Property, Plant and Equipment

12 Months Ended

Dec. 31, 2015

Property, Plant and Equipment [Abstract]

The components of property, plant and equipment are as follows:



	December 31,
(in thousands)	2015		2014
Land	$	29,928	$	23,380
Land improvements and leasehold improvements	77,191		71,817
Buildings and storage facilities	303,482		275,059
Machinery and equipment	375,028		333,559
Construction in progress	32,871		29,620
	818,500		733,435
Less: accumulated depreciation	363,240		321,959
	$	455,260	$	411,476

Depreciation expense on property, plant and equipment amounted to $46.4 million, $40.5 million and

$36.4 million for the years ended 2015, 2014 and 2013, respectively.

In December 2013, the Company recorded losses totaling $4.4 million for asset impairment, primarily due to the write down of asset values in Retail. The Company wrote down the value of these assets to the extent their carrying amounts exceeded fair value. The Company classified the significant assumptions used to determine the fair value of the impaired assets, which was not material, as Level 3 inputs in the fair value hierarchy.

Rail Group Assets

The components of the Rail Group assets leased to others are as follows:



	December 31,
(in thousands)	2015		2014
Rail Group assets leased to others	$	434,051	$	384,958
Less: accumulated depreciation	95,940		87,211
	$	338,111	$	297,747

Depreciation expense on Rail Group assets leased to others amounted to $17.6 million, $14.2 million and $14.7 million for the years ended 2015, 2014 and 2013, respectively.