Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Useful Lives for Principal Classes of Assets (Detail)

v3.19.3.a.u2
Summary of Significant Accounting Policies - Useful Lives for Principal Classes of Assets (Detail)
12 Months Ended
Dec. 31, 2019
Buildings and improvements | Minimum  
Property, Plant and Equipment [Line Items]  
Premises and equipment useful life 10 years
Buildings and improvements | Maximum  
Property, Plant and Equipment [Line Items]  
Premises and equipment useful life 30 years
Furniture and equipment | Minimum  
Property, Plant and Equipment [Line Items]  
Premises and equipment useful life 3 years
Furniture and equipment | Maximum  
Property, Plant and Equipment [Line Items]  
Premises and equipment useful life 10 years
Leasehold improvements  
Property, Plant and Equipment [Line Items]  
Premises and equipment useful life Term of lease or useful life, whichever is shorter
Software  
Property, Plant and Equipment [Line Items]  
Premises and equipment useful life 3 years