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Property, Plant And Equipment
9 Months Ended
Sep. 30, 2014
Property, Plant And Equipment [Abstract]  
Property, Plant And Equipment

(5)   Property, Plant and Equipment:

Property, plant and equipment, net is as follows:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

($ in thousands)

 

September 30, 2014

 

December 31, 2013

    

 

 

 

 

 

 

Property, plant and equipment

 

15,311,984 

 

$

14,850,697 

Less:  Accumulated depreciation

 

 

(8,159,523)

 

 

(7,594,935)

Property, plant and equipment, net

 

$

7,152,461 

 

$

7,255,762 

 

Depreciation expense is principally based on the composite group method. Depreciation expense was $195.0 million and $208.7 million, and $598.1 million and $636.2 million, for the three  and nine months ended September 30, 2014 and 2013, respectively. As a result of our annual independent study of the estimated remaining useful lives of our plant assets, we adopted new estimated remaining useful lives for certain plant assets as of October 1, 2013, with an insignificant impact to depreciation expense.