Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment and Estimated Useful Lives of Property, Plant and Equipment [Table Text Block]

Property, Plant and Equipment
As of December 31	2016			2015
Millions
Regulated Operations
Property, Plant and Equipment in Service		$4,437.0			$4,336.7
Construction Work in Progress	84.2			101.2
Accumulated Depreciation	(1,426.1		)	(1,323.8		)
Regulated Operations – Net	3,095.1			3,114.1
ALLETE Clean Energy
Property, Plant and Equipment in Service	472.3			467.3
Construction Work in Progress (a)	101.0			4.0
Accumulated Depreciation	(41.0		)	(24.0		)
ALLETE Clean Energy – Net	532.3			447.3
U.S. Water Services
Property, Plant and Equipment in Service	19.5			15.6
Accumulated Depreciation	(6.9		)	(3.4		)
U.S. Water Services – Net	12.6			12.2
Corporate and Other (b)
Property, Plant and Equipment in Service	179.8			165.6
Construction Work in Progress	2.8			4.5
Accumulated Depreciation	(81.4		)	(74.6		)
Corporate and Other – Net	101.2			95.5
Property, Plant and Equipment – Net		$3,741.2			$3,669.1

(a) The increase in ALLETE Clean Energy’s construction work in progress primarily relates to deposits for WTGs. The WTGs will be utilized as ALLETE Clean Energy develops future projects.

(b) Primarily includes BNI Energy and a small amount of non-rate base generation.

Estimated Useful Lives of Property, Plant and Equipment
Regulated Operations		ALLETE Clean Energy (a)	5 to 35 years
Generation	10 to 50 years	U.S. Water Services	3 to 39 years
Transmission	44 to 67 years	Corporate and Other	3 to 47 years
Distribution	18 to 65 years

Asset Retirement Obligations [Table Text Block]

Asset Retirement Obligations
Millions
Obligation as of December 31, 2014		$109.2
Accretion	7.3
Liabilities Recognized (a)	5.1
Liabilities Settled	(2.6		)
Revisions in Estimated Cash Flows	12.4
Obligation as of December 31, 2015	131.4
Accretion	8.0
Liabilities Settled	(6.5		)
Revisions in Estimated Cash Flows	3.7
Obligation as of December 31, 2016		$136.6

(a) The increase in 2015 is related to the ALLETE Clean Energy wind energy facilities acquisitions in 2015. (See Note 6. Acquisitions.)