| Component: (Network and Table) | |
|---|---|
| Network | 070 - Disclosure - Activity in Allowance for Doubtful Accounts (Detail) (http://www.beaconroofingsupply.com/role/DisclosureActivityInAllowanceForDoubtfulAccounts) |
| Table | Schedule of Accounts, Notes, Loans and Financing Receivable [Table] |
| Reporting Entity [Axis] | 0001124941 (http://www.sec.gov/CIK) |
| Legal Entity [Axis] | Entity [Domain] |
| Accounts, Notes, Loans and Financing Receivable [Line Items] | Period [Axis] | ||
|---|---|---|---|
2011-10-01 - 2012-09-30 | 2010-10-01 - 2011-09-30 | 2009-10-01 - 2010-09-30 | |
Balance at beginning of year | 13,816,000 | 11,817,000 | 13,442,000 |
Provision Additions | 4,619,000 | 7,960,000 | 4,622,000 |
Write-offs | (4,971,000) | (5,960,000) | (6,247,000) |
Balance at end of year | 13,464,000 | 13,816,000 | 11,817,000 |