Property, Plant and Equipment

12 Months Ended

Dec. 31, 2015

Property, Plant and Equipment [Abstract]

The following is a summary of property, plant and equipment, at cost less accumulated depreciation and amortization as of December 31:



	Estimated Useful Life (years)	2015		2014
Land and land improvements	0-15	$	6.1	$	7.0
Buildings and building equipment	15	57.7		59.5
Machinery, tools and equipment	5-12	83.5		86.0
Leasehold improvements ⁽¹⁾	10	22.1		24.1
Computer equipment	3-5	58.4		56.6
Computer software	5-10	188.4		160.2
Furniture and fixtures	5-8	62.0		63.6
Tooling	3-5	104.5		94.6
Construction in progress		26.3		53.2
Total property plant and equipment, at cost		$	609.0	$	604.8
Less accumulated depreciation and amortization		433.7		439.1
Total property plant and equipment, net		$	175.3	$	165.7


⁽¹⁾	The estimated useful life for leasehold improvements is the lesser of 10 years or the term of the lease.

During 2015, 2014 and 2013, depreciation expense, computed on a straight-line basis over the estimated useful lives of the related assets, was $40.7, $48.2 and $50.2, respectively.