Restructuring and Asset Impairments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			12 Months Ended			6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2012	Dec. 31, 2012 Core Technologies	Dec. 31, 2012 2012 Restructuring Plan	Dec. 31, 2011 2011 Restructuring Plan	Dec. 31, 2012 2011 Restructuring Plan	Dec. 31, 2011 2011 Restructuring Plan	Dec. 31, 2011 2010 Restructuring Plan	Dec. 31, 2010 2010 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Total cost of restructuring						$ 19.2					$ 16.7
Employee separation and other costs related to one time employee termination benefits, after tax						13.0					11.4
Remaining liability related to restructuring charge						17.8
Cash payments related to restructuring charges						1.4
Severance costs							12.0
Severance costs after tax							8.1
Reversal of restructuring costs	1.6	1.1	1.1					1.8	1.6	2.6
Asset impairment charges related to core technologies associated with biopsy business, pre tax				22.2	13.2
Asset impairment charges related to core technologies associated with biopsy business, after tax				13.8	8.0
Asset impairment charges related to assets not related to operations, pre tax				9.0
Asset impairment charges related to assets not related to operations, after tax				$ 5.8