Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity (Details) - $ / shares	3 Months Ended	6 Months Ended
	Mar. 31, 2021	Jun. 30, 2021
Stock Option Plan of 2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding, Beginning balance	15,865,000	15,865,000
Number of RSUs Outstanding, Beginning balance	93,000	93,000
Weighted Average Exercise Price of Options Outstanding, beginning balance	$ 1.57	$ 1.57
Number of Options Outstanding, Restricted stock units vested
Number of RSUs Outstanding, Restricted stock units vested		(31,000)
Weighted Average Exercise Price of Options, Restricted stock units vested
Number of Options Outstanding, Options granted		5,120,000
Number of RSUs Outstanding, Options granted
Weighted Average Exercise Price of Options Outstanding, Options granted		$ 2.47
Number of Options Outstanding, Options exercised		(3,057,000)
Number of RSUs Outstanding, Options exercised
Weighted Average Exercise Price of Options, Options exercised		$ 1.89
Number of Options Outstanding, Options expired/forfeited/cancelled		(1,101,000)
Number of RSUs Outstanding, Options expired/forfeited/cancelled
Weighted Average Exercise Price of Options Outstanding, Options forfeited		$ 2.90
Number of Options Outstanding, Ending balance		16,827,000
Number of RSUs Outstanding, Ending balance		62,000
Weighted Average Exercise Price of Options Outstanding, Ending balance		$ 1.70
Number of Options Outstanding, Options exercisable		6,391,000
Weighted Average Exercise Price of Options Outstanding, Options exercisable		$ 1.74
Asterias 2013 Equity Incentive Plan [Member] | Asterias Biotherapeutics, Inc [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of RSUs Outstanding, Beginning balance	350,000	350,000
Weighted Average Exercise Price of Options Outstanding, beginning balance	$ 1.57	$ 1.57
Number of RSUs Outstanding, Options granted
Weighted Average Exercise Price of Options Outstanding, Options granted
Number of RSUs Outstanding, Ending balance		350,000
Weighted Average Exercise Price of Options Outstanding, Ending balance		$ 1,570
Weighted Average Exercise Price of Options Outstanding, Options exercisable		$ 1,570
Number of RSUs Outstanding, Ending balance		198,000