Acquisitions (Details) (SkyScan N.V., USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012
Consideration Transferred:
Cash paid	$ 24.6
Cash acquired	(2.9)
Contingent consideration	4.0
Total consideration transferred	25.7
Allocation of Consideration Transferred:
Accounts receivable	3.1
Inventories	6.6
Other current assets	0.3
Property, plant and equipment	2.3
Goodwill	10.6
Liabilities assumed	(10.8)
Total consideration transferred	25.7
Maximum
Allocation of Consideration Transferred:
Contingent consideration arrangement	5.9
Existing technology
Allocation of Consideration Transferred:
Intangible assets	7.2
Weighted average amortization period	7 years
Customer relationships
Allocation of Consideration Transferred:
Intangible assets	$ 6.4
Weighted average amortization period	10 years