EARNINGS PER COMMON SHARE (Tables)

9 Months Ended

Jun. 30, 2018

Earnings Per Share [Abstract]

Schedule of Earnings Per Common Share

Spire	Three Months Ended June 30,				Nine Months Ended June 30,
	2018		2017		2018		2017
Basic Earnings Per Share:
Net Income	$	25.9	$	21.7	$	240.1	$	174.9
Less: Income allocated to participating securities	0.1		0.1		0.5		0.4
Net Income Available to Common Shareholders	$	25.8	$	21.6	$	239.6	$	174.5
Weighted Average Shares Outstanding (in millions)	49.6		48.1		48.7		46.4
Basic Earnings Per Share of Common Stock	$	0.52	$	0.45	$	4.92	$	3.76
Diluted Earnings Per Share:
Net Income	$	25.9	$	21.7	$	240.1	$	174.9
Less: Income allocated to participating securities	0.1		0.1		0.5		0.4
Net Income Available to Common Shareholders	$	25.8	$	21.6	$	239.6	$	174.5
Weighted Average Shares Outstanding (in millions)	49.6		48.1		48.7		46.4
Dilutive Effect of Restricted Stock and Restricted Stock Units (in millions)*	0.1		0.1		0.1		0.2
Weighted Average Diluted Shares (in millions)	49.7		48.2		48.8		46.6
Diluted Earnings Per Share of Common Stock	$	0.52	$	0.45	$	4.91	$	3.75
* Calculation excludes certain outstanding shares (shown in millions by period at the right) attributable to stock units subject to performance or market conditions and restricted stock, which could have a dilutive effect in the future	0.4		0.4		0.4		0.4