Equity (Details) (USD $)	9 Months Ended				9 Months Ended			3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended		9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Restricted Stock [Member]	Sep. 30, 2014 Warrant [Member]	Sep. 30, 2014 2012 Equity Incentive Plan [Member] Restricted Stock [Member]	Sep. 30, 2013 2012 Equity Incentive Plan [Member] Restricted Stock [Member]	Sep. 30, 2014 Stock Option Plan 2002 [Member] Restricted Stock [Member]	Sep. 30, 2014 Michael D. West [Member]	Sep. 30, 2014 Michael D. West [Member]	Sep. 30, 2014 Robert W. Peabody [Member]	Sep. 30, 2014 Robert W. Peabody [Member]	Sep. 30, 2014 Asterias Biotherapeutics [Member]	Sep. 30, 2014 Series Preferred A Stock [Member]
Preferred Shares [Abstract]
Preferred shares, shares authorized (in shares)	2,000,000	2,000,000
Preferred shares outstanding (in shares)	70,000	0											70,000
Preferred stock dividend rate (in hundredths)													3.00%
Preferred share dividend (in dollars per shares)													$ 1.50
Share conversion price (in dollars per share)													$ 4.00
Common stock conversion ratio													12.5
Common Shares [Abstract]
Common shares, authorized (in shares)	125,000,000	125,000,000
Common shares, par value (in dollars per share)	$ 0	$ 0
Common shares, shares issued (in shares)	73,690,302	67,412,139
Common shares, shares outstanding (in shares)	68,291,760	56,714,424
Treasury stock (in shares)	5,398,542	10,697,715
Number of Shares Authorized (in shares)			4,000,000	9,195,002
Stock options granted (in shares)					1,410,000	1,575,000
Share options outstanding (in shares)							3,420,068
Exercise price of warrant (in dollars per share)				$ 5.00								$ 5.00
Number of warrants currently held to be distributed to holders of Series A Common Stock (in shares)	8,000,000
Options exercised (in shares)	2,060,400							1,470,400		475,000
Options exercised (in dollars per share)										$ 0.50
Warrants exercised (in shares)	0
Market value of shares on option exercise date (in dollars per share)	$ 2.65
Tax withholding obligation									434,013		89,623