CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Preferred Shares [Member]	Preferred Shares [Member] Asterias Biotherapeutics [Member]	Preferred Shares [Member] OncoCyte [Member]	Common Shares [Member]	Common Shares [Member] Asterias Biotherapeutics [Member]	Common Shares [Member] OncoCyte [Member]	Treasury Shares [Member]	Treasury Shares [Member] Asterias Biotherapeutics [Member]	Treasury Shares [Member] OncoCyte [Member]	Contributed Capital [Member]	Contributed Capital [Member] Asterias Biotherapeutics [Member]	Contributed Capital [Member] OncoCyte [Member]	Accumulated Deficit [Member]	Accumulated Deficit [Member] Asterias Biotherapeutics [Member]	Accumulated Deficit [Member] OncoCyte [Member]	Non-controlling Interest [Member]	Non-controlling Interest [Member] Asterias Biotherapeutics [Member]	Non-controlling Interest [Member] OncoCyte [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Accumulated Other Comprehensive Income/(Loss) [Member] Asterias Biotherapeutics [Member]	Accumulated Other Comprehensive Income/(Loss) [Member] OncoCyte [Member]	Total	Asterias Biotherapeutics [Member]	OncoCyte [Member]
BALANCE at Dec. 31, 2013	$ 0			$ 203,456			$ (43,034)			$ 94			$ (145,778)			$ 27,461			$ 62			$ 42,261
BALANCE (in shares) at Dec. 31, 2013	0			67,412,000			(10,698,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Sale of common shares, net of fees paid and amortized	$ 0			$ 43,827			$ 0			0			0			0			0			43,827
Sale of common shares, net of fees paid and amortized (in shares)	0			14,173,000			0
Exercise of options	$ 0			$ 1,192			$ 0			0			0			0			0			1,192
Exercise of options (in shares)	0			2,060,000			0
Shares retired as part of exercise of options	$ 0			$ (973)			$ 0			0			0			0			0			(973)
Shares retired as part of exercise of options (in shares)	0			(367,000)			0
Shares retired to pay for employee's taxes	$ 0			$ (415)			$ 0			0			0			0			0			(415)
Shares retired to pay for employee's taxes (in shares)	0			(156,000)			0
Tax liability on treasury shares sold by Asterias	$ 0			$ (3,611)			$ 0			0			0			0			0			(3,611)
Stock options granted for compensation	0			2,409			0			0			0			0			0			2,409
Stock options granted for compensation in subsidiaries	0			0			0			0			0			1,808			0			1,808
Restricted stock granted for compensation	0			0			0			0			0			234			0			234
Subsidiary warrants issued to outside investors as part of sale of treasury stock	0			0			0			0			0			3,184			0			3,184
Sale of treasury stock	$ 0			$ (11,042)			$ 23,144			0			0			0			0			12,102
Sale of treasury stock (in shares)	0			0			5,804,000
Sale of preferred stock	$ 3,500			$ 0			$ 0			0			0			0			0			3,500
Sale of preferred stock (in shares)	70,000			0			0
Dividends on preferred stock	$ 0			$ 0			$ 0			(87)			0			0			0			(87)
Outside investment in subsidiary with cash	0			0			0			0			0			939			0			939
Exercise of subsidiary options	0			0			0			0			0			8			0			8
Foreign currency translation adjustment	0			0			0			0			0			0			125			125
Unrealized loss on available-for-sale securities	0			0			0			0			0			0			(1)			(1)
NET INCOME (LOSS)	0			0			0			0			(36,412)			(7,367)			0			(43,779)
BALANCE at Dec. 31, 2014	$ 3,500			$ 234,843			$ (19,890)			7			(182,190)			26,267			186			62,723
BALANCE (in shares) at Dec. 31, 2014	70,000			83,122,000			(4,894,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Sale of common shares, net of fees paid and amortized	$ 0			$ 33,897			$ 0			0			0			0			0			33,897
Sale of common shares, net of fees paid and amortized (in shares)	0			10,738,000			0
Exercise of options	$ 0			$ 621			$ 0			0			0			0			0			621
Exercise of options (in shares)	0			155,000			0
Shares retired as part of exercise of options																						0
Warrants exercised	$ 0			$ 19			$ 0			0			0			0			0			19
Warrants exercised (in shares)	0			4,000			0
Stock options granted for compensation	$ 0			$ 2,003			$ 0			0			0			0			0			2,003
Stock options granted for compensation in subsidiaries	0			0			0			0			0			8,223			0			8,223
Restricted stock granted for compensation	0			0			0			0			0			822			0			822
Dividend in kind	0			0			0			0			(712)			712			0			0
Subsidiary shares retired to pay for employee's taxes	0			0			0			0			0			(98)			0			(98)
Subsidiary warrants exercised	0			0			0			0			0			11,700			0			11,700
Contingently issuable subsidiary warrants	0			0			0			0			0			65			0			65
Sale of treasury stock	$ 0			$ (496)			$ 1,857			0			0			0			0			1,361
Sale of treasury stock (in shares)	0			0			421,000
Conversion of preferred stock to common stock	$ (3,500)			$ 3,500			$ 0			0			0			0			0			0
Conversion of preferred stock to common stock (in shares)	(70,000)			875,000			0
Dividends on preferred stock	$ 0			$ (408)			$ 0			(7)			0			0			0			(415)
Subsidiary shares issued in lieu of cash for services received	0			0			0			0			0			486			0			486
Outside investment in subsidiary with cash	0			0			0			0			0			3,918			0			3,918
Sale of subsidiary shares at- the- market, net of fees paid and amortized	0			0			0			0			0			9,646			0			9,646
Exercise of subsidiary options	0			0			0			0			0			33			0			33
Foreign currency translation adjustment	0			0			0			0			0			0			(424)			(424)
Unrealized loss on available-for-sale securities	0			0			0			0			0			0			1			1
NET INCOME (LOSS)	0			0			0			0			(46,991)			(11,143)			0			(58,134)
BALANCE at Dec. 31, 2015	$ 0			$ 273,979			$ (18,033)			0			(229,893)			50,631			(237)			$ 76,447
BALANCE (in shares) at Dec. 31, 2015	0			94,894,000			(4,473,000)															90,421,554
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Sale of common shares, net of fees paid and amortized	$ 0			$ 18,606			$ 0			0			0			0			0			$ 18,606
Sale of common shares, net of fees paid and amortized (in shares)	0			8,420,000			0
Common shares issued for executive bonus in lieu of cash	$ 0			$ 200			$ 0			0			0			0			0			200
Common shares issued for executive bonus in lieu of cash (in shares)	0			68,000			0
Common shares issued for consulting services in lieu of cash	$ 0			$ 40			$ 0			0			0			0			0			40
Common shares issued for consulting services in lieu of cash (in shares)	0			14,000			0
Stock options granted for compensation	$ 0			$ 2,731			$ 0			0			0			0			0			2,731
Stock options granted for compensation in subsidiaries	0			0			0			0			0			5,220			0			5,220
Dividends on preferred stock																						0
Deconsolidation of Asterias	$ 0			$ 0			$ 15,142			0			0			(21,752)			0			(6,610)
Deconsolidation of Asterias (in shares)	0			0			3,853,000
Subsidiary financing transactions with noncontrolling interests		$ 0	$ 0		$ 18,310	$ 4,012		$ 0	$ 0		$ 0	$ 0		$ 0	$ 0		$ (18,310)	$ (4,012)		$ 0	$ 0		$ 0	$ 0
Distribution of Asterias warrants to its shareholders other than BioTime	$ 0			$ 0			$ 0			0			0			3,125			0			3,125
Exercise of subsidiary options	0			0			0			0			0			2,151			0			2,151
Sale of common shares and warrants by OncoCyte, net of financing fees	0			0			0			0			0			9,777			0			9,777
Beneficial conversion feature on convertible debt issued to Cell Cure's noncontrolling interests	0			0			0			0			0			701			0			701
Foreign currency translation adjustment	0			0			0			0			0			0			(106)			(106)
Unrealized loss on available-for-sale securities	0			0			0			0			0			0			(395)			(395)
NET INCOME (LOSS)	0			0			0			0			33,572			(14,951)			0			18,621
BALANCE at Dec. 31, 2016	$ 0			$ 317,878			$ (2,891)			$ 0			$ (196,321)			$ 12,580			$ (738)			$ 130,508
BALANCE (in shares) at Dec. 31, 2016	0			103,396,000			(620,000)															102,776,539	21,700,000