Inventories (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Inventories
Raw materials	$ 158.8	$ 159.5
Work-in-process	131.1	169.5
Finished goods	93.3	109.9
Demonstration units	38.8	38.5
Inventories	422.0	477.4
Inventory-in-transit	44.7	58.6
Write-down of demonstration inventories to net realizable value	$ 19.4	$ 28.2	$ 32.7