Organization (Details) medical_member in Millions	Mar. 31, 2017 medical_member county states
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of medical members | medical_member	40.6
Number of counties in the Kansas City area the Company does not serve	30
Number of counties in the New York City metropolitan area the Company serves as an independent licensee	10
Number of states in which the Company is licensed to conduct insurance operations | states	50