Shareholders' Equity - Equity Issuances (Details)		1 Months Ended		12 Months Ended
	Sep. 14, 2016 USD ($) clinical_trial_subject $ / shares	Feb. 28, 2018 USD ($)	Nov. 30, 2015 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 shares	Mar. 31, 2018 USD ($) shares
Class of Stock [Line Items]
Shares issued, price (in usd per share) | $ / shares	$ 4.72
Private Purchase Agreement [Member]
Class of Stock [Line Items]
Proceeds from issuance of common stock, initial closing	$ 6,600,000
Proceeds from issuance of common stock, second closing				$ 4,400,000
Stock issued (shares) | shares				900,000	1,400,000
Number of subjects for Phase 2 CLBS03 clinical trial, second closing | clinical_trial_subject	70
Aspire Capital Purchase Agreement [Member]
Class of Stock [Line Items]
Purchase commitment, remaining minimum amount committed			$ 30,000,000
Purchase commitment, maximum amount committed (shares) | shares			1,100,000
Term of agreement in months			24 months
Shares, issued | shares						319,776
Common stock issued, value						$ 1,500,000
H.C. Wainwright Sales Agreement [Member]
Class of Stock [Line Items]
Aggregate offering amount authorized per agreement		$ 12,000,000
Commission on gross proceeds due to third party (percent)		3.00%
Legal fees reimbursed to third party		$ 50,000
Quarterly filing fees payable, maximum		$ 2,500