Income Taxes (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Tax Credit Carryforward [Line Items]
Gain on deconsolidation of Asterias	$ 49,048,000	$ 0	$ 49,048,000	$ 0
Deferred income tax benefit	$ 0	$ (1,271,000)	0	(2,448,000)
Deferred income tax benefit, federal				2,600,000
Deferred income tax expense (benefit), state taxes				$ 154,000
Asterias Biotherapeutics [Member]
Tax Credit Carryforward [Line Items]
Gain on deconsolidation of Asterias			$ 49,000,000