| Component: (Network and Table) | |
|---|---|
| Network | 1077 - Disclosure - Premises and Equipment Net - Components of Premises and Equipment Included in Balance Sheets (Detail) (http://www.baybanks.com/taxonomy/role/DisclosurePremisesAndEquipmentNetComponentsOfPremisesAndEquipmentIncludedInBalanceSheets) |
| Table | Property, Plant and Equipment [Table] |
| Reporting Entity [Axis] | 0001034594 (http://www.sec.gov/CIK) |
| Legal Entity | Entity [Domain] |
| Property, Plant and Equipment [Line Items] | Period [Axis] | |||||||
|---|---|---|---|---|---|---|---|---|
2016-12-31 | 2015-12-31 | |||||||
| Property, Plant and Equipment, Type [Axis] | Property, Plant and Equipment, Type [Axis] | |||||||
| Land and Improvements | Buildings and Improvements | Furniture and Equipment | Property, Plant and Equipment, Type [Domain] | Land and Improvements | Buildings and Improvements | Furniture and Equipment | Property, Plant and Equipment, Type [Domain] | |
Premises and equipment | ||||||||
Less accumulated depreciation | ( | ( | ||||||
Premises and equipment, net | 10,844,000 | 11,646,000 | ||||||