Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended
	Mar. 31, 2014 sqft	Mar. 31, 2014 sqft
Commitments and Contingencies [Line Items]
Area of office and laboratory space held under operating lease	129,000	129,000
Lease expiration date		2016-09
Lease extension period	5 years
Lease extended expiration date	Sep. 30, 2021
First Amendment
Commitments and Contingencies [Line Items]
Lease amendment date		Mar. 16, 2006
Second Amendment
Commitments and Contingencies [Line Items]
Lease amendment date		Jun. 26, 2009
Third Amendment
Commitments and Contingencies [Line Items]
Lease amendment date		May 11, 2010
Fourth Amendment
Commitments and Contingencies [Line Items]
Lease amendment date		Nov. 04, 2011
Fifth Amendment
Commitments and Contingencies [Line Items]
Lease extension period	5 years
Operating lease obligation through 2021	$ 37.8	$ 37.8