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.

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Name:	us-gaap_ConversionOfStockLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Net Loss Per Share - Narrative (Details)	Feb. 13, 2017	Feb. 12, 2017
Preferred stock
Conversion of Stock [Line Items]
Exchange rate of common stock		1
Signal Shares issued to Miragen Common Shareholders \| Signal
Conversion of Stock [Line Items]
Exchange rate of common stock	0.7031