Business and Organization	12 Months Ended
Business and Organization	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Organization	Business and Organization Powell Industries, Inc. (we, us, our, Powell or the Company) was incorporated in the state of Delaware in 2004 as a successor to a Nevada company incorporated in 1968. The Nevada company was the successor to a company founded by William E. Powell in 1947, which merged into the Company in 1977. Our major subsidiaries, all of which are wholly owned, include: Powell Electrical Systems, Inc.; Powell (UK) Limited; Powell Canada Inc.; and Powell Industries International, B.V. We develop, design, manufacture and service custom-engineered equipment and systems which (1) distribute, control and monitor the flow of electrical energy and (2) provide protection to motors, transformers and other electrically powered equipment. Our principal products include integrated power control room substations (PCRs®), custom-engineered modules, electrical houses (E-Houses), traditional and arc-resistant distribution switchgear and control gear, medium-voltage circuit breakers, monitoring and control communications systems, motor control centers, switches and bus duct systems. These products are designed for application voltages ranging from 480 volts to 38,000 volts. Our products are used in the oil and gas markets, onshore and offshore production, liquefied natural gas (LNG) facilities and terminals, pipeline, refineries and petrochemical plants. Additionally, we manufacture products for the electric utility, light rail traction power as well as mining and metals, pulp and paper and other municipal, commercial and industrial markets. Our product scope includes designs tested to meet both U.S. and international standards, under both the American National Standards Institute (ANSI) and International Electrotechnical Commission (IEC). We assist customers by providing value-added services such as spare parts, field service inspection, installation, commissioning, modification and repair, retrofit and retrofill components for existing systems and replacement circuit breakers for switchgear that is obsolete or that is no longer produced by the original manufacturer. We seek to establish long-term relationships with the end users of our systems as well as the design and construction engineering firms contracted by those end users. We believe that our culture of safety and focus on customer satisfaction, along with our financial strength, allow us to continue to capitalize on opportunities in the industries we serve. References to Fiscal 2021, Fiscal 2020 and Fiscal 2019 used throughout these Notes to Consolidated Financial Statements relate to our fiscal years ended September 30, 2021, 2020 and 2019, respectively. Impact of the COVID-19 Pandemic and Oil and Gas Commodity Market Volatility on Powell The COVID-19 pandemic continues to impact global energy markets. This pandemic has negatively impacted demand, which in turn has resulted in considerable volatility across the oil and gas commodity markets. As a result, some of our industrial customers are deferring or suspending their planned capital expenditures. Certain of our customers have asked that we delay or cancel our manufacturing on their projects as their operations have been negatively impacted by this pandemic and the reduced oil and gas demand which has resulted in recognition of cancellation fees based on contract terms and the extent of our progress on the projects. We continue to work with and review the contracts with our key suppliers who have been impacted by this pandemic to ensure that we are able to meet our customer commitments. The consequences of a prolonged global economic decline could include, but are not limited to, a continued reduction in commercial and industrial activity. Accordingly, the Company cannot reasonably estimate the duration or severity of this pandemic, or the extent to which the disruption may materially impact our business, results of operations or cash flows. We will take prudent measures to maintain our strong liquidity and cash position, which may include reducing our capital expenditures and research and development costs, as well as reducing or eliminating future dividend payments.