| Component: (Network and Table) | |
|---|---|
| Network | 171 - Disclosure - Employee Benefit Plans - Summary of Weighted-Average Assumptions for Disclosure (Detail) (http://www.bbgi.com/taxonomy/role/DisclosureEmployeeBenefitPlansSummaryOfWeightedAverageAssumptionsForDisclosure) |
| Table | Defined Contribution Plan [Table] |
| Reporting Entity [Axis] | 0001099160 (http://www.sec.gov/CIK) |
| Defined Contribution Plan Disclosure [Line Items] | Period [Axis] | ||
|---|---|---|---|
2016-12-31 | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] | |||
| Pension Plan [Member] | Supplemental Employee Retirement Plan [Member] | Postretirement Benefits [Member] | |
Weighted-average assumptions for Disclosure | |||
Discount rate | |||
Rate of compensation increase | |||