Inventories (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Inventories
Raw materials	$ 156.5		$ 156.5		$ 158.8
Work-in-process	189.9		189.9		131.1
Finished goods	99.1		99.1		93.3
Demonstration units	37.6		37.6		38.8
Inventories	483.1		483.1		422.0
Inventory-in-transit	40.6		40.6		$ 44.7
Write-down of demonstration inventories to net realizable value	$ 4.0	$ 5.1	$ 12.5	$ 15.0