Consolidated Statement of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Comprehensive Income [Abstract]
Net Income	$ 33.8	$ 32.5
Other Comprehensive Income [Abstract]
Unrealized Gain on Derivatives, Net of Income Taxes of $0.1 and $-	0	0.1
Defined Benefit Pension and Other Postretirement Benefit Plans, Net of Income Taxes of $0.2 and $0.2	0.3	0.3
Total Other Comprehensive Income	0.3	0.4
Total Comprehensive Income	34.1	32.9
Less: Non-Controlling Interest in Subsidiaries	0.3	0
Comprehensive Income Attributable to ALLETE	$ 33.8	$ 32.9