Summary of Significant Accounting Policies - Premises and Equipment Estimated Useful Lives (Detail)
12 Months Ended
Dec. 31, 2014
Leasehold Improvements [Member]  
Summary Of Significant Accounting Policies [Line Items]  
Estimated useful life 18 years
Computer Equipment [Member]  
Summary Of Significant Accounting Policies [Line Items]  
Estimated useful life 3 years
Minimum [Member] | Building and Improvements [Member]  
Summary Of Significant Accounting Policies [Line Items]  
Estimated useful life 10 years
Minimum [Member] | Furniture and Equipment [Member]  
Summary Of Significant Accounting Policies [Line Items]  
Estimated useful life 5 years
Maximum [Member] | Building and Improvements [Member]  
Summary Of Significant Accounting Policies [Line Items]  
Estimated useful life 40 years
Maximum [Member] | Furniture and Equipment [Member]  
Summary Of Significant Accounting Policies [Line Items]  
Estimated useful life 10 years