Property, Plant and Equipment, Net (Tables)

Property, plant and equipment, net consists of the following as of December 31 (in millions):



	Depreciable
	Life	2015			2014
Regulated assets:
Utility generation, transmission and distribution systems	5-80 years	$	69,248		$	64,645
Interstate natural gas pipeline assets	3-80 years	6,755			6,660
		76,003			71,305
Accumulated depreciation and amortization		(22,682		)	(21,447		)
Regulated assets, net		53,321			49,858

Nonregulated assets:
Independent power plants	5-30 years	4,751			4,362
Other assets	3-30 years	875			673
		5,626			5,035
Accumulated depreciation and amortization		(805		)	(839		)
Nonregulated assets, net		4,821			4,196

Net operating assets		58,142			54,054
Construction work-in-progress		2,627			5,194
Property, plant and equipment, net		$	60,769		$	59,248

Property, plant and equipment, net consists of the following as of December 31 (in millions):



	Depreciable Life	2015			2014

Utility plant in service:
Generation	20-100 years	$	10,404		$	9,351
Transmission	52-70 years	1,305			1,142
Electric distribution	20-70 years	3,059			2,933
Gas distribution	28-70 years	1,507			1,432
Utility plant in service		16,275			14,858
Accumulated depreciation and amortization		(5,229		)	(4,954		)
Utility plant in service, net		11,046			9,904
Nonregulated property, net:
Nonregulated property gross	5-45 years	15			14
Accumulated depreciation and amortization		(5		)	(5		)
Nonregulated property, net		10			9
		11,056			9,913
Construction work in progress		667			606
Property, plant and equipment, net		$	11,723		$	10,519

The average depreciation and amortization rates applied to depreciable utility plant for the years ended December 31 were as follows:

Property, plant and equipment, net consists of the following as of December 31 (in millions):



	Depreciable Life	2015			2014
Property, plant and equipment:
Generation	10 - 67 years	$	12,164		$	11,932
Transmission	58 - 75 years	5,914			5,392
Distribution	20 - 70 years	6,408			6,197
Intangible plant⁽¹⁾	5 - 62 years	875			879
Other	5 - 60 years	1,396			1,413
Property, plant and equipment in-service		26,757			25,813
Accumulated depreciation and amortization		(8,360		)	(8,026		)
Net property, plant and equipment in-service		18,397			17,787
Construction work-in-progress		629			932
Total property, plant and equipment, net		$	19,026		$	18,719


(1)	Computer software costs included in intangible plant are initially assigned a depreciable life of 5 to 10 years.

Property, plant and equipment, net consists of the following as of December 31 (in millions):



	Depreciable Life	2015			2014
Utility plant:
Generation	25 - 80 years	$	4,212		$	4,034
Distribution	20 - 65 years	3,118			3,018
Transmission	45 - 65 years	1,788			1,757
General and intangible plant	5 - 65 years	694			669
Utility plant		9,812			9,478
Accumulated depreciation and amortization		(2,971		)	(2,599		)
Utility plant, net		6,841			6,879
Other non-regulated, net of accumulated depreciation and amortization	5 - 65 years	2			4
Plant, net		6,843			6,883
Construction work-in-progress		153			120
Property, plant and equipment, net		$	6,996		$	7,003

Property, plant and equipment, net consists of the following as of December 31 (in millions):



	Depreciable Life	2015			2014
Utility plant:
Electric generation	40 - 125 years	$	1,134		$	1,036
Electric distribution	20 - 70 years	1,382			1,321
Electric transmission	50 - 70 years	739			719
Electric general and intangible plant	5 - 65 years	139			123
Natural gas distribution	40 - 70 years	374			366
Natural gas general and intangible plant	8 - 10 years	13			13
Common general	5 - 65 years	265			234
Utility plant		4,046			3,812
Accumulated depreciation and amortization		(1,368		)	(1,300		)
Utility plant, net		2,678			2,512
Construction work-in-progress		88			128
Property, plant and equipment, net		$	2,766		$	2,640