Leasehold Improvements, Equipment, Land and Construction in Progress, net (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Summary of leasehold improvements, equipment, and construction in progress and related accumulated depreciation and amortization

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

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