| Pay vs Performance Disclosure - USD ($) | 12 Months Ended |
| Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2021 |
| Pay vs Performance Disclosure | | | | |
| Pay vs Performance Disclosure, Table | Fiscal Summary Compensation Average Summary Average Value of Initial Fixed $100 Net Adjusted Total Peer Group (a) (b) (c) (d) (e) (f) (g) (h) (i) 2024 $7,941,844 ($5,910,997) $1,666,386 ($1,079,163) $375.57 $209.16 $472.90 $771.70 2023 $6,938,256 $25,496,127 $1,803,340 $5,502,109 $656.36 $161.74 $689.90 $1,042.10 2022 $7,410,815 $5,997,622 $1,990,860 $1,940,417 $342.32 $122.63 $913.43 $1,341.80 2021 $5,523,425 $36,672,491 $1,875,741 $7,568,505 $382.40 $139.99 $587.86 $897.60 | | | |
| Company Selected Measure Name | Adjusted EBITDA | | | |
| Named Executive Officers, Footnote | (1) The principal executive officer (PEO) for all years shown in the table is Mr. Waltz. | | | |
| Peer Group Issuers, Footnote | (5) Represents the Total Shareholder that would have been realized by an investor, assuming reinvestment of dividends, who invested $100 in the peer group at the beginning of the measurement period. The peer group used for this purpose is the S&P 400 Industrials Index. The peer group referred to throughout this Pay for Performance section is separate and distinct from the peer group referred to in the “Compensation Discussion and Analysis” above. | | | |
| PEO Total Compensation Amount | $ 7,941,844 | $ 6,938,256 | $ 7,410,815 | $ 5,523,425 |
| PEO Actually Paid Compensation Amount | $ (5,910,997) | 25,496,127 | 5,997,622 | 36,672,491 |
| Adjustment To PEO Compensation, Footnote | (3) For information on the calculation on CAP to our PEO and average CAP to our non-PEO NEOs, please see immediately following discussion. CAP to PEO Prior FYE 9/30/2020 9/30/2021 9/30/2022 9/30/2023 Current FYE 9/30/2021 9/30/2022 9/30/2023 9/30/2024 Fiscal Year 2021 2022 2023 2024 SCT Total $5,523,425 $7,410,815 $6,938,256 $7,941,844 + Grant Date Fair Value of Option Awards and Stock Awards Granted in Fiscal Year ($2,099,778) ($3,799,912) ($5,000,039) ($5,999,372) + Fair Value at Fiscal Year-End of Outstanding and Unvested Option Awards and Stock Awards Granted in Fiscal Year $9,039,942 $3,444,600 $8,216,512 $1,854,240 + Change in Fair Value of Outstanding and Unvested Option Awards and Stock Awards Granted in Prior Fiscal Years $23,678,706 ($2,017,324) $13,328,729 ($7,737,198) + Fair Value at Vesting of Option Awards and Stock Awards Granted in Fiscal Year That Vested During Fiscal Year $0 $0 $0 $0 + Change in Fair Value as of Vesting Date of Option Awards and Stock Awards Granted in Prior Fiscal Years For Which Applicable Vesting Conditions Were Satisfied During Fiscal Year $530,196 $959,443 $2,012,668 ($1,970,511) - Fair Value as of Prior Fiscal Year-End of Option Awards and Stock Awards Granted in Prior Fiscal Years That Failed to Meet Applicable Vesting Conditions During Fiscal Year $0 $0 $0 $0 Compensation Actually Paid $36,672,491 $5,997,622 $25,496,127 ($5,910,997) | | | |
| Non-PEO NEO Average Total Compensation Amount | $ 1,666,386 | 1,803,340 | 1,990,860 | 1,875,741 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ (1,079,163) | 5,502,109 | 1,940,417 | 7,568,505 |
| Adjustment to Non-PEO NEO Compensation Footnote | (3) For information on the calculation on CAP to our PEO and average CAP to our non-PEO NEOs, please see immediately following discussion. Average CAP to Non-PEO NEOs Prior FYE 9/30/2020 9/30/2021 9/30/2022 9/30/2023 Current FYE 9/30/2021 9/30/2022 9/30/2023 9/30/2024 Fiscal Year 2021 2022 2023 2024 SCT Total $1,875,741 $1,990,860 $1,803,340 $1,666,386 + Grant Date Fair Value of Option Awards and Stock Awards Granted in Fiscal Year ($662,459) ($787,501) ($1,006,234) ($975,949) + Fair Value at Fiscal Year-End of Outstanding and Unvested Option Awards and Stock Awards Granted in Fiscal Year $2,852,019 $713,877 $1,653,534 $207,880 + Change in Fair Value of Outstanding and Unvested Option Awards and Stock Awards Granted in Prior Fiscal Years $3,203,877 ($357,124) $2,439,589 ($885,396) + Fair Value at Vesting of Option Awards and Stock Awards Granted in Fiscal Year That Vested During Fiscal Year $0 $0 $0 $0 + Change in Fair Value as of Vesting Date of Option Awards and Stock Awards Granted in Prior Fiscal Years For Which Applicable Vesting Conditions Were Satisfied During Fiscal Year $299,328 $380,306 $611,881 ($411,244) - Fair Value as of Prior Fiscal Year-End of Option Awards and Stock Awards Granted in Prior Fiscal Years That Failed to Meet Applicable Vesting Conditions During Fiscal Year $0 $0 $0 ($680,840) Compensation Actually Paid $7,568,505 $1,940,417 $5,502,109 ($1,079,163) | | | |
| Compensation Actually Paid vs. Total Shareholder Return | | | | |
| Compensation Actually Paid vs. Net Income | | | | |
| Compensation Actually Paid vs. Company Selected Measure | | | | |
| Total Shareholder Return Vs Peer Group | | | | |
| Tabular List, Table | Most Important Performance Measures Adjusted EBITDA (1) Working Capital Days (1) Relative TSR (2) Adjusted Net Income (2) | | | |
| Total Shareholder Return Amount | $ 375.57 | 656.36 | 342.32 | 382.40 |
| Peer Group Total Shareholder Return Amount | 209.16 | 161.74 | 122.63 | 139.99 |
| Net Income (Loss) | $ 472,900,000 | $ 689,900,000 | $ 913,430,000 | $ 587,860,000 |
| Company Selected Measure Amount | 771,700,000 | 1,042,100,000 | 1,341,800,000 | 897,600,000 |
| PEO Name | Mr. Waltz | | | |
| Additional 402(v) Disclosure | (4) This column illustrates the cumulative Total Shareholder Return that would have been realized as of the end of the measurement period, assuming reinvestment of dividends throughout, by an investor who invested $100 in our common stock at the beginning of the measurement period. (6) The dollar amounts reported represent the amount of net income reflected in the Company’s audited financial statements for the applicable year. | | | |
| Measure:: 1 | | | | |
| Pay vs Performance Disclosure | | | | |
| Name | Adjusted EBITDA(1) | | | |
| Non-GAAP Measure Description | (7) We determined Adjusted EBITDA to be the Company Selected Measure, which in our assessment represents the most important financial performance measure not otherwise disclosed in the table that we use to link CAP to the Company’s NEOs for the most recently completed fiscal year to company performance. For more information on the calculation of Adjusted EBITDA, see “Performance Metrics Definitions” on page 32. | | | |
| Measure:: 2 | | | | |
| Pay vs Performance Disclosure | | | | |
| Name | Working Capital Days(1) | | | |
| Measure:: 3 | | | | |
| Pay vs Performance Disclosure | | | | |
| Name | Relative TSR(2) | | | |
| Measure:: 4 | | | | |
| Pay vs Performance Disclosure | | | | |
| Name | Adjusted Net Income(2) | | | |
| PEO | Stock Awards Adjustments [Member] | | | | |
| Pay vs Performance Disclosure | | | | |
| Adjustment to Compensation, Amount | $ (5,999,372) | $ (5,000,039) | $ (3,799,912) | $ (2,099,778) |
| PEO | Equity Awards Granted During the Year, Unvested [Member] | | | | |
| Pay vs Performance Disclosure | | | | |
| Adjustment to Compensation, Amount | 1,854,240 | 8,216,512 | 3,444,600 | 9,039,942 |
| PEO | Equity Awards Granted in Prior Years, Unvested [Member] | | | | |
| Pay vs Performance Disclosure | | | | |
| Adjustment to Compensation, Amount | (7,737,198) | 13,328,729 | (2,017,324) | 23,678,706 |
| PEO | Equity Awards Granted During the Year, Vested [Member] | | | | |
| Pay vs Performance Disclosure | | | | |
| Adjustment to Compensation, Amount | 0 | 0 | 0 | 0 |
| PEO | Equity Awards Granted in Prior Years, Vested [Member] | | | | |
| Pay vs Performance Disclosure | | | | |
| Adjustment to Compensation, Amount | (1,970,511) | 2,012,668 | 959,443 | 530,196 |
| PEO | Equity Awards That Failed To Meet Vesting Conditions [Member] | | | | |
| Pay vs Performance Disclosure | | | | |
| Adjustment to Compensation, Amount | 0 | 0 | 0 | 0 |
| Non-PEO NEO | Stock Awards Adjustments [Member] | | | | |
| Pay vs Performance Disclosure | | | | |
| Adjustment to Compensation, Amount | (975,949) | (1,006,234) | (787,501) | (662,459) |
| Non-PEO NEO | Equity Awards Granted During the Year, Unvested [Member] | | | | |
| Pay vs Performance Disclosure | | | | |
| Adjustment to Compensation, Amount | 207,880 | 1,653,534 | 713,877 | 2,852,019 |
| Non-PEO NEO | Equity Awards Granted in Prior Years, Unvested [Member] | | | | |
| Pay vs Performance Disclosure | | | | |
| Adjustment to Compensation, Amount | (885,396) | 2,439,589 | (357,124) | 3,203,877 |
| Non-PEO NEO | Equity Awards Granted During the Year, Vested [Member] | | | | |
| Pay vs Performance Disclosure | | | | |
| Adjustment to Compensation, Amount | 0 | 0 | 0 | 0 |
| Non-PEO NEO | Equity Awards Granted in Prior Years, Vested [Member] | | | | |
| Pay vs Performance Disclosure | | | | |
| Adjustment to Compensation, Amount | (411,244) | 611,881 | 380,306 | 299,328 |
| Non-PEO NEO | Equity Awards That Failed To Meet Vesting Conditions [Member] | | | | |
| Pay vs Performance Disclosure | | | | |
| Adjustment to Compensation, Amount | $ (680,840) | $ 0 | $ 0 | $ 0 |
