Property, Plant And Equipment:

12 Months Ended

Dec. 31, 2015

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

PROPERTY, PLANT AND EQUIPMENT

Property, plant and equipment at December 31 consisted of the following (dollars in thousands):

Utilities Group	2015			2014			Lives (in years)
Electric Utilities	Property, Plant and Equipment		Weighted Average Useful Life (in years)	Property, Plant and Equipment		Weighted Average Useful Life (in years)	Minimum	Maximum
Electric plant:
Production	$	1,136,847	43	$	1,125,845	45	25	65
Electric transmission	301,280		52	284,032		49	40	70
Electric distribution	785,351		48	718,342		44	15	75
Plant acquisition adjustment (a)	4,870		32	4,870		32	32	32
General	180,840		24	152,982		21	3	65
Capital lease - plant in service (b)	261,441		20	261,441		20	20	20
Total electric plant in service	2,670,629			2,547,512
Construction work in progress	98,918			49,700
Total electric plant	2,769,547			2,597,212
Less accumulated depreciation and amortization	540,634			484,406
Electric plant net of accumulated depreciation and amortization	$	2,228,913		$	2,112,806

_____________

(a) The plant acquisition adjustment is included in rate base and is being recovered with 15 years remaining.

(b) Capital lease - plant in service represents the assets accounted for as a capital lease under the PPA between Colorado Electric and Black Hills Colorado IPP. The capital lease ends in conjunction with the expiration of the PPA on December 31, 2031.

	2015			2014			Lives (in years)
Gas Utilities	Property, Plant and Equipment		Weighted Average Useful Life (in years)	Property, Plant and Equipment		Weighted Average Useful Life (in years)	Minimum	Maximum
Gas plant:
Production	$	13	30	$	13	37	30	30
Gas transmission	24,081		62	24,090		54	53	70
Gas distribution	607,224		44	557,405		46	41	56
General	100,765		21	90,085		19	16	22
Total gas plant in service	732,083			671,593
Construction work in progress	9,437			16,072
Total gas plant	741,520			687,665
Less accumulated depreciation and amortization	106,778			92,035
Gas plant net of accumulated depreciation and amortization	$	634,742		$	595,630

2015											Lives (in years)
Non-regulated Energy	Property, Plant and Equipment		Construction Work in Progress		Total Property Plant and Equipment		Less Accumulated Depreciation, Depletion and Amortization		Net Property, Plant and Equipment		Weighted Average Useful Life	Minimum	Maximum
Power Generation	$	156,721	$	2,182	$	158,903	$	51,471	$	107,432	33	2	40
Coal Mining	154,630		3,649		158,279		97,663		60,616		13	2	59
Oil and Gas	1,132,776		—		1,132,776		925,908		206,868		24	3	25
	$	1,444,127	$	5,831	$	1,449,958	$	1,075,042	$	374,916

2014											Lives (in years)
Non-regulated Energy	Property, Plant and Equipment		Construction Work in Progress		Total Property Plant and Equipment		Less Accumulated Depreciation, Depletion and Amortization		Net Property, Plant and Equipment		Weighted Average Useful Life	Minimum	Maximum
Power Generation	$	153,779	$	2,262	$	156,041	$	47,704	$	108,337	33	2	40
Coal Mining	145,619		3,748		149,367		90,629		58,738		15	2	59
Oil and Gas	962,395		—		962,395		646,640		315,755		24	3	25
	$	1,261,793	$	6,010	$	1,267,803	$	784,973	$	482,830

2015												Lives (in years)
	Property, Plant and Equipment		Construction Work in Progress		Total Property Plant and Equipment		Less Accumulated Depreciation, Depletion and Amortization (a)			Net Property, Plant and Equipment		Weighted Average Useful Life	Minimum	Maximum
Corporate	$	376	$	15,377	$	15,753	$	(4,770	)	$	20,523	10	5	30

___________

(a) Accumulated depreciation, depletion and amortization at Corporate reflects the elimination of the capital lease accumulated depreciation difference between Colorado Electric and Black Hills Colorado IPP.

2014												Lives (in years)
	Property, Plant and Equipment		Construction Work in Progress		Total Property Plant and Equipment		Less Accumulated Depreciation, Depletion and Amortization (a)			Net Property, Plant and Equipment		Weighted Average Useful Life	Minimum	Maximum
Corporate	$	5,524	$	5,196	$	10,720	$	(3,485	)	$	14,205	11	5	30

___________

(a) Accumulated depreciation, depletion and amortization at Corporate reflects the elimination of the capital lease accumulated depreciation difference between Colorado Electric and Black Hills Colorado IPP.