| Component: (Network and Table) | |
|---|---|
| Network | 039 - Disclosure - Summary of Significant Accounting Policies (Detail) (http://www.beaconroofingsupply.com/role/DisclosureSummaryOfSignificantAccountingPolicies) |
| Table | Schedule of Property, Plant and Equipment [Table] |
| Reporting Entity [Axis] | 0001124941 (http://www.sec.gov/CIK) |
| Period [Axis] | 2011-10-01 - 2012-09-30 |
| Property, Plant and Equipment [Line Items] | Range [Axis] | ||||||
|---|---|---|---|---|---|---|---|
| Maximum [Member] | Minimum [Member] | Range [Domain] | |||||
| Property, Plant and Equipment By Type [Axis] | Property, Plant and Equipment By Type [Axis] | Property, Plant and Equipment By Type [Axis] | |||||
| Buildings and Improvements | Equipment | Furniture and Fixtures | Buildings and Improvements | Equipment | Furniture and Fixtures | Leasehold Improvements | |
Estimated useful life, minimum | P40Y | P10Y | P10Y | P10Y | P3Y | P5Y | |
Estimated useful life | Shorter of the estimated useful life or the term of the lease, considering renewal options expected to be exercised. | ||||||