Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended				12 Months Ended	2 Months Ended	12 Months Ended		1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jan. 31, 2013 Manufacturing of subunits	Dec. 31, 2012 Cambridge, Massachusetts	Feb. 28, 2013 Cambridge, Massachusetts Subsequent Event	Dec. 31, 2012 Corvallis, Oregon	Dec. 31, 2012 Corvallis, Oregon land lease	May 31, 2012 Bothell, Washington
Commitment And Contingencies [Line Items]
Lease agreement, monthly service fee					$ 33,000	$ 7,700
Lease expiration date					Jun. 30, 2013				May 31, 2013
Lease agreement, expiration period						12 months
Monthly rent							72,000	700	46,000
Percentage of annual increase in lease							3.00%	1.50%
One-time termination fee									210,000
Rent expenses under leases	2,552,000	2,498,000	1,821,000
Notice period to terminate license agreements	6 months
Royalty payments	141,000	94,000	100,000
Maximum royalty to Charley's Fund	3,400,000
Purchase commitments	$ 2,095,000			$ 20,800,000