XML 117 R93.htm IDEA: XBRL DOCUMENT v3.10.0.1
PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS - Pre-tax Amortization from AOCI (Details)
$ in Millions
12 Months Ended
Sep. 30, 2018
USD ($)
Pension Plans  
Pre-tax amounts are expected to be amortized from accumulated other comprehensive income [Abstract]  
Amortization of net actuarial loss $ 9.2
Amortization of prior service (credit) cost (0.9)
Subtotal 8.3
Regulatory adjustment (8.1)
Total 0.2
Postretirement Plans  
Pre-tax amounts are expected to be amortized from accumulated other comprehensive income [Abstract]  
Amortization of net actuarial loss (0.5)
Amortization of prior service (credit) cost (0.1)
Subtotal (0.6)
Regulatory adjustment 0.6
Total 0.0
Spire Missouri | Pension Plans  
Pre-tax amounts are expected to be amortized from accumulated other comprehensive income [Abstract]  
Amortization of net actuarial loss 8.6
Amortization of prior service (credit) cost 0.9
Subtotal 9.5
Regulatory adjustment (9.3)
Total 0.2
Spire Missouri | Postretirement Plans  
Pre-tax amounts are expected to be amortized from accumulated other comprehensive income [Abstract]  
Amortization of net actuarial loss (0.5)
Amortization of prior service (credit) cost 0.3
Subtotal (0.2)
Regulatory adjustment 0.2
Total 0.0
Spire Alabama | Pension Plans  
Pre-tax amounts are expected to be amortized from accumulated other comprehensive income [Abstract]  
Amortization of net actuarial loss 0.8
Amortization of prior service (credit) cost (1.8)
Subtotal (1.0)
Regulatory adjustment 1.0
Total 0.0
Spire Alabama | Postretirement Plans  
Pre-tax amounts are expected to be amortized from accumulated other comprehensive income [Abstract]  
Amortization of net actuarial loss 0.0
Amortization of prior service (credit) cost (0.4)
Subtotal (0.4)
Regulatory adjustment 0.4
Total $ 0.0