Property, Plant and Equipment

6 Months Ended

Jun. 30, 2020

Property, Plant and Equipment [Abstract]

The components of Property, plant and equipment, net are as follows:


(in thousands)	June 30, 2020		December 31, 2019		June 30, 2019
Land	$	40,188	$	40,442	$	39,241
Land improvements and leasehold improvements	96,028		103,148		84,127
Buildings and storage facilities	377,652		373,961		327,418
Machinery and equipment	881,144		835,156		514,030
Construction in progress	35,982		59,993		164,532
	1,430,994		1,412,700		1,129,348
Less: accumulated depreciation	524,977		474,282		433,521
Property, plant and equipment, net	$	906,017	$	938,418	$	695,827

Depreciation expense on property, plant and equipment was $62.3 million and $32.7 million for the six months ended June 30, 2020 and 2019, respectively. Additionally, depreciation expense on property, plant and equipment was $31.2 million and $15.0 million for the three months ended June 30, 2020 and 2019, respectively.

In the second quarter of 2019, the Company recorded a $3.1 million impairment related to its remaining Tennessee facilities in the Trade group. The Company wrote down the assets to the extent their carrying values exceeded their fair value. The Company classified the significant assumptions used to determine the fair value of the impaired assets as Level 3 inputs in the fair value hierarchy.

Rail Group Assets

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


(in thousands)	June 30, 2020		December 31, 2019		June 30, 2019
Rail Group assets leased to others	$	742,107	$	723,004	$	688,320
Less: accumulated depreciation	149,286		138,706		128,609
Rail Group assets, net	$	592,821	$	584,298	$	559,711

Depreciation expense on Rail Group assets leased to others amounted to $15.4 million and $13.7 million for the six months ended June 30, 2020 and 2019, respectively. Additionally, depreciation expense on Rail Group assets leased to others amounted to $7.7 million and $7.0 million for the three months ended June 30, 2020 and 2019, respectively.