Property, Plant And Equipment

6 Months Ended

Jun. 30, 2017

Property, Plant And Equipment [Abstract]

Property, Plant And Equipment

(5)  Property, Plant and Equipment:

Property, plant and equipment, net is as follows:

($ in millions)	June 30, 2017		December 31, 2016
Property, plant and equipment	$	25,857	$	25,541
Less:  Accumulated depreciation		(11,375)		(10,639)
Property, plant and equipment, net	$	14,482	$	14,902

Depreciation expense is principally based on the composite group method. Depreciation expense was as follows:

	For the three months ended June 30,				For the six months ended June 30,
($ in millions)	2017		2016		2017		2016
Depreciation expense	$	379	$	446	$	755	$	686

We adopted new estimated remaining useful lives for certain plant assets as of October 1, 2016, as a result of an annual independent study of the estimated remaining useful lives of our plant assets, with an insignificant impact to depreciation expense.

In 2017, we sold and leased back certain properties, generating $86 million in net proceeds. We have deferred $59 million in gains, of which $26 million and $33 million are included in Other current liabilities and Other liabilities, respectively on our consolidated balance sheet as of June 30, 2017, and are being amortized over the related lease terms of 2 years.