Cyclerion Separation - Separation Agreement (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Apr. 01, 2019
Assets:
Prepaid expenses and other current assets	$ 10,443	$ 10,685
Property and equipment, net	12,164	12,429
Other assets	838	790
Total assets	404,005	402,748
Liabilities:
Accrued research and development costs	2,286	2,956
Accrued expenses and other current liabilities	$ 18,719	$ 30,465
Cyclerion Therapeutics, Inc.
Assets:
Prepaid expenses and other current assets			$ 1,169
Property and equipment, net			10,241
Other assets			21
Total assets			11,431
Liabilities:
Accrued research and development costs			5,673
Accrued expenses and other current liabilities			3,149
Total liabilities			8,822
Net Assets Transferred to Cyclerion			$ 2,609