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Investment in ATC (Tables)
3 Months Ended
Mar. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]  
ALLETE's Investment in ATC [Table Text Block]
ALLETE’s Investment in ATC
 
Millions
 
Equity Investment Balance as of December 31, 2016

$135.6

Cash Investments
3.1

Equity in ATC Earnings
6.1

Distributed ATC Earnings
(4.6
)
Equity Investment Balance as of March 31, 2017

$140.2