Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2014

Quarterly Financial Data (Unaudited) [Abstract]

Quarterly Financial Data (Unaudited) [Table Text Block]

Quarter Ended	Mar. 31		Jun. 30		Sept. 30		Dec. 31
Millions Except Earnings Per Share
2014
Operating Revenue		$296.5		$260.7		$288.9		$290.7
Operating Income		$48.3		$28.2		$60.8		$51.5
Net Income Attributable to ALLETE		$33.5		$16.8		$41.6		$32.9
Earnings Per Share of Common Stock
Basic		$0.81		$0.40		$0.97		$0.73
Diluted		$0.80		$0.40		$0.97		$0.73
2013
Operating Revenue		$263.8		$235.6		$251.0		$268.0
Operating Income		$44.4		$24.4		$38.4		$46.9
Net Income Attributable to ALLETE		$32.5		$14.0		$25.2		$33.0
Earnings Per Share of Common Stock
Basic		$0.83		$0.36		$0.63		$0.82
Diluted		$0.83		$0.35		$0.63		$0.82