FINANCING ARRANGEMENTS AND LONG-TERM DEBT Short-Term Debt (Details) - USD ($)	Dec. 21, 2016	Mar. 31, 2017
Short-term Debt [Line Items]
Short-term Debt		$ 567,400,000.0
Commercial Paper Notes
Short-term Debt [Line Items]
Maximum aggregate face amount	$ 975,000,000
Debt maturity	365 days
Laclede Gas
Short-term Debt [Line Items]
Short-term Debt		282,200,000.0
Alagasco
Short-term Debt [Line Items]
Short-term Debt		$ 109,300,000.0