Leases - Additional Information (Details)			12 Months Ended
	Oct. 15, 2019 USD ($) ft²	Mar. 12, 2019 USD ($) ft²	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($)	Jan. 30, 2018 USD ($) ft²
Land Subject to Ground Leases | ft²		1,038
Lessee Operating Lease Monthly Average Rental Payment		$ 2,000
Operating Lease, Payments			$ 700,000
Total rent expense				$ 700,000	$ 700,000
Operating Lease, Right-of-Use Asset			2,272,000
Operating Lease, Liability			2,352,000
Recognisition in exchange of Operating Lease Liabilities			1,200,000
Boston, MA
Security Deposit			$ 100,000	$ 100,000
Sublease term amendment			Aug. 31, 2021
Operating lease expiration month and year			2016-08
Houston, TX
Land Subject to Ground Leases | ft²	8,443
Operating Lease Area | ft²							210
Operating Leases Future Minimum Monthly Payment Due Through Year 2021	$ 17,000						$ 1,000
Annual Base Rent	3.00%
Adjustments for New Accounting Pronouncement [Member]
Operating Lease, Right-of-Use Asset						$ 1,600,000
Operating Lease, Liability						$ 1,600,000