Commitments and Contingencies - Additional Information (Detail)					1 Months Ended			12 Months Ended
	Apr. 21, 2017 USD ($) ft²	Sep. 30, 2016 USD ($) ft²	Apr. 18, 2016 USD ($) ft²	Mar. 11, 2015 USD ($)	Sep. 30, 2016 USD ($) ft²	Sep. 30, 2013 USD ($)	Jul. 31, 2013	Dec. 31, 2017 USD ($) $ / ft²	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jun. 30, 2014 USD ($) ft²	Dec. 31, 2013 ft²
Long-term Purchase Commitment [Line Items]
Period of supply agreement							5 years
Supply agreement amended date								2017-04
Minimum remaining purchase commitment								$ 11,743,000
Bluebird [Member]
Long-term Purchase Commitment [Line Items]
Lease agreement effective date								May 01, 2017
ARE Lease [Member] | ARE-7030 Kit Creek, LLC [Member]
Long-term Purchase Commitment [Line Items]
Area of office and laboratory space under lease agreement | ft²			48,236
Lease rent abatement period								9 months
Lease expiration date								Jan. 31, 2022
Extendable/extended lease term								10 years
Rent expense associated with the lease								$ 923,000	$ 675,000
Lease rent per month			$ 86,423
Lease agreement start date								Apr. 18, 2016
Increase in annual lease rent, percentage			3.00%
ARE Lease [Member] | ARE-7030 Kit Creek, LLC [Member] | Maximum [Member]
Long-term Purchase Commitment [Line Items]
Tenant improvements to leased space			$ 1,205,900
Penzberg, Germany Lease [Member] | Roche Diagnostics, GmbH [Member]
Long-term Purchase Commitment [Line Items]
Lease expiration date								Sep. 08, 2021
Extendable/extended lease term								2 years
Lease agreement start date								Sep. 09, 2016
150 Second Street [Member]
Long-term Purchase Commitment [Line Items]
Area of office and laboratory space under lease agreement | ft²														61,591
Lease expected term								8 years
Lease rent waiver period								10 months 15 days
Value of rent obligations						$ 3,300,000
Security deposit of lease agreement						1,725,000						$ 864,000
Tenant improvements						$ 9,239,000
Rent expense associated with the lease								$ 5,983,000	2,534,000	$ 2,534,000
150 Second Street [Member] | Second Amendment [Member]
Long-term Purchase Commitment [Line Items]
Tenant improvements													$ 1,020,500
Additional space for lease | ft²													8,164
Lease commencement date								2014-11
150 Second Street [Member] | Third Amendment [Member]
Long-term Purchase Commitment [Line Items]
Area of office and laboratory space under lease agreement | ft²		123,210			123,210
Security deposit of lease agreement								$ 1,771,009
Tenant improvements to leased space		$ 2,500,000
Lease rent abatement period								2 months
Lease expiration date								Apr. 30, 2024
Extendable/extended lease term								5 years
150 Second Street [Member] | Third Amendment [Member] | Minimum [Member]
Long-term Purchase Commitment [Line Items]
Annual base rent payable per square foot | $ / ft²								70.51
150 Second Street [Member] | Third Amendment [Member] | Maximum [Member]
Long-term Purchase Commitment [Line Items]
Annual base rent payable per square foot | $ / ft²								83.42
150 Second Street [Member] | Third Amendment [Member] | Bluebird [Member]
Long-term Purchase Commitment [Line Items]
Area of office and laboratory space surrendered under lease agreement | ft²		53,455			53,455
150 Second Street [Member] | Bluebird Premises [Member] | Minimum [Member]
Long-term Purchase Commitment [Line Items]
Annual base rent payable per square foot | $ / ft²								62.83
150 Second Street [Member] | Bluebird Premises [Member] | Maximum [Member]
Long-term Purchase Commitment [Line Items]
Annual base rent payable per square foot | $ / ft²								72.84
One Kendall Square [Member]
Long-term Purchase Commitment [Line Items]
Lease expected term								7 years 6 months
Rent abatement								$ 1,841,000
Ten Canal Park Lease [Member]
Long-term Purchase Commitment [Line Items]
Security deposit of lease agreement				$ 1,037,000							$ 530,550
Tenant improvements to leased space				1,995,550
Lease expiration date								Aug. 31, 2020
Rent expense associated with the lease								$ 1,630,000	1,630,000	$ 1,279,000
Lease rent per month				$ 172,850
525 University Avenue [Member] | Second Amendment [Member] | PAOC [Member]
Long-term Purchase Commitment [Line Items]
Area of office and laboratory space under lease agreement | ft²	1,975
Lease expiration date								Apr. 30, 2022
Extendable/extended lease term								60 months
Rent expense associated with the lease								$ 220,000
Lease rent per month	$ 17,775
Increase in annual lease rent, percentage	3.00%
Lease rent abatement period								2017-05
Penzberg, Germany Lease [Member] | Roche Diagnostics, GmbH [Member]
Long-term Purchase Commitment [Line Items]
Rent expense associated with the lease								$ 286,000	$ 79,000
Lease rent per month					$ 22,000
Increase in annual lease rent, percentage		2.00%