Collaboration Agreements (EYLEA) (Details) - Collaboration Agreement with Bayer	9 Months Ended
Sep. 30, 2017
Minimum [Member]
Collaboration Agreement [Line Items]
Revenue based on percentage of annual sales in Japan	33.50%
Maximum [Member]
Collaboration Agreement [Line Items]
Revenue based on percentage of annual sales in Japan	40.00%

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.

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