Summary of Significant Accounting Policies - Additional Information (Detail)	0 Months Ended	3 Months Ended							12 Months Ended					1 Months Ended	3 Months Ended					12 Months Ended		0 Months Ended			12 Months Ended						12 Months Ended		0 Months Ended	12 Months Ended			0 Months Ended	12 Months Ended
	Apr. 06, 2007	Dec. 31, 2014 USD ($) Investment	Sep. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Sep. 30, 2013 USD ($)	Jun. 30, 2013 USD ($)	Mar. 31, 2013 USD ($)	Dec. 31, 2014 USD ($) Segment Investment	Dec. 31, 2013 USD ($)	Jan. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Jun. 02, 2014 USD ($)	Sep. 30, 2014 Technology Transfer USD ($)	Mar. 31, 2014 Technology Transfer USD ($)	Dec. 31, 2014 Technology Transfer USD ($)	Dec. 31, 2014 Non-Executive Employees	Dec. 31, 2014 Awards Granted to Executive Level Employees	Dec. 31, 2014 Non-employee members of Board of Directors	Dec. 31, 2014 Minimum	Dec. 31, 2014 Scripps Research Institute Licensing Agreements USD ($)	Dec. 28, 2014 Pfizer Incorporation Nonsoftware License Arrangement USD ($)	Sep. 04, 2013 Pfizer Incorporation Nonsoftware License Arrangement USD ($)	Jan. 22, 2013 Pfizer Incorporation Nonsoftware License Arrangement USD ($)	Dec. 31, 2014 Novozymes Biopharma DK A/S Sweden Ab Milestone Payments EUR (€)	Dec. 31, 2014 Bio Flash Minimum USD ($)	Dec. 31, 2014 Refine Technology, LLC USD ($)	Jun. 02, 2014 Refine Technology, LLC Milestone Payments USD ($)	Dec. 31, 2014 Significant unobservable inputs (Level 3) USD ($)	Dec. 31, 2014 Significant unobservable inputs (Level 3) Refine Technology, LLC USD ($)	Dec. 31, 2014 Clinical Development USD ($)	Dec. 31, 2014 Initial Commercial Sales USD ($)	Jan. 30, 2014 BioMarin Pharmaceutical, Inc. Asset Purchase Agreement USD ($)	Dec. 31, 2014 BioMarin Pharmaceutical, Inc. Asset Purchase Agreement USD ($)	Dec. 31, 2014 BioMarin Pharmaceutical, Inc. Clinical Development Asset Purchase Agreement	Dec. 31, 2014 BioMarin Pharmaceutical, Inc. Initial Commercial Sales Asset Purchase Agreement	Sep. 03, 2014 BioMarin Pharmaceutical, Inc. Technology Transfer Payments Asset Purchase Agreement USD ($)	Dec. 31, 2014 Orencia Royalties from Bristol USD ($)	Dec. 31, 2013 Orencia Royalties from Bristol USD ($)	Dec. 31, 2012 Orencia Royalties from Bristol USD ($)
Summary Of Significant Accounting Policies [Line Items]
License Agreement, initial license fee																					$ 300,000
Total future milestone payments																					4,300,000
Common stock, shares issued																					87,464
Common stock, shares issued value																					300,000
Common stock, shares purchased through issuance of warrants	150,000																				150,000
Warrant term	7 years																				7 years
Upfront payment received under license agreement																								5,000,000									2,000,000
Milestone payment																						1,000,000	1,000,000								60,000,000						125,675
Potential milestone payments to be received																															60,000,000	100,000,000		160,000,000
Percentage relate to clinical development from Milestone payment																																			37.00%	63.00%
Provision for refund																																		0
License agreement, revenue recognized									2,115,000						0																			2,100,000
Non-refundable up-front payment									2,000,000
Payment to be received upon signing of agreement									125,675
Revenue recognized under revenue recognition, up front payment				2,000,000
Estimated selling price																300,000
Consideration allocated to transaction																11,000
Royalty and other revenue		1,000,000	125,000	1,991,000	5,032,000	6,638,000	4,495,000	4,522,000	3,116,841	20,687,241		20,432,348		125,675																								0	17,881,000	14,753,000
Royalty term																															10 years
Percentage of royalty revenue, remittance to the University of Michigan									15.00%
Cost of royalty revenue					738,000	724,000	643,000	577,000		2,682,177		2,213,004																										0	2,682,000	2,213,000
Revenue from sponsored research and development projects									0	1,589,000		803,000
Marketable securities, minimum original maturity term																				90 days
Long-term marketable securities, minimum original maturity term									1 year
Marketable securities, average remaining contractual maturity period									7 years 8 months 12 days
Number of debt securities in unrealized loss positions		41							41
Debt securities in unrealized loss positions, total unrealized loss		9,400							9,400
Debt securities in unrealized loss positions, total fair market value		23,666,285							23,666,285
Credit risk		0							0
Gain (loss) on investments									0	0	0
Fair value of other assets		0							0
Payment made									1,246,348																850,000
Royalty payment																										80,000
Additional contingent consideration accrued													1,370,000														1,370,000	1,370,000	3,321,000	3,321,000
Reserves for excess and obsolete inventory		78,000			183,000				78,000	183,000
Depreciation expense of property and equipment									2,594,000	2,092,000		2,492,000
Stock options, outstanding		1,225,117			1,610,988				1,225,117	1,610,988		2,315,090
Stock options, weighted average exercise price		$ 8.31			$ 5.07				$ 8.31	$ 5.07		$ 4.20
Common stock excluded from calculation of diluted earnings per share									307,475	187,000		1,296,700
Number of operating segment									1
Goodwill impairment									0	0		0
Amortization expense									1,425,000	1,022,000		1,017,000
Expected dividend yield									$ 0
Estimated forfeiture rates																	8.00%	3.00%	0.00%