Collaborative Arrangements and Revenue Recognition - Summary of Revenues Disaggregated by Recognition at Point in Time and Over Time (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Point in Time
Disaggregation of Revenue [Line Items]
Revenues	$ 77	$ 2,529	$ 77	$ 3,495
Over Time
Disaggregation of Revenue [Line Items]
Revenues	0	1,664	0	2,139
Healios | Point in Time | License fee revenue
Disaggregation of Revenue [Line Items]
Revenues	0	1,624	0	1,624
Healios | Point in Time | Product supply revenue
Disaggregation of Revenue [Line Items]
Revenues	77	905	77	1,871
Healios | Point in Time | Service revenue
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Healios | Over Time | License fee revenue
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Healios | Over Time | Product supply revenue
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Healios | Over Time | Service revenue
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 1,664	$ 0	$ 2,139