Operations and Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2015

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Supplemental Statement of Cash Flow Information [Table Text Block]

Supplemental Statement of Cash Flow Information

Consolidated Statement of Cash Flows
Year Ended December 31	2015		2014		2013
Millions
Cash Paid During the Period for Interest – Net of Amounts Capitalized		$59.0		$51.3		$47.5
Cash Paid During the Period for Income Taxes		$0.4		$5.1		$0.5
Noncash Investing and Financing Activities
Increase (Decrease) in Accounts Payable for Capital Additions to Property, Plant and Equipment	$(40.6)			$21.7		$8.3
Capitalized Asset Retirement Costs		$12.4		$22.4	$(0.7)
AFUDC–Equity		$3.3		$7.8		$4.6
ALLETE Common Stock Contributed to the Defined Benefit Pension Plan	—			$19.5	—
Contingent Consideration		$35.7	—		—

Accounts Receivable [Table Text Block]

Accounts Receivable
As of December 31	2015		2014
Millions
Trade Accounts Receivable
Billed		$105.3		$85.5
Unbilled	16.9		18.6
Less: Allowance for Doubtful Accounts	1.0		1.1
Total Accounts Receivable		$121.2		$103.0

Inventories [Table Text Block]

Inventories
As of December 31	2015			2014
Millions
Fuel (a)		$58.1			$29.0
Materials and Supplies	49.1			51.5
Raw Materials	2.7			—
Finished Goods	7.5			—
Reserve for Obsolescence	(0.3		)	—
Total Inventories		$117.1			$80.5

(a) Fuel consists primarily of coal inventory at Minnesota Power. During 2015, Minnesota Power increased its coal inventory to take advantage of favorable pricing.

Prepayments and Other Current Assets [Table Text Block]

Prepayments and Other Current Assets
As of December 31	2015		2014
Millions
Deferred Fuel Adjustment Clause		$10.6		$16.3
Construction Costs for Development Project (a)	—		48.2
Restricted Cash (b)	5.6		2.7
Other	19.5		14.8
Total Prepayments and Other Current Assets		$35.7		$82.0

(a) Construction Costs for Development Project related to ALLETE Clean Energy’s project to construct a wind energy facility which was sold in 2015. (See Note 7. Acquisitions.)

(b) Restricted Cash includes collateral deposits required under ALLETE Clean Energy’s loan agreements and collateral deposits required for U.S. Water Services’ standby letters of credit.

Other Current and Non-Current Liabilities [Table Text Block]

Other Current Liabilities
As of December 31	2015		2014
Millions
Customer Deposits		$15.1		$19.7
Power Purchase Agreements (a)	23.3		19.4
Construction Deposits Received for Development Project (b)	—		54.3
Other (c)	47.7		27.4
Total Other Current Liabilities		$86.1		$120.8

(a) Power Purchase Agreements acquired in conjunction with the ALLETE Clean Energy wind energy facilities acquisitions. (See Note 7. Acquisitions.)

(b) Construction Deposits Received for Development Project relate to ALLETE Clean Energy’s project to construct a wind energy facility which was sold in 2015. (See Note 7. Acquisitions.)

(c) Increase in 2015 includes customer refund liabilities of approximately $7 million, pending regulatory approval.

Other Non-Current Liabilities
As of December 31	2015		2014
Millions
Asset Retirement Obligation		$131.4		$109.2
Power Purchase Agreements (a)	138.1		110.7
Contingent Consideration (b)	36.6		—
Other	42.9		45.1
Total Other Non-Current Liabilities		$349.0		$265.0

(a) Power Purchase Agreements acquired in conjunction with the ALLETE Clean Energy wind energy facilities acquisitions. (See Note 7. Acquisitions.)

(b) Contingent Consideration relates to the estimated fair value of the earnings-based payment resulting from the U.S. Water Services acquisition. (See Note 7. Acquisitions and Note 10. Fair Value.)