Property, Plant, and Equipment

12 Months Ended

Dec. 31, 2015

Property, Plant and Equipment [Abstract]

Property, Plant, and Equipment

PROPERTY, PLANT, AND EQUIPMENT

The following is a summary of Property, plant, and equipment by classification as of December 31:

	2015			2014
Property, plant, and equipment	(In millions)
DTE Electric
Generation	$	11,767		$	10,712
Distribution	7,816			7,414
Other	1,808			1,679
Total DTE Electric	21,391			19,805
DTE Gas
Distribution	3,124			2,946
Storage	453			448
Transmission and other	890			863
Total DTE Gas	4,467			4,257
Non-utility and other	2,263			2,476
Total DTE Energy	28,121			26,538
Less accumulated depreciation and amortization
DTE Electric
Generation	(4,346		)	(3,863		)
Distribution	(2,707		)	(2,822		)
Other	(593		)	(531		)
Total DTE Electric	(7,646		)	(7,216		)
DTE Gas
Distribution	(1,163		)	(1,130		)
Storage	(147		)	(142		)
Transmission and other	(370		)	(363		)
Total DTE Gas	(1,680		)	(1,635		)
Non-utility and other	(761		)	(867		)
Total DTE Energy	(10,087		)	(9,718		)
Net DTE Energy Property, plant, and equipment	$	18,034		$	16,820
Net DTE Electric Property, plant, and equipment	$	13,745		$	12,589

AFUDC and interest capitalized was approximately $34 million and $37 million for DTE Energy for the years ended December 31, 2015 and 2014, respectively, including AFUDC capitalized of approximately $31 million and $32 million for DTE Electric for the years ended December 31, 2015 and 2014, respectively.

The composite depreciation rate for DTE Electric was approximately 3.5% in 2015 and 3.4% in 2014 and 2013. The composite depreciation rate for DTE Gas was 2.6% in 2015 and 2.4% in 2014 and 2013. The average estimated useful life for each major class of utility Property, plant, and equipment as of December 31, 2015 follows:

	Estimated Useful Lives in Years
Utility	Generation	Distribution	Storage
DTE Electric	40	41	N/A
DTE Gas	N/A	50	53

The estimated useful lives for DTE Electric's Other utility assets range from 5 to 62 years, while the estimated useful lives for DTE Gas' Transmission and other utility assets range from 5 to 70 years. The estimated useful lives for major classes of DTE Energy's non-utility assets and facilities range from 3 to 55 years.

The following is a summary of Depreciation and amortization expense for DTE Energy, including DTE Electric:

	2015			2014		2013
	(In millions)
Property, plant, and equipment	$	740		$	683	$	630
Regulatory assets and liabilities	150			159		163
Securitized regulatory assets (a)	(38		)	303		301
	$	852		$	1,145	$	1,094

The following is a summary of Depreciation and amortization expense for DTE Electric:

	2015			2014		2013
	(In millions)
Property, plant, and equipment	$	545		$	489	$	457
Regulatory assets and liabilities	126			135		138
Securitized regulatory assets (a)	(38		)	303		301
	$	633		$	927	$	896

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(a) Securitization surcharges ended in December 2014 with remaining over recovery refunded to customers in 2015. Securitization bonds were paid and Securitization regulatory assets amortization was completed in 2015. The $38 million credit represents the final adjustments to close out the Securitization program.

Capitalized software costs are classified as Property, plant, and equipment and the related amortization is included in accumulated depreciation and amortization on the Registrants' Consolidated Financial Statements. The Registrants capitalize the costs associated with computer software developed or obtained for use in their businesses. The Registrants amortize capitalized software costs on a straight-line basis over the expected period of benefit, ranging from 3 to 15 years for DTE Energy and 5 to 15 years for DTE Electric. The following balances for capitalized software relate to DTE Energy, including DTE Electric:

	Year Ended December 31,
	2015		2014		2013
	(In millions)
Amortization expense of capitalized software	$	98	$	77	$	71
Gross carrying value of capitalized software	$	770	$	668
Accumulated amortization of capitalized software	$	439	$	335

The following balances for capitalized software relate to DTE Electric:

	Year Ended December 31,
	2015		2014		2013
	(In millions)
Amortization expense of capitalized software	$	80	$	71	$	64
Gross carrying value of capitalized software	$	664	$	590
Accumulated amortization of capitalized software	$	369	$	293

Property under capital leases for the Registrants is as follows:

	DTE Energy				DTE Electric
	2015		2014		2015		2014
	(In millions)
Gross property under capital leases	$	48	$	35	$	22	$	9
Accumulated amortization of property under capital leases	$	26	$	27	$	1	$	5