial Asset, 30 to 89 Days Past Due [Member] | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Total Past Due	1,558
Financial Asset, 30 to 89 Days Past Due [Member] | CRE - investor owned
Financing Receivable, Past Due [Line Items]
Total Past Due	164
Financial Asset, 30 to 89 Days Past Due [Member] | CRE - owner occupied
Financing Receivable, Past Due [Line Items]
Total Past Due	1,166
Financial Asset, 30 to 89 Days Past Due [Member] | Construction and land development
Financing Receivable, Past Due [Line Items]
Total Past Due	898
Financial Asset, 30 to 89 Days Past Due [Member] | Residential real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	840
Financial Asset, 30 to 89 Days Past Due [Member] | Other
Financing Receivable, Past Due [Line Items]
Total Past Due	46
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	29,255
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Total Past Due	16,313
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | CRE - investor owned
Financing Receivable, Past Due [Line Items]
Total Past Due	9,516
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | CRE - owner occupied
Financing Receivable, Past Due [Line Items]
Total Past Due	1,190
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Construction and land development
Financing Receivable, Past Due [Line Items]
Total Past Due	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Residential real estate
Financing Receivable, Past Due [Line Items]
Total Past Due	2,154
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Other
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 82