Summary of Significant Accounting Policies - Accounts receivable (Details)
$ in Thousands
Dec. 31, 2016
|Allowance for doubtful accounts | $||$ 0|
|GlaxoSmithKline Intellectual Property Development Ltd|
|Number of customers | customer||1|
For an unclassified balance sheet, a valuation allowance for receivables due a company that are expected to be uncollectible.
Reference 1: http://www.xbrl.org/2003/role/presentationRef