Based on the outcome of our 2016 Medicare PDP bids, our plans are below the benchmarks in 17 of the 34 CMS regions and within the de minimus range of the benchmark in nine other regions. Comparatively, in 2015, our plans were below the benchmark in 13 of the 33 regions where we submitted bids and within the de minimus range in nine other regions.
In March 2015, our Missouri Care, Incorporated ("Missouri Care") health plan was selected to continue serving Medicaid recipients participating in the MO HealthNet Managed Care program. The new contract commenced on July 1, 2015 and is for one year with two renewal options. As of December 31, 2015, Missouri Care served approximately 114,000 MO HealthNet Managed Care Medicaid members.
Medicare Health Plans. Membership decreased by 63,000, or 15.1%, compared to December 31, 2014. The decrease is due to a reduction in our California and New York Medicare membership due to bid actions and county withdrawals in 2015, as well as our exit from the Arizona, Missouri and Ohio MA markets. The reduction also reflects the divestiture of our Medicare Supplement business, which was completed on July 1, 2015. These decreases are partially offset by organic membership growth in Florida and Texas.
A reconciliation of SG&A expense, including and excluding such costs, is presented below.
During the year ended December 31, 2015, we recognized a $6.1 million pre-tax gain resulting from the July 2015 divestiture of Sterling.
Medical benefits expense for the year ended December 31, 2015 increased by approximately $1.0 billion, or 14.8%, compared to the same period in 2014, primarily driven by the increase in membership. Our Medicaid Health Plans MBR decreased by 150 basis points for the year ended December 31, 2015 compared with 2014. Our Medicaid Health Plans Adjusted MBR decreased by 70 basis points for the year ended December 31, 2015 compared with 2014, primarily due to improved operating performance across the segment, in particular in our Florida MMA program, which included a rate increase for this program that was effective September 1, 2015, as well as unfavorable prior year reserve development recognized in 2014. The decrease was partially offset by a rate decrease in Kentucky that was effective July 1, 2015.
We will continue to focus on three main objectives in MA, including execution on medical expense and quality initiatives, a more disciplined portfolio approach to our MA bids, including a focus on net income, and improving Star Ratings, both in terms of execution on quality initiatives and our advocacy position to properly match the ratings, rules and economics with the prevalent data that demonstrates the causal connection between socio-economic status and lower quality ratings.
Interest Expense - We expect that interest expense will increase to approximately $58.0 million to $62.0 million in 2016, driven primarily by the additional $300.0 million issuance of Senior Notes in June 2015.
On January 8, 2016, we entered into a senior unsecured revolving credit facility (the “2016 Credit Agreement”) with an initial aggregate principal amount at any time outstanding not to exceed $850.0 million. We then repaid our $300.0 million Term Loan and terminated the 2014 Credit Agreement. The 2016 Credit Agreement provides for a senior unsecured revolving loan facility (the “2016 Revolving Credit Facility”) of up to $850.0 million (the loans thereunder, the “Revolving Credit Loans”), of which up to $150.0 million is available for letters of credit. The 2016 Credit Agreement also provides that we may, at our option, increase the aggregate amount of the 2016 Revolving Credit Facility and/or obtain incremental term loans in an amount up to $200.0 million without the consent of any lenders not participating in such increase, subject to certain customary conditions and lenders committing to provide the increase in funding. There can be no assurance that additional funding will become available. Unutilized commitments under the Credit Agreement are subject to a fee of 0.25% to 0.35% depending upon our ratio of total net debt to cash flow.
Our MA and PDP premiums are subject to risk sharing through the CMS Medicare Part D risk corridor provisions. The risk corridor calculation compares our actual experience to the target amount of prescription drug costs, limited to costs under the standard coverage as defined by CMS, less rebates included in our submitted plan year bid. We receive additional premium from CMS if our actual experience is more than 5% above the target amount. We refund premiums to CMS if our actual experience is more than 5% below the target amount. Based on the risk corridor provision and PDP activity-to-date, an estimated risk-sharing receivable or payable is recorded as an adjustment to premium revenue. After the close of the annual plan year, CMS performs the risk corridor calculation and any differences are settled between CMS and our plans. Historically, we have not experienced material differences between the subsequent CMS settlement amount and our estimates.
The cost of medical benefits is recognized in the period in which services are provided and includes an estimate of the cost of incurred but not reported ("IBNR") direct medical benefits expense. Medical benefits payable includes estimates for IBNR, amounts for claims fully adjudicated but not yet paid and certain medically-related administrative costs. Direct medical expenses include amounts paid or payable to hospitals, physicians, pharmacy benefit managers and providers of ancillary services. Recorded direct medical expenses are reduced by the amount of pharmacy rebates earned, which are estimated based on historical utilization of specific pharmaceuticals, current utilization and contract terms. Pharmacy rebates earned but not yet received from pharmaceutical manufacturers are included in pharmacy rebates receivable in the accompanying consolidated balance sheets. Direct medical expenses may also include reserves for estimated referral claims related to health care providers under contract with us who are financially troubled or insolvent and who may not be able to honor their obligations for the costs of medical services provided by other providers. In these instances, we may be required to honor these obligations for legal or business reasons. Based on our current assessment of providers under contract with us, such losses have not been and are not expected to be significant. Also, included in direct medical expense are estimates for provider settlements due to clarification of contract terms, out-of-network reimbursement, claims payment differences and amounts due to contracted providers under risk-sharing arrangements. Medically-related administrative costs include preventive health and wellness, care management, case and disease management, and other quality improvement costs. Other medically-related administrative costs such as utilization review services, network and provider credentialing and claims handling costs, are recorded in selling, general, and administrative expenses.