Business	12 Months Ended
Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Business	1. Business Cara Therapeutics, Inc., or the Company, is a clinical-stage biopharmaceutical corporation formed on July 2, 2004. The Company is focused on developing and commercializing new chemical entities designed to alleviate pruritus and pain by selectively targeting kappa opioid receptors. The Company’s primary activities to date have been organizing and staffing the Company, developing its product candidates, including conducting preclinical studies and clinical trials of CR845/difelikefalin-based product candidates and raising capital. As of December 31, 2017, the Company has raised aggregate net proceeds of approximately $291,100 from several rounds of equity financing, including its initial public offering, or IPO, which closed in February 2014 and two follow-on public offerings of common stock, which closed in April 2017 and August 2015, respectively, and the issuance of convertible preferred stock and debt prior to the IPO. In addition, the Company received approximately $33,500 under its license agreements for CR845/difelikefalin, primarily with Maruishi Pharmaceutical Co. Ltd., or Maruishi, and Chong Kun Dang Pharmaceutical Corp., or CKDP, and an earlier product candidate for which development efforts ceased in 2007 (see Note 11, Collaborations). On April 5, 2017, the Company completed its second follow-on public offering, raising aggregate proceeds of approximately $86,224, net of underwriting discounts and commissions and offering expenses paid by the Company. The offering was conducted pursuant to a shelf registration statement on Form S-3, which was filed on March 13, 2017 and declared effective by the Securities and Exchange Commission, or the SEC, on March 24, 2017 (see Note 9, Stockholders’ Equity). As of December 31, 2017, the Company had unrestricted cash and cash equivalents and marketable securities of $92,569 and an accumulated deficit of $220,341. The Company has incurred substantial net losses and negative cash flows from operating activities in nearly every fiscal period since inception and expects this trend to continue for the foreseeable future. The Company recognized a net loss of $58,125 and had net cash used in operating activities of $54,827 for the year ended December 31, 2017. The Company is subject to risks common to other life science companies including, but not limited to, uncertainty of product development and commercialization, lack of marketing and sales history, development by its competitors of new technological innovations, dependence on key personnel, market acceptance of products, product liability, protection of proprietary technology, ability to raise additional financing, and compliance with Food and Drug Administration, or FDA, and other government regulations. If the Company does not successfully commercialize any of its product candidates, it will be unable to generate recurring product revenue or achieve profitability.

1. Business

Cara Therapeutics, Inc., or the Company, is a clinical-stage biopharmaceutical corporation formed on July 2, 2004. The Company is focused on developing and commercializing new chemical entities designed to alleviate pruritus and pain by selectively targeting kappa opioid receptors. The Company’s primary activities to date have been organizing and staffing the Company, developing its product candidates, including conducting preclinical studies and clinical trials of CR845/difelikefalin-based product candidates and raising capital.

As of December 31, 2017, the Company has raised aggregate net proceeds of approximately $291,100 from several rounds of equity financing, including its initial public offering, or IPO, which closed in February 2014 and two follow-on public offerings of common stock, which closed in April 2017 and August 2015, respectively, and the issuance of convertible preferred stock and debt prior to the IPO. In addition, the Company received approximately $33,500 under its license agreements for CR845/difelikefalin, primarily with Maruishi Pharmaceutical Co. Ltd., or Maruishi, and Chong Kun Dang Pharmaceutical Corp., or CKDP, and an earlier product candidate for which development efforts ceased in 2007 (see Note 11, Collaborations).

On April 5, 2017, the Company completed its second follow-on public offering, raising aggregate proceeds of approximately $86,224, net of underwriting discounts and commissions and offering expenses paid by the Company. The offering was conducted pursuant to a shelf registration statement on Form S-3, which was filed on March 13, 2017 and declared effective by the Securities and Exchange Commission, or the SEC, on March 24, 2017 (see Note 9, Stockholders’ Equity).

As of December 31, 2017, the Company had unrestricted cash and cash equivalents and marketable securities of $92,569 and an accumulated deficit of $220,341. The Company has incurred substantial net losses and negative cash flows from operating activities in nearly every fiscal period since inception and expects this trend to continue for the foreseeable future. The Company recognized a net loss of $58,125 and had net cash used in operating activities of $54,827 for the year ended December 31, 2017.

The Company is subject to risks common to other life science companies including, but not limited to, uncertainty of product development and commercialization, lack of marketing and sales history, development by its competitors of new technological innovations, dependence on key personnel, market acceptance of products, product liability, protection of proprietary technology, ability to raise additional financing, and compliance with Food and Drug Administration, or FDA, and other government regulations. If the Company does not successfully commercialize any of its product candidates, it will be unable to generate recurring product revenue or achieve profitability.