Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Current Assets
Cash and Cash Equivalents	$ 97.0	$ 145.8
Accounts Receivable (Less Allowance of $1.0 and $1.1)	121.2	103.0
Inventories	117.1	80.5
Prepayments and Other	35.7	82.0
Deferred Income Taxes	0.0	7.5
Total Current Assets	371.0	418.8
Property, Plant and Equipment – Net	3,669.1	3,284.8
Regulatory Assets	372.0	357.3
Investment in ATC	124.5	121.1
Other Investments	74.6	114.4
Goodwill and Intangible Assets – Net	215.2	4.8
Other Non-Current Assets	80.7	59.6
Total Assets	4,907.1	4,360.8
Current Liabilities [Abstract]
Accounts Payable	88.8	134.1
Accrued Taxes	44.0	38.7
Accrued Interest	18.6	18.0
Long-Term Debt Due Within One Year	36.3	100.7
Notes Payable	1.6	3.7
Other	86.1	120.8
Total Current Liabilities	275.4	416.0
Long-Term Debt	1,568.7	1,272.8
Deferred Income Taxes	579.8	510.7
Regulatory Liabilities	105.0	94.2
Defined Benefit Pension and Other Postretirement Benefit Plans	206.8	190.9
Other Non-Current Liabilities	349.0	265.0
Total Liabilities	$ 3,084.7	$ 2,749.6
Commitments, Guarantees and Contingencies (Note 12)
ALLETE's Equity [Abstract]
Common Stock Without Par Value, 80.0 Shares Authorized, 49.1 and 45.9 Shares Outstanding	$ 1,271.4	$ 1,107.6
Unearned ESOP Shares	0.0	(7.2)
Accumulated Other Comprehensive Loss	(24.5)	(21.1)
Retained Earnings	573.3	530.1
Total ALLETE Equity	1,820.2	1,609.4
Non-Controlling Interest in Subsidiaries	2.2	1.8
Total Equity	1,822.4	1,611.2
Total Liabilities and Equity	$ 4,907.1	$ 4,360.8