Annual report pursuant to Section 13 and 15(d)

PENSION AND OTHER POSTRETIREMENT PLANS - Weighted Average Asset Allocation and Target Allocation (Details)

v3.8.0.1
PENSION AND OTHER POSTRETIREMENT PLANS - Weighted Average Asset Allocation and Target Allocation (Details) - USD ($)
$ in Thousands
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2015
Defined Benefit Plan, Actual Plan Asset Allocations [Abstract]      
Fair value of plan assets $ 155,634 $ 151,864  
Pension      
Defined Benefit Plan, Actual Plan Asset Allocations [Abstract]      
Fair value of plan assets $ 155,634 151,864 $ 142,225
Defined Benefit Plan, Assets, Target Allocations [Abstract]      
Target allocation of plan assets (as a percent) 100.00%    
Equity securities | Pension      
Defined Benefit Plan, Actual Plan Asset Allocations [Abstract]      
Fair value of plan assets $ 77,245 58,849  
Defined Benefit Plan, Assets, Target Allocations [Abstract]      
Target allocation of plan assets (as a percent) 50.00%    
Fixed income, cash and cash equivalents | Pension      
Defined Benefit Plan, Actual Plan Asset Allocations [Abstract]      
Fair value of plan assets $ 49,008 72,495  
Defined Benefit Plan, Assets, Target Allocations [Abstract]      
Target allocation of plan assets (as a percent) 30.00%    
Other investments | Pension      
Defined Benefit Plan, Actual Plan Asset Allocations [Abstract]      
Fair value of plan assets $ 29,381 $ 20,520  
Defined Benefit Plan, Assets, Target Allocations [Abstract]      
Target allocation of plan assets (as a percent) 20.00%