Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2015

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

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

				2015				2014
				Weighted				Weighted
				Average				Average	Lives (in years)
	2015			Useful Life (in years)	2014			Useful Life (in years)	Minimum	Maximum
Electric plant:
Production	$	569,182		46	$	567,936		48	40	65
Transmission	117,708			48	115,949			46	40	60
Distribution	353,241			46	336,652			39	20	60
Plant acquisition adjustment (a)	4,870			32	4,870			32	32	32
General	88,939			22	79,738			22	5	40
Total plant-in-service	1,133,940				1,105,145
Construction work in progress	32,186				9,916
Total electric plant	1,166,126				1,115,061
Less accumulated depreciation and amortization	(326,074		)		(309,767		)
Electric plant net of accumulated depreciation and amortization	$	840,052			$	805,294

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