Investments (Tables)

9 Months Ended

Sep. 30, 2011

Investments [Abstract]

Long-Term Investment Portfolio [Table Text Block]

Investments	September 30, 2011	December 31, 2010
Millions
ALLETE Properties	$93.0	$94.0
Available-for-sale Securities	30.5	25.2
Other	6.0	6.8
Total Investments	$129.5	$126.0

ALLETE Properties	September 30, 2011	December 31, 2010
Millions
Land Held-for-sale Beginning Balance (January 1, 2011 and 2010, respectively)	$86.0	$74.9
Deeds to Collateralized Property	1.9	9.9
Capitalized Improvements and Other	0.1	1.2
Cost of Real Estate Sold	(0.3)	—
Land Held-for-sale Ending Balance	87.7	86.0
Long-Term Finance Receivables (net of allowances of $0.6 and $0.8)	2.0	3.7
Other	3.3	4.3
Total Real Estate Assets	$93.0	$94.0

Long-Term Finance Receivables Allowance Roll-Forward [Table Text Block]

Long-Term Finance Receivables	Real
Allowance Roll-Forward	Estate
Millions
Beginning Balance as of December 31, 2010	$0.8
Reduction to Reserve	(0.2)
Ending Balance as of September 30, 2011	$0.6