Collaboration and Commercial Technology Licensing Agreements (Details) (Collaboration and specimen transfer agreements, USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Collaboration and Commercial Technology Licensing Agreements
Collaboration expense	$ 370,000	$ 451,000	$ 1,400,000	$ 2,200,000
Oncotype DX colon cancer test
Collaboration and Commercial Technology Licensing Agreements
Costs recorded under collaborative arrangements	2,000,000	2,900,000	6,000,000	7,800,000
Fixed future annual payments, exclusive of royalty payments
January 2013	450,000		450,000
January 2014	450,000		450,000
January 2015	450,000		450,000
Total	$ 1,350,000		$ 1,350,000