Stock-Based Awards - Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity (Details) - $ / shares	4 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Stock Option Plan of 2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Available for Grant, Beginning balance		1,885,000
Shares Available for Grant, AgeX distribution adjustment		117,000
Shares Available for Grant, Restricted stock units vested
Shares Available for Grant, Options granted		(2,337,000)
Shares Available for Grant, Options exercised
Shares Available for Grant, Options expired/ forfeited/cancelled		1,264,000
Shares Available for Grant, Ending balance	929,000	929,000
Number of Options Outstanding, Beginning balance		13,867,000
Number of Options Outstanding, AgeX distribution adjustment		(2,000)
Number of Options Outstanding, Restricted stock units vested
Number of Options Outstanding, Options granted		2,337,000
Number of Options Outstanding, Options exercised
Number of Options Outstanding, Options expired/forfeited/cancelled		(1,264,000)
Number of Options Outstanding, Ending balance	14,938,000	14,938,000
Number of Options Outstanding, Options exercisable	9,213,000	9,213,000
Number of RSUs Outstanding, Beginning balance		402,000
Number of RSUs Outstanding, AgeX distribution adjustment		3,000
Number of RSUs Outstanding, Restricted stock units vested		(135,000)
Number of RSUs Outstanding, Options granted
Number of RSUs Outstanding, Options exercised
Number of RSUs Outstanding, Options expired/forfeited/cancelled
Number of RSUs Outstanding, Ending balance	270,000	270,000
Weighted Average Exercise Price of Options Outstanding, beginning balance		$ 2.44
Weighted Average Exercise Price of Options, AgeX distribution adjustment
Weighted Average Exercise Price of Options, Restricted stock units vested
Weighted Average Exercise Price of Options, Options granted		1.14
Weighted Average Exercise Price of Options, Options exercised
Weighted Average Exercise Price of Options, Options expired/forfeited/cancelled		2.09
Weighted Average Exercise Price of Options, Outstanding end balance	$ 2.27	2.27
Weighted Average Exercise Price of Options, Options exercisable	$ 2.59	$ 2.59
Asterias 2013 Equity Incentive Plan [Member] | Asterias Biotherapeutics, Inc. [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Available for Grant, Beginning balance	5,190,000
Shares Available for Grant, Options granted	(490,000)
Shares Available for Grant, Options exercised
Shares Available for Grant, Options expired/ forfeited/cancelled	105,000
Shares Available for Grant, Ending balance	4,805,000	4,805,000
Number of Options Outstanding, Beginning balance
Number of Options Outstanding, Options granted	490,000
Number of Options Outstanding, Options exercised
Number of Options Outstanding, Options expired/forfeited/cancelled	(105,000)
Number of Options Outstanding, Ending balance	385,000	385,000
Number of Options Outstanding, Options exercisable
Number of RSUs Outstanding, Beginning balance
Number of RSUs Outstanding, Options granted
Number of RSUs Outstanding, Options exercised
Number of RSUs Outstanding, Options expired/forfeited/cancelled
Number of RSUs Outstanding, Ending balance
Weighted Average Exercise Price of Options Outstanding, beginning balance
Weighted Average Exercise Price of Options, Options granted	1.59
Weighted Average Exercise Price of Options, Options exercised
Weighted Average Exercise Price of Options, Options expired/forfeited/cancelled	1.63
Weighted Average Exercise Price of Options, Outstanding end balance	1.58	$ 1.58
Weighted Average Exercise Price of Options, Options exercisable