Annual report pursuant to Section 13 and 15(d)

PENSION AND OTHER POSTRETIREMENT PLANS - Narrative (Details)

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PENSION AND OTHER POSTRETIREMENT PLANS - Narrative (Details) - USD ($)
$ in Thousands
1 Months Ended 3 Months Ended 12 Months Ended
Nov. 30, 2021
Dec. 31, 2021
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]          
Contribution plan expense     $ 9,186 $ 8,692 $ 8,176
Forecast          
Defined Benefit Plan Disclosure [Line Items]          
Non-cash charge (in excess of)   $ 30,000      
Subsequent Event          
Defined Benefit Plan Disclosure [Line Items]          
Employer contributions $ 20,000        
Benefit payments $ 178,230        
Pension          
Defined Benefit Plan Disclosure [Line Items]          
Accumulated benefit obligation     293,926 295,674  
Projected benefit obligation     293,926 318,887  
Employer contributions     16,259 16,226  
Benefit payments     $ 13,838 $ 12,110  
Return on plan assets     3.10% 6.75% 6.75%
Other Postretirement          
Defined Benefit Plan Disclosure [Line Items]          
Employer contributions     $ 507 $ 847  
Benefit payments     $ 507 $ 847  
Return on plan assets     0.00% 0.00% 0.00%
Per capita cost of health care benefits assumed for next fiscal year (as a percent)     6.50%    
Ultimate health care cost trend rate (as a percent)     4.00%