Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2015

Property, Plant and Equipment [Abstract]

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

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

Property, Plant and Equipment
As of December 31	2015			2014
Millions
Regulated Operations		$4,336.7			$3,903.3
Construction Work in Progress	101.2			355.4
Accumulated Depreciation	(1,323.8		)	(1,260.2		)
Regulated Operations – Net	3,114.1			2,998.5
ALLETE Clean Energy	467.3			203.7
Construction Work in Progress	4.0			1.3
Accumulated Depreciation	(24.0		)	(8.4		)
ALLETE Clean Energy – Net	447.3			196.6
U.S. Water Services	15.6			—
Accumulated Depreciation	(3.4		)	—
U.S. Water Services – Net	12.2			—
Corporate and Other (a)	165.6			152.5
Construction Work in Progress	4.5			4.6
Accumulated Depreciation	(74.6		)	(67.4		)
Corporate and Other – Net	95.5			89.7
Property, Plant and Equipment – Net		$3,669.1			$3,284.8

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

Asset Retirement Obligations [Table Text Block]

Asset Retirement Obligations
Millions
Obligation as of December 31, 2013		$81.8
Accretion	5.5
Liabilities Recognized (a)	23.0
Liabilities Settled	(0.5		)
Revisions in Estimated Cash Flows	(0.6		)
Obligation as of December 31, 2014	109.2
Accretion	7.3
Liabilities Recognized (b)	5.1
Liabilities Settled	(2.6		)
Revisions in Estimated Cash Flows	12.4
Obligation as of December 31, 2015		$131.4

(a) The increase in 2014 is related to BNI Energy for coal mining expansion and ALLETE Clean Energy due to wind energy facilities acquisitions.(See Note 7. Acquisitions.)

(b) The increase in 2015 is related to the ALLETE Clean Energy wind energy facilities acquisitions in 2015. (See Note 7. Acquisitions.)