Investments (Tables)

9 Months Ended

Sep. 30, 2017

Investments [Abstract]

Other Investments [Table Text Block]

Other Investments	September 30, 2017		December 31, 2016
Millions
ALLETE Properties		$28.8		$31.7
Available-for-sale Securities (a)	21.0		18.8
Cash Equivalents	2.2		1.3
Other	3.8		3.8
Total Other Investments		$55.8		$55.6

(a) As of September 30, 2017, the aggregate amount of available-for-sale corporate and governmental debt securities maturing in one year or less was $1.1 million, in one year to less than three years was $3.2 million, in three years to less than five years was $4.2 million and in five or more years was $1.6 million.