Property, Plant and Equipment

3 Months Ended

Mar. 31, 2018

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

7. PROPERTY, PLANT AND EQUIPMENT

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

thousands	Estimated Useful Life	March 31, 2018		December 31, 2017
Land	n/a	$	4,449	$	4,450
Gathering systems and processing complexes	3 to 47 years	7,305,279		7,114,701
Pipelines and equipment	15 to 45 years	137,765		137,644
Assets under construction	n/a	794,012		577,914
Other	3 to 40 years	30,578		36,393
Total property, plant and equipment		8,272,083		7,871,102
Accumulated depreciation		2,208,536		2,140,211
Net property, plant and equipment		$	6,063,547	$	5,730,891

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.

Impairments. During the three months ended March 31, 2018, WES recognized impairments of $0.1 million.

During the year ended December 31, 2017, WES recognized impairments of $178.4 million, including an impairment of $158.8 million at the Granger complex, which was impaired to its estimated fair value of $48.5 million using the income approach and Level 3 fair value inputs, due to a reduced throughput fee as a result of a producer’s bankruptcy. The remaining $19.6 million of impairments was primarily related to (i) an $8.2 million impairment due to the cancellation of a plant project at the Hilight system, (ii) a $3.7 million impairment at the Granger straddle plant, which was impaired to its estimated salvage value of $0.6 million using the income approach and Level 3 fair value inputs, (iii) a $3.1 million impairment of the Fort Union equity investment, (iv) a $2.0 million impairment of an idle facility in northeast Wyoming, which was impaired to its estimated salvage value of $0.4 million using the market approach and Level 3 fair value inputs, and (v) the cancellation of a pipeline project in West Texas.