Cash and Cash Equivalents - Additional Information (Detail)	9 Months Ended
Sep. 30, 2013
Cash And Cash Equivalents [Abstract]
Maximum period to maturity to be considered a cash equivalent	90 days

Maximum period to maturity to be considered a cash equivalent.

No definition available.

Name:	idra_MaximumPeriodToMaturity
Namespace Prefix:	idra_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration