Asset Contribution Agreement (Details) (USD $)	1 Months Ended		3 Months Ended	6 Months Ended
	Apr. 30, 2013	Jan. 31, 2013	Jun. 30, 2013 Tranche	Jun. 30, 2013 Tranche	Jun. 30, 2012	Apr. 10, 2013	Jan. 04, 2013 Tranche	Dec. 31, 2012
Asset Contribution Agreement [Line Items]
Stock issued during period (in shares)	810,000	540,000	1,350,000	2,594,156
Number of warrants issued (in shares)	389,999	259,999				350,000	650,000
Number of warrants to be issued by Asterias to Series A common shareholders (in shares)						8,000,000
Proceeds from issuance of common shares to a private investor				$ 23,810,421	$ 0
Number of tranches			2	2			2
Amount of Contribution funded Under Tranche One		2,000,000
Amount Of Contribution Funded Under Tranche Two			3,000,000
Number of shares held (in shares)						2,136,000
Bio Time potential ownership (in hundredths)			71.60%	71.60%
Percentage of equity interest owned by private investor (in hundredths)						7.00%
Exercise price of warrant (in dollars per share)			$ 6.59	$ 6.59		$ 5.00		$ 10.00
Warrant expiration term						3 years
Common Class B [Member]
Asset Contribution Agreement [Line Items]
Stock issued during period (in shares)			2,136,000
Number of warrants issued (in shares)							350,000
Proceeds from issuance of common shares to a private investor			5,000,000
Asterias Biotherapeutics [Member]
Asset Contribution Agreement [Line Items]
Stock issued during period (in shares)			8,902,077
Number of warrants issued (in shares)							8,000,000
Amount of contribution from investor			$ 5,000,000
Number of shares held (in shares)						21,773,340
Bio Time potential ownership (in hundredths)			71.60%	71.60%
Asterias Biotherapeutics [Member] | Common Class B [Member]
Asset Contribution Agreement [Line Items]
Number of warrants issued (in shares)						3,150,000
OrthoCyte Corporation [Member]
Asset Contribution Agreement [Line Items]
Percentage of subsidiary stock contributed (in hundredths)							10.00%
Cell Cure Neurosciences, Ltd. [Member]
Asset Contribution Agreement [Line Items]
Percentage of subsidiary stock contributed (in hundredths)							6.00%
Geron [Member]
Asset Contribution Agreement [Line Items]
Number of shares held (in shares)						6,537,779
Geron ownership (in hundredths)						21.40%