Organization	9 Months Ended
Sep. 30, 2013
Accounting Policies [Abstract]
Organization	(1) Organization Idera Pharmaceuticals, Inc. (“Idera” or the “Company”) is a clinical stage biotechnology company using its proprietary technology to create novel nucleic acid therapeutics designed to inhibit over-activation of Toll-like Receptors, or TLRs. The Company plans to develop and commercialize these therapeutics for the treatment of genetically defined forms of B-cell lymphoma and for orphan autoimmune diseases with serious unmet medical needs. The Company believes that clinical proof of concept of its approach of targeting specific TLRs for the treatment of psoriasis and potentially other autoimmune and inflammatory diseases has been established in a Phase 2 trial of one of its drug candidates. The Company’s lead drug candidate is IMO-8400, an antagonist for TLR7, TLR8, and TLR9 that is designed to block over-activation of the targeted TLRs. In a completed Phase 1 clinical trial of IMO-8400 in 42 healthy subjects, IMO-8400 was well tolerated and showed inhibition of TLR7, TLR8, and TLR9. The Company is conducting a randomized, double-blinded, placebo-controlled Phase 2 clinical trial of IMO-8400 in patients with moderate to severe plaque psoriasis. The Company has initiated plans for clinical development of IMO-8400 for the treatment of genetically defined forms of B-cell lymphoma. The Company has submitted an Investigational New Drug application, or IND, to the United States Food and Drug Administration, or FDA, to conduct a Phase 1/2 clinical trial of IMO-8400 in patients with Waldenström’s macroglobulinemia. The Company anticipates initiating this trial in the first quarter of 2014. The Company also plans to submit to the FDA in the first quarter of 2014 a protocol for a Phase 1/2 clinical trial of IMO-8400 in patients with diffuse large B-cell lymphoma, or DLBCL, that it expects to initiate in the first quarter of 2014. The Company has also selected IMO-9200, a second novel antagonist of TLR7, TLR8, and TLR9, for development as a drug candidate for potential use in selected autoimmune disease indications. The Company has initiated IND-enabling studies of IMO-9200 and expects to submit an IND for IMO-9200 in the third quarter of 2014. The Company had cash and cash equivalents of approximately $38,749,000 at September 30, 2013. The Company believes that its existing cash and cash equivalents will be sufficient to fund its operations at least through the second quarter of 2015. At September 30, 2013, the Company had an accumulated deficit of $406,794,000. The Company expects to incur substantial operating losses in future periods. The Company does not expect to generate product revenue or sales-based milestones or royalties until it successfully completes development and obtains marketing approval for drug candidates, either alone or in collaborations with third parties, which it expects will take a number of years. In order to commercialize its drug candidates, the Company needs to complete clinical development and to comply with comprehensive regulatory requirements. The Company is subject to a number of risks and uncertainties similar to those of other companies of the same size within the biotechnology industry, such as uncertainty of clinical trial outcomes, uncertainty of additional funding, and history of operating losses.

Organization

9 Months Ended

Sep. 30, 2013

(1) Organization

Idera Pharmaceuticals, Inc. (“Idera” or the “Company”) is a clinical stage biotechnology company using its proprietary technology to create novel nucleic acid therapeutics designed to inhibit over-activation of Toll-like Receptors, or TLRs. The Company plans to develop and commercialize these therapeutics for the treatment of genetically defined forms of B-cell lymphoma and for orphan autoimmune diseases with serious unmet medical needs. The Company believes that clinical proof of concept of its approach of targeting specific TLRs for the treatment of psoriasis and potentially other autoimmune and inflammatory diseases has been established in a Phase 2 trial of one of its drug candidates.

The Company’s lead drug candidate is IMO-8400, an antagonist for TLR7, TLR8, and TLR9 that is designed to block over-activation of the targeted TLRs. In a completed Phase 1 clinical trial of IMO-8400 in 42 healthy subjects, IMO-8400 was well tolerated and showed inhibition of TLR7, TLR8, and TLR9. The Company is conducting a randomized, double-blinded, placebo-controlled Phase 2 clinical trial of IMO-8400 in patients with moderate to severe plaque psoriasis.

The Company has initiated plans for clinical development of IMO-8400 for the treatment of genetically defined forms of B-cell lymphoma. The Company has submitted an Investigational New Drug application, or IND, to the United States Food and Drug Administration, or FDA, to conduct a Phase 1/2 clinical trial of IMO-8400 in patients with Waldenström’s macroglobulinemia. The Company anticipates initiating this trial in the first quarter of 2014. The Company also plans to submit to the FDA in the first quarter of 2014 a protocol for a Phase 1/2 clinical trial of IMO-8400 in patients with diffuse large B-cell lymphoma, or DLBCL, that it expects to initiate in the first quarter of 2014.

The Company has also selected IMO-9200, a second novel antagonist of TLR7, TLR8, and TLR9, for development as a drug candidate for potential use in selected autoimmune disease indications. The Company has initiated IND-enabling studies of IMO-9200 and expects to submit an IND for IMO-9200 in the third quarter of 2014.

The Company had cash and cash equivalents of approximately $38,749,000 at September 30, 2013. The Company believes that its existing cash and cash equivalents will be sufficient to fund its operations at least through the second quarter of 2015.

At September 30, 2013, the Company had an accumulated deficit of $406,794,000. The Company expects to incur substantial operating losses in future periods. The Company does not expect to generate product revenue or sales-based milestones or royalties until it successfully completes development and obtains marketing approval for drug candidates, either alone or in collaborations with third parties, which it expects will take a number of years. In order to commercialize its drug candidates, the Company needs to complete clinical development and to comply with comprehensive regulatory requirements.

The Company is subject to a number of risks and uncertainties similar to those of other companies of the same size within the biotechnology industry, such as uncertainty of clinical trial outcomes, uncertainty of additional funding, and history of operating losses.