Asset Contribution Agreement (Details) (USD $)	1 Months Ended	3 Months Ended
	Jan. 31, 2013	Mar. 31, 2013	Mar. 31, 2012	Apr. 10, 2013	Jan. 04, 2013 Tranche
Asset Contribution Agreement [Line Items]
Stock issued during period (in shares)	540,000	1,350,000
Number of warrants issued (in shares)	259,999			350,000	650,000
Amount of contribution from investor		$ 5,000,000
Proceeds from issuance of common shares to a private investor		11,699,340	0
Number of tranches					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
Percentage of equity interest owned by private investor (in hundredths)				7.00%
Exercise price of warrant (in dollars per share)		$ 8.41		$ 5
Warrant expiration term				3 years
Agreement Termination Fees		1,800,000
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 ownership (in hundredths)				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%
Bio Time ownership (in hundredths)		100.00%
Cell Cure Neurosciences, Ltd. [Member]
Asset Contribution Agreement [Line Items]
Percentage of subsidiary stock contributed (in hundredths)					6.00%
Bio Time ownership (in hundredths)		62.50%
Geron [Member]
Asset Contribution Agreement [Line Items]
Number of shares held (in shares)				6,537,779
Geron ownership (in hundredths)				21.40%