Leasehold Improvements, Equipment, Land and Construction in Progress, net

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Leasehold Improvements, Equipment, Land and Construction in Progress, net

Leasehold Improvements, Equipment, Land and Construction in Progress, net

Leasehold improvements, equipment, and construction in progress and related accumulated depreciation and amortization is as follows:

		December 31
(millions)	Ranges of Estimated Useful Life	2017			2016
Equipment	1 - 10 Years	$	39.6		$	38.6
Software	3 Years	31.9			30.9
Vehicles	1 - 10 Years	9.1			8.8
Other	3 Years	0.5			0.5
Leasehold improvements	Shorter of lease term or economic life up to 10 years	20.8			21.7
Construction in progress		2.7			3.3
		104.6			103.8
Less accumulated depreciation and amortization		(77.2		)	(72.9		)
Leasehold improvements, equipment, land and construction in progress, net		$	27.4		$	30.9

Asset additions are recorded at cost, which includes interest on significant projects. Depreciation is provided in amounts sufficient to relate the cost of depreciable assets to operations over their estimated useful lives or over the terms of the respective leases, whichever is shorter, and depreciated principally on the straight-line basis. The costs and accumulated depreciation of assets sold or disposed of are removed from the accounts and the resulting gain or loss is reflected in earnings. Plant and equipment are reviewed for impairment when conditions indicate an impairment or future impairment; the assets are either written down or the useful life is adjusted to the remaining period of estimated useful life.

The table below shows the Company's depreciation and amortization expense related to Leasehold improvements, equipment and construction in progress for the years ended December 31, 2017, 2016 and 2015, and is included in Depreciation and amortization expense within the Consolidated Statements of Income.

	Year Ended December 31,
(millions)	2017		2016		2015
Depreciation expense	$	11.3	$	16.2	$	15.9