Business Segments (Tables)

6 Months Ended

Jun. 30, 2017

Segment Reporting [Abstract]

Business Segments [Table Text Block]

	Quarter Ended					Six Months Ended
	June 30,					June 30,
	2017		2016			2017			2016
Millions
Operating Revenue
Regulated Operations	$264.9		$234.9			$546.5			$487.2
Energy Infrastructure and Related Services
ALLETE Clean Energy	19.6		18.8			43.3			42.4
U.S. Water Services	38.4		34.3			70.5			66.7
Corporate and Other	30.4		26.8			58.6			52.3
Total Operating Revenue		$353.3		$314.8			$718.9			$648.6
Net Income (Loss) Attributable to ALLETE
Regulated Operations		$32.4		$22.6			$75.9			$65.0
Energy Infrastructure and Related Services
ALLETE Clean Energy	3.8		2.6			10.5			8.7
U.S. Water Services	0.6		1.0			0.3			0.5
Corporate and Other	0.1		(1.4		)	(0.8		)	(3.5		)
Total Net Income Attributable to ALLETE		$36.9		$24.8			$85.9			$70.7

	June 30, 2017		December 31, 2016
Millions
Assets
Regulated Operations	$3,824.8		$3,823.9
Energy Infrastructure and Related Services
ALLETE Clean Energy	559.1		566.0
U.S. Water Services	267.0		264.1
Corporate and Other	280.6		222.9
Total Assets		$4,931.5		$4,876.9