Build-to-Suit Lease Obligation - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015 sqft	Dec. 31, 2013 sqft	Dec. 31, 2014
Build To Suit Lease Obligation [Line Items]
Build to suit lease	143,000
Interest capitalized during construction period for build-to-suit lease transactions	$ 527,000
Build-to-suit lease obligation current liability	469,000		698,000
Build-to-suit lease obligation non-current liability	19,240,000		18,711,000
Laboratory Space [Member]
Build To Suit Lease Obligation [Line Items]
Build to suit lease		52,000
Lease expiry period	July 2024
Build to suit lease extension term		5 years
Build-to-suit Lease Property and Equipment [Member]
Build To Suit Lease Obligation [Line Items]
Amounts capitalized under build-to-suit transactions	14,500,000
Tenant Improvements [Member]
Build To Suit Lease Obligation [Line Items]
Amounts capitalized under build-to-suit transactions	$ 3,600,000