Stockholders' Equity - Estimated Future Stock-Based Compensation Expense Relating to Unvested Stock Options (Details) (USD $)	Sep. 30, 2014
Stockholders Equity Note [Line Items]
Three months ended 2014	$ 2,371,612
2015	6,040,120
2016	1,595,568
Total	$ 10,007,300

Future Stock Based Compensation Expense Remainder Of Fiscal Year

No definition available.

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Namespace Prefix:	asmb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant