Consolidated Statement of Comprehensive Income (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net Income	$ 104.7	$ 97.1	$ 93.6
Other Comprehensive Income (Loss) [Abstract]
Unrealized Gain (Loss) on Securities -Net of Income Taxes of $–, $0.8 and $(0.1)	0	1.2	(0.3)
Unrealized Gain (Loss) on Derivatives - Net of Income Taxes of $–, $(0.1) and $(0.2)	0.1	(0.2)	(0.3)
Defined Benefit Pension and Other Postretirement Benefit Plans - Net of Income Taxes of $3.3, $3.9 and $(3.6)	4.8	5.9	(5.1)
Total Other Comprehensive Income (Loss)	4.9	6.9	(5.7)
Total Comprehensive Income	109.6	104.0	87.9
Less: Non-Controlling Interest in Subsidiaries	0	0	(0.2)
Comprehensive Income Attributable to ALLETE	$ 109.6	$ 104.0	$ 88.1