Commitment and Contingencies	6 Months Ended
Mar. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	12.Commitments and Contingencies Risk Management The Company carries general liability, auto liability, workers’ compensation, professional liability, directors’ and officers’ liability, and employee health care insurance policies. In addition, the Company carries umbrella liability insurance policies to cover claims over the liability limits contained in the primary policies. The Company’s insurance programs for workers’ compensation, general liability, auto liability and employee health care for certain employees contain self-insured retention amounts, deductibles and other coverage limits (“self-insured liability”). Claims that are not self-insured as well as claims in excess of the self-insured liability amounts are insured. The Company uses estimates in the determination of the required reserves. These estimates are based upon calculations performed by third-party actuaries, as well as examination of historical trends, and industry claims experience. The Company’s reserve for unpaid and incurred but not reported claims under these programs at March 31, 2019 was $126,865, of which $42,855 was classified in current liabilities and $84,010 was classified in non-current liabilities in the accompanying unaudited consolidated balance sheet. The Company’s reserve for unpaid and incurred but not reported claims under these programs at September 30, 2018 was $127,937, of which $34,537 was classified in current liabilities and $93,400 was classified in non-current liabilities in the accompanying consolidated balance sheet. While the ultimate amount of these claims is dependent on future developments, in management’s opinion, recorded reserves are adequate to cover these claims. The Company’s reserve for unpaid and incurred but not reported claims at March 31, 2019 includes $35,697 related to claims recoverable from third party insurance carriers. Corresponding assets of $9,107 and $26,590 are recorded as Other current assets and Other assets, respectively. Litigation Contingency From time to time, the Company is subject to legal proceedings and claims in the ordinary course of its business, principally claims made alleging injuries (including vehicle and general liability matters as well as workers compensation and property casualty claims). Such claims, even if lacking merit, can result in expenditures of significant financial and managerial resources. In the ordinary course of its business, the Company is also subject to claims involving current and/or former employees and disputes involving commercial and regulatory matters. Regulatory matters include, among other things, audits and reviews of local and federal tax compliance, safety and employment practices. Although the process of resolving regulatory matters and claims through litigation and other means is inherently uncertain, the Company is not aware of any such matter, legal proceeding or claim that it believes will have, individually or in the aggregate, a material effect on the Company, its financial condition, and results of operations or cash flows. For all legal matters, an estimated liability is established in accordance with the loss contingencies accounting guidance. This estimated liability is included in Accrued expenses and other current liabilities in the accompanying consolidated balance sheets. Stockholder Litigation On April 11, 2019, a purported class action complaint, captioned Speiser v. BrightView Holdings, Inc., was filed in federal court in the Eastern District of Pennsylvania against the Company and two of the Company’s officers. On April 16, 2019, a second purported class action complaint, captioned McComas v. BrightView Holdings, Inc., was filed in the Court of Common Pleas in Montgomery County, Pennsylvania against the Company, certain current and former officers and directors of the Company, the underwriters in the Company’s IPO, and the Company’s alleged controlling stockholders. The complaints allege violations of Section 11 of the Securities Act of 1933 against all defendants and controlling person claims under Section 15 of the Act against certain defendants. The plaintiffs purport to represent similar classes of persons who purchased BrightView stock in its IPO in July 2018 or purchased BrightView stock in the market that was traceable to the shares issued in the IPO. One or both of the complaints allege that the IPO prospectus was misleading because it allegedly failed to disclose that a portion of BrightView’s contracts were underperforming and/or represented undesirable costs to the Company and that, as a result, BrightView would implement a managed exit strategy from low margin or non-profitable contracts that would negatively impact its future revenues; and that BrightView failed to disclose an alleged labor shortage caused by the Company’s inability to hire sufficient workers through the H-2B visa program would adversely affect earnings. The Company intends to defend itself vigorously against the allegations. The Company is unable at this time to determine the amount of the possible loss or range of loss, if any, that it may incur as a result of these matters.

Commitment and Contingencies

6 Months Ended

Mar. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

12.Commitments and Contingencies

Risk Management

The Company carries general liability, auto liability, workers’ compensation, professional liability, directors’ and officers’ liability, and employee health care insurance policies. In addition, the Company carries umbrella liability insurance policies to cover claims over the liability limits contained in the primary policies. The Company’s insurance programs for workers’ compensation, general liability, auto liability and employee health care for certain employees contain self-insured retention amounts, deductibles and other coverage limits (“self-insured liability”). Claims that are not self-insured as well as claims in excess of the self-insured liability amounts are insured. The Company uses estimates in the determination of the required reserves. These estimates are based upon calculations performed by third-party actuaries, as well as examination of historical trends, and industry claims experience. The Company’s reserve for unpaid and incurred but not reported claims under these programs at March 31, 2019 was $126,865, of which $42,855 was classified in current liabilities and $84,010 was classified in non-current liabilities in the accompanying unaudited consolidated balance sheet. The Company’s reserve for unpaid and incurred but not reported claims under these programs at September 30, 2018 was $127,937, of which $34,537 was classified in current liabilities and $93,400 was classified in non-current liabilities in the accompanying consolidated balance sheet. While the ultimate amount of these claims is dependent on future developments, in management’s opinion, recorded reserves are adequate to cover these claims. The Company’s reserve for unpaid and incurred but not reported claims at March 31, 2019 includes $35,697 related to claims recoverable from third party insurance carriers. Corresponding assets of $9,107 and $26,590 are recorded as Other current assets and Other assets, respectively.

Litigation Contingency

From time to time, the Company is subject to legal proceedings and claims in the ordinary course of its business, principally claims made alleging injuries (including vehicle and general liability matters as well as workers compensation and property casualty claims). Such claims, even if lacking merit, can result in expenditures of significant financial and managerial resources. In the ordinary course of its business, the Company is also subject to claims involving current and/or former employees and disputes involving commercial and regulatory matters. Regulatory matters include, among other things, audits and reviews of local and federal tax compliance, safety and employment practices. Although the process of resolving regulatory matters and claims through litigation and other means is inherently uncertain, the Company is not aware of any such matter, legal proceeding or claim that it believes will have, individually or in the aggregate, a material effect on the Company, its financial condition, and results of operations or cash flows. For all legal matters, an estimated liability is established in accordance with the loss contingencies accounting guidance. This estimated liability is included in Accrued expenses and other current liabilities in the accompanying consolidated balance sheets.

Stockholder Litigation

On April 11, 2019, a purported class action complaint, captioned Speiser v. BrightView Holdings, Inc., was filed in federal court in the Eastern District of Pennsylvania against the Company and two of the Company’s officers. On April 16, 2019, a second purported class action complaint, captioned McComas v. BrightView Holdings, Inc., was filed in the Court of Common Pleas in Montgomery County, Pennsylvania against the Company, certain current and former officers and directors of the Company, the underwriters in the Company’s IPO, and the Company’s alleged controlling stockholders. The complaints allege violations of Section 11 of the Securities Act of 1933 against all defendants and controlling person claims under Section 15 of the Act against certain defendants. The plaintiffs purport to represent similar classes of persons who purchased BrightView stock in its IPO in July 2018 or purchased BrightView stock in the market that was traceable to the shares issued in the IPO. One or both of the complaints allege that the IPO prospectus was misleading because it allegedly failed to disclose that a portion of BrightView’s contracts were underperforming and/or represented undesirable costs to the Company and that, as a result, BrightView would implement a managed exit strategy from low margin or non-profitable contracts that would negatively impact its future revenues; and that BrightView failed to disclose an alleged labor shortage caused by the Company’s inability to hire sufficient workers through the H-2B visa program would adversely affect earnings. The Company intends to defend itself vigorously against the allegations. The Company is unable at this time to determine the amount of the possible loss or range of loss, if any, that it may incur as a result of these matters.