Purchased Credit Impaired ("PCI") Loans - Summary of PCI Loans by Category (Details) - Covered Loans $ in Thousands	Sep. 30, 2019 USD ($) rating	Dec. 31, 2018 USD ($) rating
Covered Loans [Line Items]
Recorded Investment PCI Loans	$ 95,623	$ 46,401
Construction and land development
Covered Loans [Line Items]
Weighted- Average Risk Rating1 | rating	5.75	6.03
Recorded Investment PCI Loans	$ 7,847	$ 4,548
CRE - investor owned
Covered Loans [Line Items]
Weighted- Average Risk Rating1 | rating	7.04	7.19
Recorded Investment PCI Loans	$ 39,329	$ 23,939
CRE - owner occupied
Covered Loans [Line Items]
Weighted- Average Risk Rating1 | rating	6.58	7.39
Recorded Investment PCI Loans	$ 20,435	$ 9,669
Residential real estate
Covered Loans [Line Items]
Weighted- Average Risk Rating1 | rating	6.31	6.40
Recorded Investment PCI Loans	$ 12,011	$ 6,082
real estate financing receivable [Domain]
Covered Loans [Line Items]
Recorded Investment PCI Loans	$ 79,622	$ 44,238
Commercial and industrial
Covered Loans [Line Items]
Weighted- Average Risk Rating1 | rating	5.77	6.09
Recorded Investment PCI Loans	$ 15,773	$ 2,159
Consumer and other
Covered Loans [Line Items]
Weighted- Average Risk Rating1 | rating	5.54	2.18
Recorded Investment PCI Loans	$ 228	$ 4