GUARANTEES AND CONTINGENCIES	9 Months Ended
GUARANTEES AND CONTINGENCIES	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
GUARANTEES AND CONTINGENCIES	GUARANTEES AND CONTINGENCIES Government Contracts Our Medicare products, which accounted for approximately 74% of our total premiums and services revenue for the nine months ended September 30, 2016, primarily consisted of products covered under the Medicare Advantage and Medicare Part D Prescription Drug Plan contracts with the federal government. These contracts are renewed generally for a calendar year term unless CMS notifies us of its decision not to renew by May 1 of the calendar year in which the contract would end, or we notify CMS of our decision not to renew by the first Monday in June of the calendar year in which the contract would end. All material contracts between Humana and CMS relating to our Medicare products have been renewed for 2017, and all of our product offerings filed with CMS for 2017 have been approved. CMS uses a risk-adjustment model which apportions premiums paid to Medicare Advantage, or MA, plans according to health severity of covered members. The risk-adjustment model pays more for enrollees with predictably higher costs. Under this model, rates paid to MA plans are based on actuarially determined bids, which include a process whereby our prospective payments are based on a comparison of our beneficiaries’ risk scores, derived from medical diagnoses, to those enrolled in the government’s traditional fee-for-service Medicare program (referred to as "Medicare FFS"). Under the risk-adjustment methodology, all MA plans must collect and submit the necessary diagnosis code information from hospital inpatient, hospital outpatient, and physician providers to CMS within prescribed deadlines. The CMS risk-adjustment model uses the diagnosis data to calculate the risk-adjusted premium payment to MA plans, which CMS adjusts for coding pattern differences between the health plans and the government fee-for-service program. We generally rely on providers, including certain providers in our network who are our employees, to code their claim submissions with appropriate diagnoses, which we send to CMS as the basis for our payment received from CMS under the actuarial risk-adjustment model. We also rely on these providers to document appropriately all medical data, including the diagnosis data submitted with claims. In addition, we conduct medical record reviews as part of our data and payment accuracy compliance efforts, to more accurately reflect diagnosis conditions under the risk adjustment model. These compliance efforts include the internal contract level audits described in more detail below. CMS is continuing to perform audits of various companies’ selected MA contracts related to this risk adjustment diagnosis data. We refer to these audits as Risk-Adjustment Data Validation Audits, or RADV audits. RADV audits review medical records in an attempt to validate provider medical record documentation and coding practices which influence the calculation of premium payments to MA plans. In 2012, CMS released a “Notice of Final Payment Error Calculation Methodology for Part C Medicare Advantage Risk Adjustment Data Validation (RADV) Contract-Level Audits.” The payment error calculation methodology provides that, in calculating the economic impact of audit results for an MA contract, if any, the results of the audit sample will be extrapolated to the entire MA contract based upon a comparison to “benchmark” audit data in Medicare FFS (which we refer to as the "FFS Adjuster"). This comparison to the FFS Adjuster is necessary to determine the economic impact, if any, of audit results because the government program data set, including any attendant errors that are present in that data set, provides the basis for MA plans’ risk adjustment to payment rates. CMS already makes other adjustments to payment rates based on a comparison of coding pattern differences between MA plans and Medicare FFS data (such as for frequency of coding for certain diagnoses in MA plan data versus the government program data set). The final methodology, including the first application of extrapolated audit results to determine audit settlements, is expected to be applied to RADV contract level audits conducted for contract year 2011 and subsequent years. CMS is currently conducting RADV contract level audits for contract years 2011, 2012 and 2013, in which two, five, and five of our Medicare Advantage plans are being audited, respectively. Per CMS guidance, selected MA contracts will be notified of an audit at some point after the close of the final reconciliation for the payment year being audited. The final reconciliation occurs in August of the calendar year following the payment year. Estimated audit settlements are recorded as a reduction of premiums revenue in our consolidated statements of income, based upon available information. We perform internal contract level audits based on the RADV audit methodology prescribed by CMS. Included in these internal contract level audits is an audit of our Private Fee-For-Service business which we used to represent a proxy of the FFS Adjuster which has not yet been released. We based our accrual of estimated audit settlements for each contract year on the results of these internal contract level audits and update our estimates as each audit is completed. Estimates derived from these results were not material to our results of operations, financial position, or cash flows. However, as indicated, we are awaiting additional guidance from CMS regarding the FFS Adjuster. Accordingly, we cannot determine whether such RADV audits will have a material adverse effect on our results of operations, financial position, or cash flows. In addition, CMS' comments in formalized guidance regarding “overpayments” to MA plans appear to be inconsistent with CMS' prior RADV audit guidance. These statements, contained in the preamble to CMS’ final rule release regarding Medicare Advantage and Part D prescription drug benefit program regulations for Contract Year 2015, appear to equate each Medicare Advantage risk adjustment data error with an “overpayment” without reconciliation to the principles underlying the FFS Adjuster referenced above. We will continue to work with CMS to ensure that MA plans are paid accurately and that payment model principles are in accordance with the requirements of the Social Security Act, which, if not implemented correctly could have a material adverse effect on our results of operations, financial position, or cash flows. At September 30, 2016, our military services business, which accounted for approximately 1% of our total premiums and services revenue for the nine months ended September 30, 2016, primarily consisted of the TRICARE South Region contract. The current 5-year South Region contract, which expires March 31, 2017, is subject to annual renewals on April 1 of each year during its term at the government’s option. On March 30, 2016, we received notice the Defense Health Agency, or DHA, exercised its option to extend the TRICARE South Region contract through March 31, 2017. The next generation of TRICARE contracts that are expected to become effective on April 1, 2017, consolidates three regions into two - East and West, with the current North Region and South Region combined to form the East Region. On July 21, 2016, we were notified by the DHA that we were awarded the contract for the TRICARE East Region. The next generation East Region and West Region contract awards are currently subject to protests before the Government Accountability Office, or GAO, by unsuccessful bidders. Our state-based Medicaid business accounted for approximately 5% of our total premiums and services revenue for the nine months ended September 30, 2016. In addition to our state-based Temporary Assistance for Needy Families, or TANF, Medicaid contracts in Florida and Kentucky, we have contracts in Florida for Long Term Support Services (LTSS), Illinois and Virginia for stand-alone dual eligible demonstration programs serving individuals dually eligible for both the federal Medicare program and the applicable state-based Medicaid program as well as an Integrated Care Program, or ICP, Medicaid contract in Illinois. The loss of any of the contracts above or significant changes in these programs as a result of legislative or regulatory action, including reductions in premium payments to us, regulatory restrictions on profitability, including by comparison of our Medicare Advantage profitability to our non-Medicare Advantage business profitability and a requirement that they remain within certain ranges of each other, or increases in member benefits without corresponding increases in premium payments to us, may have a material adverse effect on our results of operations, financial position, and cash flows. Legal Proceedings and Certain Regulatory Matters Florida Matters On January 6, 2012, the Civil Division of the United States Attorney’s Office for the Southern District of Florida advised us that it is seeking documents and information from us and several of our affiliates relating to several matters including the coding of medical claims by one or more South Florida medical providers, and loans to physician practices. On May 1, 2014, the U.S. Attorney's Office filed a Notice of Non-Intervention in connection with a civil qui tam suit related to one of these matters captioned United States of America ex rel. Olivia Graves v. Plaza Medical Centers, et al., and the Court ordered the complaint unsealed. Subsequently, the individual plaintiff amended the complaint and served the Company, opting to continue to pursue the action. The individual plaintiff has filed a fourth amended complaint which we answered on February 19, 2016. The Court has ordered trial to commence on February 20, 2017 if the matter is not resolved prior to trial. We continue to cooperate with and respond to information requests from the U.S. Attorney’s office. These matters could result in additional qui tam litigation. As previously disclosed, the Civil Division of the United States Department of Justice had provided us with an information request, separate from but related to the Plaza Medical matter, concerning our Medicare Part C risk adjustment practices. The request relates to our oversight and submission of risk adjustment data generated by providers in our Medicare Advantage network, including the providers identified in the Plaza Medical matter, as well as to our business and compliance practices related to risk adjustment data generated by our providers and by us, including medical record reviews conducted as part of our data and payment accuracy compliance efforts, the use of health and well-being assessments, and our fraud detection efforts. We believe that this request for information is in connection with a wider review of Medicare Risk Adjustment generally that includes a number of Medicare Advantage plans, providers and vendors. We continue to cooperate with and voluntarily respond to the information requests from the Department of Justice and the U.S. Attorney’s Office. These matters are expected to result in additional qui tam litigation. On June 16, 2015, the U.S. Attorney’s Office filed a Declination Notice, indicating its intent not to intervene, in connection with a civil qui tam suit captioned U.S. ex rel. Ramsey-Ledesma v. Censeo, et al., and the Court ordered the complaint unsealed. Subsequently, the individual plaintiff filed a second amended complaint and served the Company, opting to continue to pursue the action. The plaintiff’s second amended complaint names several other defendants, including CenseoHealth. On January 8, 2016, we and the other defendants each filed a motion to dismiss the second amended complaint, and on September 30, 2016, our motion to dismiss was granted in its entirety. The plaintiff has reserved the right to appeal the grant of our motion after the litigation concludes. Litigation Related to the Merger DOJ Action On July 21, 2016, the United States government (acting under the U.S. Attorney General), along with the states of Delaware, Florida, Georgia, Illinois, Iowa and Ohio, the commonwealths of Pennsylvania and Virginia, and the District of Columbia, acting by and through their respective attorneys general, filed a civil complaint against us and Aetna in the U.S. District Court for the District of Columbia (we refer to this as the DOJ Action). The complaint alleges, among other things, that the proposed Merger would violate Section 7 of the Clayton Antitrust Act and seeks a permanent injunction to prevent the Merger. The Court has scheduled trial to commence on December 5, 2016. We cannot predict when the DOJ litigation will be resolved. Together with Aetna, we intend to vigorously defend the Merger in response to the lawsuit. Shareholder Action In connection with the Merger, three putative class action complaints were filed by purported Humana stockholders challenging the Merger, two in the Circuit Court of Jefferson County, Kentucky and one in the Court of Chancery of the State of Delaware. The complaints are captioned Solak v. Broussard et al., Civ. Act. No. 15CI03374 (Kentucky state court), Litwin v. Broussard et al., Civ. Act. No. 15CI04054 (Kentucky state court) and Scott v. Humana Inc. et al., C.A. No. 11323-VCL (Delaware state court). The complaints named as defendants each member of Humana’s board of directors, Aetna, and, in the case of the Delaware complaint, Humana. The complaints generally alleged, among other things, that the individual members of our board of directors breached their fiduciary duties owed to our stockholders by entering into the Merger Agreement, approving the mergers as contemplated by the Merger Agreement, and failing to take steps to maximize the value of Humana to our stockholders, and that Aetna, and, in the case of the Delaware complaint, Humana aided and abetted such breaches of fiduciary duties. In addition, the complaints alleged that the merger undervalues Humana, that the process leading up to the execution of the Merger Agreement was flawed, that the members of our board of directors improperly placed their own financial interests ahead of those of our stockholders, and that certain provisions of the Merger Agreement improperly favor Aetna and impede a potential alternative transaction. Among other remedies, the complaints sought equitable relief rescinding the Merger Agreement and enjoining the defendants from completing the mergers as well as costs and attorneys’ fees. We refer to all these cases collectively in this report as the Merger Litigation. On August 20, 2015, the parties in the Kentucky state cases filed a stipulation and proposed order with the court to consolidate these cases into a single action captioned In re Humana Inc. Shareholder Litigation, Civ. Act. No. 15CI03374. On October 9, 2015, solely to avoid the costs, risks, and uncertainties inherent in litigation, and without admitting any liability or wrongdoing, we and the other named defendants in the Merger Litigation signed a memorandum of understanding, which we refer to as the MOU, to settle the Merger Litigation. Subject to court approval and further definitive documentation in a stipulation of settlement that will be subject to customary conditions, the MOU resolved the claims brought in the Merger Litigation and provided that we would make certain additional disclosures related to the proposed mergers. The MOU further provided for, among other things, dismissal of the Merger Litigation with prejudice and a release and settlement by the purported class of our stockholders of all claims against the defendants and their affiliates and agents in connection with the Merger Agreement and transactions and disclosures related to the Merger Agreement. The asserted claims will not be released until such stipulation of settlement receives court approval. The foregoing terms and conditions will be defined by the stipulation of settlement, and class members will receive a separate notice describing the settlement terms and their rights in connection with the approval of the settlement. In connection with the settlement, the parties contemplate that plaintiffs’ counsel will file a petition for an award of attorneys’ fees and expenses. We will pay or cause to be paid any court awarded attorneys’ fees and expenses. There can be no assurance that the parties will ultimately enter into a stipulation of settlement or that a court will approve such settlement even if the parties were to enter into such stipulation. In such event, the proposed settlement as contemplated by the MOU may be terminated. Because the MOU contemplates that the Kentucky court will be asked to approve the settlement, the plaintiffs have already withdrawn the Delaware case. Other Lawsuits and Regulatory Matters Our current and past business practices are subject to review or other investigations by various state insurance and health care regulatory authorities and other state and federal regulatory authorities. These authorities regularly scrutinize the business practices of health insurance, health care delivery and benefits companies. These reviews focus on numerous facets of our business, including claims payment practices, statutory capital requirements, provider contracting, risk adjustment, competitive practices, commission payments, privacy issues, utilization management practices, pharmacy benefits, access to care, and sales practices, among others. Some of these reviews have historically resulted in fines imposed on us and some have required changes to some of our practices. We continue to be subject to these reviews, which could result in additional fines or other sanctions being imposed on us or additional changes in some of our practices. We also are involved in various other lawsuits that arise, for the most part, in the ordinary course of our business operations, certain of which may be styled as class-action lawsuits. Among other matters, this litigation may include employment matters, claims of medical malpractice, bad faith, nonacceptance or termination of providers, anticompetitive practices, improper rate setting, provider contract rate disputes, failure to disclose network discounts and various other provider arrangements, general contractual matters, intellectual property matters, and challenges to subrogation practices. For example, a number of hospitals and other providers have asserted that, under their network provider contracts, we are not entitled to reduce Medicare Advantage payments to these providers in connection with changes in Medicare payment systems and in accordance with the Balanced Budget and Emergency Deficit Control Act of 1985, as amended (commonly referred to as “sequestration”). Those challenges have led and could lead to arbitration demands or other litigation. Also, under state guaranty assessment laws, including those related to state cooperative failures in the industry, we may be assessed (up to prescribed limits) for certain obligations to the policyholders and claimants of insolvent insurance companies that write the same line or lines of business as we do. As a government contractor, we may also be subject to qui tam litigation brought by individuals who seek to sue on behalf of the government, alleging that the government contractor submitted false claims to the government including, among other allegations, those resulting from coding and review practices under the Medicare risk adjustment model. Qui tam litigation is filed under seal to allow the government an opportunity to investigate and to decide if it wishes to intervene and assume control of the litigation. If the government does not intervene, the lawsuit is unsealed, and the individual may continue to prosecute the action on his or her own, on behalf of the government. We also are subject to other allegations of non-performance of contractual obligations to providers, members, and others, including failure to properly pay claims, improper policy terminations, challenges to our implementation of the Medicare Part D prescription drug program and other litigation. A limited number of the claims asserted against us are subject to insurance coverage. Personal injury claims, claims for extracontractual damages, care delivery malpractice, and claims arising from medical benefit denials are covered by insurance from our wholly owned captive insurance subsidiary and excess carriers, except to the extent that claimants seek punitive damages, which may not be covered by insurance in certain states in which insurance coverage for punitive damages is not permitted. In addition, insurance coverage for all or certain forms of liability has become increasingly costly and may become unavailable or prohibitively expensive in the future. We record accruals for the contingencies discussed in the sections above to the extent that we conclude it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. No estimate of the possible loss or range of loss in excess of amounts accrued, if any, can be made at this time regarding the matters specifically described above because of the inherently unpredictable nature of legal proceedings, which also may be exacerbated by various factors, including: (i) the damages sought in the proceedings are unsubstantiated or indeterminate; (ii) discovery is not complete; (iii) the proceeding is in its early stages; (iv) the matters present legal uncertainties; (v) there are significant facts in dispute; (vi) there are a large number of parties (including where it is uncertain how liability, if any, will be shared among multiple defendants); or (vii) there is a wide range of potential outcomes. The outcome of any current or future litigation or governmental or internal investigations, including the matters described above, cannot be accurately predicted, nor can we predict any resulting judgments, penalties, fines or other sanctions that may be imposed at the discretion of federal or state regulatory authorities or as a result of actions by third parties. Nevertheless, it is reasonably possible that any such outcome of litigation, judgments, penalties, fines or other sanctions could be substantial, and the outcome of these matters may have a material adverse effect on our results of operations, financial position, and cash flows, and may also affect our reputation.