Collaborations	6 Months Ended
Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborations	10. Collaborations Maruishi Pharmaceutical Co., Ltd. In April 2013, the Company entered into the Maruishi Agreement under which the Company granted Maruishi an exclusive license to develop, manufacture, and commercialize drug products containing CR845 for acute pain and uremic pruritus in Japan. Maruishi has the right to grant sub-licenses in Japan, which entitle the Company to receive sub-license fees, net of prior payments made by Maruishi to the Company. Under the Maruishi Agreement, the Company and Maruishi are required to use commercially reasonable efforts, at their own expense, to develop, obtain regulatory approval for and commercialize CR845 in the United States and Japan, respectively. In addition, the Company provided Maruishi specific clinical development services for CR845 in Maruishi’s field of use. At inception of the Maruishi Agreement, the Company identified two deliverables under ASC 605-25: (1) the license; and (2) the R&D services specific to the uremic pruritus field of use, both of which were determined to have standalone value and have been accounted for as separate units of accounting from the outset of the arrangement. In March 2017, Maruishi entered into a sub-license agreement with Kissei Pharmaceutical Co. Ltd. for the development and sales/marketing of CR845 (called MR13A9 by Maruishi) for the treatment of uremic pruritus in dialysis patients in Japan. Consequently, during the six months ended June 30, 2017, the Company recognized revenue of $843 related to the sub-license fee. The Company allocated the amount of the sub-license fee to each of the two identified deliverables in the same proportion as the upfront license fee that the Company received at inception of the Maruishi Agreement. Accordingly, $530 was recognized as license and milestone fees revenue and $313 was recognized as collaborative revenue. The Company recognized clinical compound revenue of $0 and $79, during the three months ended June 30, 2017 and 2016, respectively, and $68 and $86 during the six months ended June 30, 2017 and 2016, respectively, from the sale of clinical compound to Maruishi. The Company incurred R&D expense related to the Maruishi Agreement of $0 and $72 during the three months ended June 30, 2017 and 2016, respectively, and $61 and $78 during the six months ended June 30, 2017 and 2016, respectively, consisting of cost of clinical compound.

10. Collaborations

Maruishi Pharmaceutical Co., Ltd.

In April 2013, the Company entered into the Maruishi Agreement under which the Company granted Maruishi an exclusive license to develop, manufacture, and commercialize drug products containing CR845 for acute pain and uremic pruritus in Japan. Maruishi has the right to grant sub-licenses in Japan, which entitle the Company to receive sub-license fees, net of prior payments made by Maruishi to the Company. Under the Maruishi Agreement, the Company and Maruishi are required to use commercially reasonable efforts, at their own expense, to develop, obtain regulatory approval for and commercialize CR845 in the United States and Japan, respectively. In addition, the Company provided Maruishi specific clinical development services for CR845 in Maruishi’s field of use.

At inception of the Maruishi Agreement, the Company identified two deliverables under ASC 605-25: (1) the license; and (2) the R&D services specific to the uremic pruritus field of use, both of which were determined to have standalone value and have been accounted for as separate units of accounting from the outset of the arrangement.

In March 2017, Maruishi entered into a sub-license agreement with Kissei Pharmaceutical Co. Ltd. for the development and sales/marketing of CR845 (called MR13A9 by Maruishi) for the treatment of uremic pruritus in dialysis patients in Japan. Consequently, during the six months ended June 30, 2017, the Company recognized revenue of $843 related to the sub-license fee. The Company allocated the amount of the sub-license fee to each of the two identified deliverables in the same proportion as the upfront license fee that the Company received at inception of the Maruishi Agreement. Accordingly, $530 was recognized as license and milestone fees revenue and $313 was recognized as collaborative revenue.

The Company recognized clinical compound revenue of $0 and $79, during the three months ended June 30, 2017 and 2016, respectively, and $68 and $86 during the six months ended June 30, 2017 and 2016, respectively, from the sale of clinical compound to Maruishi.

The Company incurred R&D expense related to the Maruishi Agreement of $0 and $72 during the three months ended June 30, 2017 and 2016, respectively, and $61 and $78 during the six months ended June 30, 2017 and 2016, respectively, consisting of cost of clinical compound.