v3.25.1
Debt and Financing Arrangements - Narrative (Details)
 6 Months Ended
Mar. 11, 2025
shares
Mar. 31, 2025
USD ($)
shares
Mar. 31, 2024
USD ($)
Mar. 31, 2025
EUR (€)
shares
Sep. 30, 2024
USD ($)
Sep. 30, 2024
EUR (€)
Line of Credit Facility [Line Items]            
Accounts payable, trade   $ 4,081,000     $ 3,014,000  
Other borrowings   $ 822,180,000     776,467,000  
Common Class A            
Line of Credit Facility [Line Items]            
Shares issued with shelf registration (in shares) | shares 1,250,000          
Common Class A | ATM Program            
Line of Credit Facility [Line Items]            
Shares issued with shelf registration (in shares) | shares 3,000,000          
Shares remaining for sale | shares   1,250,000   1,250,000    
2027 Senior Secured Notes            
Line of Credit Facility [Line Items]            
Debt issuance costs, gross   $ 4,804,000     5,249,000  
Other borrowings   $ 295,196,000     294,751,000  
Other borrowings            
Line of Credit Facility [Line Items]            
Weighted-average interest rate on outstanding borrowings (as a percent)   2.16% 2.55% 2.16%    
Other borrowings   $ 6,495,000     15,602,000  
Senior Notes 2027 | 2027 Senior Notes            
Line of Credit Facility [Line Items]            
Debt issued amount   $ 300,000,000        
Fixed interest rate (as a percent)   8.625%   8.625%    
Receivables Purchase Agreement            
Line of Credit Facility [Line Items]            
Facility limit   $ 125,000,000        
Receivables sold to purchasers   99,100,000     96,300,000  
Unsold receivables   67,807,000     58,183,000  
Principal amount of receivables sold   38,789,000 $ 34,993,000      
Factored accounts receivable, outstanding   16,215,000     15,665,000  
Revolving credit facilities | March 2020 Debt Amendment            
Line of Credit Facility [Line Items]            
Maximum amount of borrowings available   750,000,000        
Maximum borrowing amount drawn In foreign currency   $ 350,000,000        
Rate spread adjustment (as a percent)   0.10%        
Interest rate during period (as a percent)   1.50%        
Unamortized debt costs   $ 4,427,000     4,961,000  
Revolving credit facilities | March 2020 Debt Amendment | Minimum            
Line of Credit Facility [Line Items]            
Interest rate on borrowings (as a percent)   1.00%        
Line of credit facility, unused capacity, commitment fee percentage   0.15%        
Revolving credit facilities | March 2020 Debt Amendment | Maximum            
Line of Credit Facility [Line Items]            
Interest rate on borrowings (as a percent)   2.00%        
Line of credit facility, unused capacity, commitment fee percentage   0.30%        
Domestic Revolving Credit Facility | March 2020 Debt Amendment            
Line of Credit Facility [Line Items]            
Maximum available for issuance of trade and standby letters of credit   $ 75,000,000        
Outstanding borrowings   $ 495,000,000     410,527,000  
Weighted-average interest rate on outstanding borrowings (as a percent)   4.29% 4.89% 4.29%    
Foreign Line of Credit | Foreign currency debt instruments            
Line of Credit Facility [Line Items]            
Notional amount       € 0 $ 33,485,000 € 30,000,000.0
Foreign Line of Credit | Credit Facility With European Bank            
Line of Credit Facility [Line Items]            
Maximum amount of borrowings available   $ 8,658,000   8,000,000.0    
Outstanding borrowings   $ 3,912,000   € 3,600,000   € 0
Weighted-average interest rate on outstanding borrowings (as a percent)   4.60% 6.11% 4.60%    
Foreign Line of Credit | Bank Guarantees | Credit Facility With European Bank            
Line of Credit Facility [Line Items]            
Maximum amount of borrowings available   $ 20,021,000   € 18,500,000