Properties, Plants and Equipment

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Properties, Plants and Equipment

Properties, Plants and Equipment

The components of properties, plants and equipment are as follows:

	December 31,
	2017			2016
	(In thousands)
Land, buildings and improvements	$	442,214		$	326,097
Refining facilities	3,904,161			3,382,369
Pipelines and terminals	1,484,502			1,392,898
Transportation vehicles	20,394			18,841
Other fixed assets	467,469			153,463
Construction in progress	205,049			273,188
	6,523,789			5,546,856
Accumulated depreciation	(1,810,515		)	(1,538,408		)
	$	4,713,274		$	4,008,448

During the year ended December 31, 2016, we recorded impairment charges of $309.3 million that are attributable to properties, plant and equipment of our Cheyenne reporting unit. See Note 10 for additional information.

We capitalized interest attributable to construction projects of $5.0 million, $8.0 million and $5.5 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Depreciation expense was $286.5 million, $247.9 million and $233.3 million for the years ended December 31, 2017, 2016 and 2015, respectively.