Collaborative Research, Development, and License Agreements - Additional Information (Detail) (USD $)
 12 Months Ended 1 Months Ended 3 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 3 Months Ended 12 Months Ended 1 Months Ended
Dec. 31, 2011
Dec. 31, 2008
Glaxo, Smith, Kline
Project
Dec. 31, 2013
Glaxo, Smith, Kline
Dec. 31, 2013
Glaxo, Smith, Kline
Dec. 31, 2012
Glaxo, Smith, Kline
Dec. 31, 2011
Glaxo, Smith, Kline
Dec. 31, 2011
Glaxo, Smith, Kline
Expansion
Dec. 31, 2013
Glaxo, Smith, Kline
Maximum
Dec. 31, 2013
Glaxo, Smith, Kline
Maximum
Annual net sales milestones achieved
Dec. 31, 2013
Glaxo, Smith, Kline
Minimum
Sep. 30, 2006
Astra Zeneca
Dec. 31, 2013
Astra Zeneca
Dec. 31, 2012
Astra Zeneca
Dec. 31, 2011
Astra Zeneca
Oct. 31, 2011
Amendment
Dec. 31, 2011
Amendment
Dec. 31, 2012
Amendment
Advance the program following completion of Phase 2a
Mar. 31, 2012
Amendment
Advance the program following completion of Phase 2a
Dec. 31, 2013
Amendment
Advance the program following completion of Phase 2a
Dec. 31, 2013
Amendment
Maximum
Advance the program following completion of Phase 2a
Sep. 30, 2013
Hepatic Fibrosis and Cirrhosis
National Institutes of Health
Jun. 30, 2012
Autoimmune Disease
National Institutes of Health
May 31, 2012
Rheumatoid Arthritis
National Institutes of Health
Jul. 31, 2011
Skin Autoimmune Inflammation
National Institutes of Health
Aug. 31, 2010
HBV
National Institutes of Health
Jul. 31, 2010
HPV
National Institutes of Health
Sep. 30, 2008
ISS Technology
National Institutes of Health
Product Information [Line Items]                                                      
Number of programs for research and early clinical development   4                                                  
Potential milestone payment               $ 125,000,000 $ 60,000,000                                    
Collaboration Revenue   10,000,000   1,702,000 1,428,000 1,428,000           720,000 720,000 120,000 3,000,000   6,000,000 2,600,000                  
Revenue from milestone payment 12,000,000         15,000,000 3,000,000         2,507,000 2,462,000 642,000         20,000,000 100,000,000              
Deferred revenue recognition period               7 years   6 years   50 months                              
Additional revenue recognized     300,000                                                
Deferred revenue     2,500,000 2,500,000 4,200,000             4,800,000 7,700,000                            
Research collaboration and license agreement period                     3 years                                
Cost of clinical development activities                               20,000,000                      
Grants receivable                                         200,000 600,000 400,000 600,000 1,400,000 600,000  
Contract agreement period                                                     5 years
Contract awarded to develop technology                                                     $ 17,000,000