Subsequent Events - Narratives (Details) - Subsequent Event [Member] - PTC Therapeutics [Member] $ in Millions	May 03, 2019 USD ($)
Subsequent Event [Line Items]
License fee receivable	$ 6.0
Ionis [Member]
Subsequent Event [Line Items]
Sublicense fee payable	$ 3.0

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

No definition available.

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Period Type:	duration