Collaboration and Commercial Technology Licensing Agreements (Details) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Jul. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2015
Specimen transfer agreements
Collaboration payments and costs
Collaboration expense			$ 11,100,000	$ 6,400,000	$ 12,600,000
Oncotype DX DCIS score agreement
Fixed annual payments
2016			604,000
2017			504,000
Exclusive license agreement
Collaboration payments and costs
Estimated total remaining obligation, including milestone payments			0
Exclusive license agreement | Research and development expense.
Collaboration payments and costs
Up-front payment		$ 9,000,000
Agreement break-up fee maximum						$ 5,500,000
Technology license agreements | Cost of product revenues
Collaboration payments and costs
Costs recorded under collaborative arrangements			9,200,000	$ 9,500,000	$ 8,900,000
Oncotype DX Prostate Cancer GPS
Collaboration payments and costs
Estimated total remaining obligation, including milestone payments			$ 3,000,000
Oncotype DX Prostate Cancer GPS | Minimum
Collaboration payments and costs
Number of years of active surveillance	1 year
Oncotype DX Prostate Cancer GPS | Maximum
Collaboration payments and costs
Number of years of active surveillance	2 years