Capital Stock - Common Stock Purchase Agreement - Additional Information (Details) - Novartis AG [Member] $ / shares in Units, $ in Millions  | 
 Aug. 24, 2017  
USD ($)  
$ / shares  
shares 
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| Class Of Warrant Or Right [Line Items] | |
| Number of common stock agreed to issue and sell | shares | 539,131 | 
| Common stock sale price | $ / shares | $ 9.2742 | 
| Aggregate purchase price of common stock agreed to issue and sell | $ 5.0 | 
| Common stock aggregate fair value | $ 4.8 | 
| Common stock closing price | $ / shares | $ 8.93 | 
| Common stock purchase agreement date | Aug. 24, 2017 | 
| Common stock premium | $ 0.2 | 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Definition Cash received on stock transaction after deduction of issuance costs. No definition available. 
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- Definition The number of shares issued or sold by the subsidiary or equity method investee per stock transaction. No definition available. 
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- Definition Date the subsidiary or equity investee issued or sold stock, in CCYY-MM-DD format. No definition available. 
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- Definition Price of a single share of a number of saleable stocks of a company. No definition available. 
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- Definition Aggregate fair value of common stock. No definition available. 
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- Definition Closing stock price per share. No definition available. 
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- Definition Common stock premium. No definition available. 
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- Details 
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