Annual report pursuant to Section 13 and 15(d)

Stockholders' equity - Common Stock and Receivable from Shareholder (Details)

v2.4.1.9
Stockholders' equity - Common Stock and Receivable from Shareholder (Details) (USD $)
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Feb. 13, 2013
Class of Stock [Line Items]      
Common stock, shares outstanding 15,905,881us-gaap_CommonStockSharesOutstanding 15,155,200us-gaap_CommonStockSharesOutstanding  
Preferred stock, shares authorized     10,000,000us-gaap_PreferredStockSharesAuthorized
Common stock      
Class of Stock [Line Items]      
Shares of common stock issued in private placements 647,706us-gaap_StockIssuedDuringPeriodSharesNewIssues
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember 		   
Private placements, price in usd per share $ 4.75tcgn_StockIssuedDuringPeriodPricePerShare
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember 		   
Stock issuance costs $ 742,709.51us-gaap_PaymentsOfStockIssuanceCosts
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember 		   
Net cash proceeds from private placements 2,333,894us-gaap_ProceedsFromIssuanceOfPrivatePlacement
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember 		   
Private Placement | Common stock      
Class of Stock [Line Items]      
Shares of common stock issued in private placements 1,400us-gaap_StockIssuedDuringPeriodSharesNewIssues
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_PrivatePlacementMember 		1,476,789us-gaap_StockIssuedDuringPeriodSharesNewIssues
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_PrivatePlacementMember 		 
Net cash proceeds from private placements $ 6,300us-gaap_ProceedsFromIssuanceOfPrivatePlacement
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_PrivatePlacementMember 		$ 5,966,805us-gaap_ProceedsFromIssuanceOfPrivatePlacement
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_PrivatePlacementMember 		 
Private Placement | Common stock | Maximum      
Class of Stock [Line Items]      
Private placements, price in usd per share   $ 4.50tcgn_StockIssuedDuringPeriodPricePerShare
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_PrivatePlacementMember