Note 1 - Description of Business, Going Concern and Basis of Presentation (Details Textual) - USD ($)						1 Months Ended	6 Months Ended	12 Months Ended
	Aug. 28, 2018	May 18, 2018	Mar. 28, 2018	Dec. 01, 2017	Aug. 03, 2016	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2018	Jun. 30, 2017	Jul. 07, 2017
Stock Issued During Period, Shares, New Issues			609,636	898,402	600,000
Common Stock, Par or Stated Value Per Share							$ 0.001	$ 0.001
Shares Issued, Price Per Share			$ 2.27	$ 3	$ 4.10
Class of Warrant or Right, Issued During Period								15,128,151
Payments of Stock Issuance Costs		$ 680,000	$ 171,000	$ 327,000	$ 369,000
Units Issued, Price per Unit		$ 0.60
Proceeds from Issuance or Sale of Equity, Total		$ 5,500,000
Proceeds from Issuance or Sale of Equity, Net		$ 4,820,000
Proceeds from Issuance of Common Stock, Net			$ 1,213,000	$ 2,368,000	$ 2,092,000		$ 2,368,000	$ 6,629,000	$ 2,092,000
Cash and Cash Equivalents, at Carrying Value, Ending Balance							3,513,000	2,400,000
Working Capital								2,261,000
Retained Earnings (Accumulated Deficit), Ending Balance							$ (187,640,000)	$ (227,435,000)
ThermoGenesis [Member]
Noncontrolling Interest, Ownership Percentage by Parent								80.00%
SynGen [Member]
Percentage Of Common Stock Issued To Acquiree Shareholders								20.00%		20.00%
Common Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 0.60
Warrants and Rights Outstanding, Term		5 years
Warrants Issused in Private Placement [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 2.68
Warrants and Rights Outstanding, Term			5 years 182 days
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			304,818
Units [Member]
Number of Units Issued		6,475,001
Convertible Units, Number of Common Shares Called by Each Unit		1
Convertible Units, Number of Common Warrants Called by Each Unit		1
Units [Member] | Common Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right		1
Pre-funded Units [member]
Number of Units Issued		2,691,666
Convertible Units, Number of Common Warrants Called by Each Unit		1
Convertible Units, Number of Pre-funded Warrants Called by Each Unit		1
Number of Units Exercised						2,691,666
Pre-funded Units [member] | Common Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right		1
Pre-funded Units [member] | Pre-funded Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right		1
Private Placement [Member]
Stock Issued During Period, Shares, New Issues	1,000,000
Common Stock, Par or Stated Value Per Share	$ 0.001
Shares Issued, Price Per Share	$ 0.18
Class of Warrant or Right, Issued During Period	2,965,000
Warrants Issued, Price Per Warrant	$ 0.17
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right	1
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.01
Proceeds from Issuance of Private Placement	$ 684,000
Proceeds from Issuance of Private Placement, Net	623,000
Payments of Stock Issuance Costs	$ 61,000
Boyalife Investment Fund II, Inc. [Member] | Revolving Credit Facility [Member]
Long-term Line of Credit, Total								$ 7,200,000
Line of Credit Facility, Maximum Borrowing Capacity								$ 10,000,000