SUBSEQUENT EVENTS (Details) (Alagasco, USD $) In Millions, unless otherwise specified	0 Months Ended
	Jan. 15, 2015	Jan. 22, 2015	Nov. 03, 2014
5.70% Notes, due January 15, 2035 | Subsequent Event
Subsequent Event [Line Items]
Repayments of notes payable	$ 34.8
Stated interest rate on debt issued	5.70%
5.368% Notes, due December 1, 2015 | Subsequent Event
Subsequent Event [Line Items]
Long-term debt		80.0
APSC
Subsequent Event [Line Items]
Public Utilities, Approved Debt Issuance, Amount			35.0
APSC | Subsequent Event
Subsequent Event [Line Items]
Requested debt issuance amount for refinancing		$ 80.0