Common Stock and Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2014

Common Stock and Earnings Per Share [Abstract]

Summary of Common Stock [Table Text Block]

Summary of Common Stock	Shares	Equity
	Thousands	Millions
Balance as of December 31, 2011	37,513		$705.6
Employee Stock Purchase Program	20	0.8
Invest Direct	474	19.2
Options and Stock Awards	95	6.0
Equity Issuance Program	1,275	53.1
Balance as of December 31, 2012	39,377	784.7
Employee Stock Purchase Program	16	0.7
Invest Direct	395	18.5
Options and Stock Awards	301	17.9
Equity Issuance Program	1,312	63.4
Balance as of December 31, 2013	41,401	885.2
Employee Stock Purchase Program	18	0.8
Invest Direct	378	18.9
Options and Stock Awards	78	8.0
Equity Issuance Program	1,851	90.0
Forward Sale Agreement and Issuance	1,807	85.2
Contributions to Pension	396	19.5
Balance as of December 31, 2014	45,929		$1,107.6

Reconciliation of Basic and Diluted Earnings Per Share [Table Text Block]

Reconciliation of Basic and Diluted
Earnings Per Share			Dilutive
Year Ended December 31	Basic		Securities	Diluted
Millions Except Per Share Amounts
2014
Net Income Attributable to ALLETE		$124.8			$124.8
Average Common Shares	42.9		0.2	43.1
Earnings Per Share		$2.91			$2.90
2013
Net Income Attributable to ALLETE		$104.7			$104.7
Average Common Shares	39.7		0.1	39.8
Earnings Per Share		$2.64			$2.63
2012
Net Income Attributable to ALLETE		$97.1			$97.1
Average Common Shares	37.6		—	37.6
Earnings Per Share		$2.59			$2.58