Envision Healthcare Corporation is a provider of healthcare services. The Company offers a range clinical solutions, including physician-led services, medical transportation, ambulatory services and post-acute services. The Company operates through three segments: physician services, medical transportation and ambulatory services. The physician services segment includes the Company's hospital-based and non-hospital-based physician services business. The medical transportation segment includes the Company's community-based medical transportation services, including emergency 911, non-emergency, managed transportation, air ambulance and disaster response services. The ambulatory services segment includes the Company's ambulatory surgery business, which acquires, develops, owns and operates ambulatory surgery centers (ASCs) and surgical hospitals in partnership with physicians and health systems.