Property, Plant And Equipment

3 Months Ended

Mar. 31, 2021

Property, Plant And Equipment [Abstract]

Property, Plant And Equipment

(6) Property, Plant and Equipment:

Property, plant and equipment, net is as follows:

($ in millions)	March 31, 2021		December 31, 2020
Property, plant and equipment	$	28,040	$	27,695
Less: Accumulated depreciation		(15,053)		(14,764)
Property, plant and equipment, net	$	12,987	$	12,931

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

	For the three months ended March 31,
($ in millions)	2021		2020
Depreciation expense	$	308	$	316

We revised the estimated remaining useful lives for certain plant assets as of October 1, 2020, 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.