Property, Plant, and Equipment

6 Months Ended

Jun. 30, 2019

Property Plant And Equipment [Abstract]

Property, Plant, and Equipment

10. Property, Plant, and Equipment

The components of property, plant, and equipment were as follows (dollars in millions):

	June 30,			December 31,
	2019			2018
Land and land improvements	$	167.7		$	161.9
Buildings		812.0			795.5
Machinery and equipment		5,603.6			5,481.6
Construction in progress		172.2			176.7
Other		78.1			75.4
Property, plant and equipment, at cost		6,833.6			6,691.1
Less accumulated depreciation		(3,726.4	)		(3,582.5	)
Property, plant, and equipment, net	$	3,107.2		$	3,108.6

Depreciation expense for the three months ended June 30, 2019 and 2018 was $85.8 million and $91.6 million, respectively. During the six months ended June 30, 2019 and 2018, depreciation expense was $171.0 million and $186.2 million, respectively. We recognized $0.2 million and $13.5 million of incremental depreciation expense during the six months ended June 30, 2019 and 2018, respectively, as a result of shortening the useful lives of certain assets primarily related to the Wallula mill restructuring.

At June 30, 2019 and December 31, 2018, purchases of property, plant, and equipment included in accounts payable were $27.0 million and $24.7 million, respectively.