Property, Plant and Equipment

9 Months Ended

Sep. 30, 2016

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

6.  PROPERTY, PLANT AND EQUIPMENT

A summary of the historical cost of property, plant and equipment is as follows:

thousands	Estimated Useful Life	September 30, 2016		December 31, 2015
Land	n/a	$	4,000	$	3,744
Gathering systems	3 to 47 years	6,471,338		6,061,004
Pipelines and equipment	15 to 45 years	135,504		136,290
Assets under construction	n/a	272,169		329,887
Other	3 to 40 years	29,895		25,853
Total property, plant and equipment		6,912,906		6,556,778
Accumulated depreciation		1,882,012		1,697,999
Net property, plant and equipment		$	5,030,894	$	4,858,779

The cost of property classified as “Assets under construction” is excluded from capitalized costs being depreciated. These amounts represent property that is not yet suitable to be placed into productive service as of the respective balance sheet date.

As of September 30, 2016, net property, plant and equipment includes impairments of $11.3 million, including an impairment of $6.1 million at WES’s Newcastle system. This asset was impaired to its estimated fair value of $3.1 million, using the income approach and Level 3 fair value inputs, due to a reduction in estimated future cash flows caused by the low commodity price environment. Also during this period, WES recognized impairments of $5.2 million, primarily related to the abandonment of compressors at the MIGC system and cancellation of projects at the DBJV and Anadarko-Operated Marcellus Interest systems. See Note 2 for a discussion of WES’s assets held for sale as of September 30, 2016.