PROPERTY, PLANT AND EQUIPMENT

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT

		December 31,
	Useful Lives	2017			2016
		($ in millions)
Land and improvements to land	10-20 Years	$	281.7		$	281.2
Buildings and building equipment	10-30 Years	382.4			375.0
Machinery and equipment	3-15 Years	5,028.4			4,765.9
Leasehold improvements		3.9			3.4
Construction in progress		212.5			171.0
Property, plant and equipment		5,908.9			5,596.5
Accumulated depreciation		(2,333.1		)	(1,891.6		)
Property, plant and equipment, net		$	3,575.8		$	3,704.9

The weighted-average useful life of machinery and equipment at December 31, 2017 was 12 years. Depreciation expense was $465.1 million, $435.7 million and $198.1 million for 2017, 2016 and 2015, respectively.  Interest capitalized was $3.0 million, $1.9 million and $1.1 million for 2017, 2016 and 2015, respectively.  Maintenance, turnaround costs and repairs charged to operations amounted to $414.7 million, $329.6 million and $187.7 million in 2017, 2016 and 2015, respectively.

The consolidated statements of cash flows for the years ended December 31, 2017, 2016 and 2015, included an increase of $0.5 million and decreases of $29.9 million and $7.4 million, respectively, to capital expenditures, with the corresponding change to accounts payable and accrued liabilities, related to purchases of property, plant and equipment included in accounts payable at December 31, 2017, 2016 and 2015.

During 2016, we entered into sale/leaseback transactions for railcars that we acquired in connection with the Acquisition. We received proceeds from the sales of $40.4 million for the year ended December 31, 2016.