| Component: (Network and Table) | |
|---|---|
| Network | 1088 - Disclosure - Employee Benefit Plans - Weighted-average Assumptions (Detail) (http://www.baybanks.com/taxonomy/role/DisclosureEmployeeBenefitPlansWeightedaverageAssumptions) |
| Table | Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] |
| Reporting Entity [Axis] | 0001034594 (http://www.sec.gov/CIK) |
| Legal Entity | Entity [Domain] |
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | Period [Axis] | |||
|---|---|---|---|---|
2016-01-01 - 2016-12-31 | 2015-01-01 - 2015-12-31 | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans | Defined Benefit Plans and Other Postretirement Benefit Plans | |||
| Pension Plan, Defined Benefit | Other Postretirement Benefit Plan, Defined Benefit | Pension Plan, Defined Benefit | Other Postretirement Benefit Plan, Defined Benefit | |
Discount rate used for Net Periodic Pension Cost | ||||
Discount Rate used for Disclosure | ||||
Expected return on plan assets | ||||
Rate of compensation increase | ||||
Rate of compensation increase for net periodic pension cost | ||||
Expected future interest crediting rate | ||||