Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill [Table Text Block]

The following table summarizes changes to goodwill by reportable segment:

	ALLETE Clean Energy			U.S. Water Services		Total
Millions
Balance as of December 31, 2015		$3.3			$127.3		$130.6
Acquired Goodwill (a)	—			3.9		3.9
Impairment Charge (b)	(3.3		)	—		(3.3		)
Balance as of December 31, 2016	—			131.2		131.2
Acquired Goodwill (a)	—			16.9		16.9
Other Adjustments (c)	—			0.2		0.2
Balance as of December 31, 2017	—				$148.3		$148.3

(a) See Note 6. Acquisitions.

(b) The facts and circumstances that led to an impairment of ALLETE Clean Energy’s goodwill primarily relate to lower estimated energy prices in periods not under PSAs. Impairment Charge is included in Operating Expenses – Other on the Consolidated Statement of Income. (See Note 1. Operations and Significant Accounting Policies.) ALLETE Clean Energy’s goodwill was primarily related to the acquisition of Storm Lake II in 2014.

(c) Finalization of purchase price accounting for U.S. Water Services’ acquisition of WEST was completed in 2017 resulting in an adjustment to the goodwill recorded at the time of the initial acquisition.

Schedule of Intangible Assets [Table Text Block]

The following table summarizes changes to intangible assets, net, for the year ended December 31, 2017:

	December 31, 2016		Additions (a)		Amortization	December 31, 2017
Millions
Intangible Assets
Definite-Lived Intangible Assets
Customer Relationships		$59.3	—		$(4.6)		$54.7
Developed Technology and Other (b)	6.3			$0.9	(0.9)	6.3
Total Definite-Lived Intangible Assets	65.6		0.9		(5.5)	61.0
Indefinite-Lived Intangible Assets
Trademarks and Trade Names	16.6		—		n/a	16.6
Total Intangible Assets		$82.2		$0.9	$(5.5)		$77.6

(a) Additions resulting from the September 1, 2017, acquisition of Tonka Water. (See Note 6. Acquisitions.)

(b) Developed Technology and Other includes patents, non-compete agreements, land easements and trade names with finite lives.