CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2016	Sep. 30, 2015	Mar. 31, 2015
Assets
Non-utility property, accumulated depreciation and amortization	$ 7.8	$ 7.5	$ 7.2
Capitalization:
Common stock, par value (in dollars per share)	$ 1.00	$ 1.00	$ 1.00
Common stock, authorized (in shares)	70,000,000.0	70,000,000.0	70,000,000.0
Common stock, issued (in shares)	43,400,000	43,300,000	43,300,000
Common stock, outstanding (in shares)	43,400,000	43,300,000	43,300,000
Laclede Gas
Capitalization:
Common stock, par value (in dollars per share)	$ 1.00	$ 1.00	$ 1.00
Common stock, authorized (in shares)	50,000	50,000	50,000
Common stock, issued (in shares)	24,577	24,577	24,577
Common stock, outstanding (in shares)	24,577	24,577	24,577
Alagasco
Capitalization:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, authorized (in shares)	3,000,000	3,000,000	3,000,000.0
Common stock, issued (in shares)	2,000,000	2,000,000	2,000,000
Common stock, outstanding (in shares)	2,000,000	2,000,000	2,000,000