Richard S. Foster is retiring this week after 18 years as the chief actuary for the Centers for Medicare and Medicaid Services. His duties included projecting Medicare and Medicaid spending and the cost of health care legislation to help policymakers weigh the impact on the federal budget. Some of those estimates got him into hot water with members of both parties. Foster recently sat down to discuss the highs and lows of his career with KHN's Mary Agnes Carey. What follows is an edited transcript of that conversation.