Organization and Description of Business	6 Months Ended
	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business Castlight Health, Inc. (“Castlight” or “the Company”) provides health navigation solutions for large U.S. employers and health plans (“customers”) and their respective employees and members (“users”). Castlight’s offerings deliver a personalized and simplified user experience that helps connect individuals with the right provider or available benefit at the right time. Castlight’s navigation offerings have demonstrated measurable results, driving increased levels of user satisfaction and program utilization and lower healthcare costs for its customers and millions of users. The Company was incorporated in the State of Delaware in January 2008. The Company's principal executive offices are located in San Francisco, California.