Purchased Credit Impaired ("PCI") Loans - Summary of Aging of Recorded Investment in Past Due PCI Loans by Portfolio Class and Category (Details) - Covered Loans - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	$ 1,153	$ 328
90 or More Days Past Due	6,404	3,962
Total Past Due	7,557	4,290
Current	38,844	69,864
Total	46,401	74,154
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	0
90 or More Days Past Due	0	0
Total Past Due	0	0
Current	2,159	3,212
Total	2,159	3,212
CRE - investor owned
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	416	0
90 or More Days Past Due	88	3,034
Total Past Due	504	3,034
Current	23,435	39,853
Total	23,939	42,887
CRE - owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	591	0
90 or More Days Past Due	6,279	673
Total Past Due	6,870	673
Current	2,799	10,659
Total	9,669	11,332
Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	0
90 or More Days Past Due	0	0
Total Past Due	0	0
Current	4,548	5,883
Total	4,548	5,883
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	146	328
90 or More Days Past Due	37	255
Total Past Due	183	583
Current	5,899	10,198
Total	6,082	10,781
Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0	0
90 or More Days Past Due	0	0
Total Past Due	0	0
Current	4	59
Total	$ 4	$ 59