Litigation and Contingencies	3 Months Ended
Mar. 31, 2013
Litigation and Contingencies [Abstract]
Litigation and Contingencies	Note 5 – Litigation and Contingencies Consumers continue to bring lawsuits against home mortgage lenders and settlement service providers. Mortgage insurers, including MGIC, have been involved in litigation alleging violations of the anti-referral fee provisions of the Real Estate Settlement Procedures Act, which is commonly known as RESPA, and the notice provisions of the Fair Credit Reporting Act, which is commonly known as FCRA. MGIC's settlement of class action litigation against it under RESPA became final in October 2003. MGIC settled the named plaintiffs' claims in litigation against it under FCRA in December 2004, following denial of class certification in June 2004. Since December 2006, class action litigation has been brought against a number of large lenders alleging that their captive mortgage reinsurance arrangements violated RESPA. Beginning in December 2011, MGIC, together with various mortgage lenders and other mortgage insurers, have been named as defendants in twelve lawsuits, alleged to be class actions, filed in various U.S. District Courts. Four of those cases have previously been dismissed. The complaints in all eight of the remaining cases allege various causes of action related to the captive mortgage reinsurance arrangements of the mortgage lenders, including that the defendants violated RESPA by paying excessive premiums to the lenders' captive reinsurer in relation to the risk assumed by that captive. MGIC denies any wrongdoing and intends to vigorously defend itself against the allegations in the lawsuits. There can be no assurance that we will not be subject to further litigation under RESPA (or FCRA) or that the outcome of any such litigation, including the lawsuits mentioned above, would not have a material adverse effect on us. See Note 4 - "Reinsurance" for a discussion of MGIC's recent settlement with the CFPB. In connection with the settlement, MGIC paid a civil penalty of $2.65 million. We remain subject to various state investigations or information requests regarding captive mortgage reinsurance arrangements, including (1) a request received by MGIC in June 2005 from the New York Department of Financial Services for information regarding captive mortgage reinsurance arrangements and other types of arrangements in which lenders receive compensation; and (2) requests received from the Minnesota Department of Commerce beginning in February 2006 regarding captive mortgage reinsurance and certain other matters in response to which MGIC has provided information on several occasions, including as recently as May 2011. Other insurance departments or other officials, including attorneys general, may also seek information about or investigate captive mortgage reinsurance. Various regulators, including the CFPB, state insurance commissioners and state attorneys general may bring actions seeking various forms of relief, including civil penalties and injunctions against violations of RESPA. The insurance law provisions of many states prohibit paying for the referral of insurance business and provide various mechanisms to enforce this prohibition. While we believe our practices are in conformity with applicable laws and regulations, it is not possible to predict the eventual scope, duration or outcome of any such reviews or investigations nor is it possible to predict their effect on us or the mortgage insurance industry. We are subject to comprehensive, detailed regulation by state insurance departments. These regulations are principally designed for the protection of our insured policyholders, rather than for the benefit of investors. Although their scope varies, state insurance laws generally grant broad supervisory powers to agencies or officials to examine insurance companies and enforce rules or exercise discretion affecting almost every significant aspect of the insurance business. Given the recent significant losses incurred by many insurers in the mortgage and financial guaranty industries, our insurance subsidiaries have been subject to heightened scrutiny by insurance regulators. State insurance regulatory authorities could take actions, including changes in capital requirements or termination of waivers of capital requirements, that could have a material adverse effect on us. In January 2013, the CFPB issued rules to implement laws requiring mortgage lenders to make ability-to-pay determinations prior to extending credit. We are uncertain whether the CFPB will issue any other rules or regulations that affect our business apart from any action it may take as a result of its investigation of captive mortgage reinsurance. Such rules and regulations could have a material adverse effect on us. We understand several law firms have, among other things, issued press releases to the effect that they are investigating us, including whether the fiduciaries of our 401(k) plan breached their fiduciary duties regarding the plan's investment in or holding of our common stock or whether we breached other legal or fiduciary obligations to our shareholders. We intend to defend vigorously any proceedings that may result from these investigations. With limited exceptions, our bylaws provide that our officers and 401(k) plan fiduciaries are entitled to indemnification from us for claims against them. Since December 2009, we have been involved in legal proceedings with Countrywide Home Loans ("CHL") and its affiliate, Bank of America, N.A., as successor to Countrywide Home Loans Servicing LP ("BANA") and collectively with CHL, "Countrywide") in which Countrywide alleged that MGIC denied valid mortgage insurance claims. (In our SEC reports, we refer to rescissions of insurance and denials of claims collectively as "rescissions" and variations of that term.) In addition to the claim amounts it alleged MGIC had improperly denied, Countrywide contended it was entitled to other damages of almost $700 million as well as exemplary damages. We sought a determination in those proceedings that we were entitled to rescind coverage on the applicable loans. From January 1, 2008 through March 31, 2013, rescissions of coverage on Countrywide-related loans mitigated our paid losses on the order of $445 million. This amount is the amount we estimate we would have paid had the coverage not been rescinded. In addition, in connection with mediation we were holding with Countrywide, we voluntarily suspended rescissions related to loans that we believed could be covered by a settlement. As of March 31, 2013, coverage on approximately 2,300 loans, representing total potential claim payments of approximately $170 million, that we had determined was rescindable, was affected by our decision to suspend such rescissions. In April 2013, MGIC entered into separate settlement agreements with CHL and BANA, pursuant to which the parties will settle the Countrywide litigation as it relates to MGIC's rescission practices. The agreement with BANA covers loans which had been sold to the GSEs by CHL, including loans subsequently repurchased by BANA, as well as other CHL-originated loans currently owned by BANA or one of its affiliates. Implementation of the BANA Agreement is subject to consent and approval by both GSEs. The agreement with CHL covers loans which were purchased by non-GSE investors, including securitization trusts (the "other investors"). The CHL Agreement will not be implemented until the implementation of the BANA Agreement and then will be implemented only as and to the extent that it is approved by or on behalf of the other investors. While there can be no assurance that the Agreements will be implemented, we have determined that their implementation is probable. Under the Agreements, the parties are seeking to stay their pending arbitration proceedings. Upon implementation of the BANA Agreement, the pending arbitration proceedings concerning the loans covered by the BANA Agreement will be dismissed, and the parties will provide mutual releases. Upon obtaining a specified number of consents by or on behalf of the other investors and also upon the conclusion of the period in the CHL Agreement for obtaining consents by or on behalf of the other investors, all legal proceedings will be dismissed and the parties will provide mutual releases, in each case limited as to the loans held by the other investors that consent to the CHL Agreement. We are also discussing a settlement of a dispute with another customer and have also determined that it is probable we will reach a settlement with this customer. As of March 31, 2013, coverage on approximately 300 loans, representing total potential claim payments of approximately $20 million, was affected by our decision to suspend rescissions for that customer. We recorded the estimated impact of the two probable settlements referred to above in our financial statements for the quarter ending December 31, 2012. The aggregate impact to loss reserves for the probable settlement agreements was an increase of approximately $100 million. This impact was somewhat offset by impacts to our return premium accrual and premium deficiency reserve. There was no additional charge in the first quarter of 2013 as a result of executing these agreements, as the financial impact was in line with our original estimations. If we are not able to implement the Agreements, we intend to defend MGIC against any related legal proceedings, vigorously. The flow policies at issue with Countrywide are in the same form as the flow policies that we use with all of our customers, and the bulk policies at issue vary from one another, but are generally similar to those used in the majority of our Wall Street bulk transactions. The settlement with Countrywide may encourage other customers to pursue remedies against us. From January 1, 2008 through March 31, 2013, we estimate that total rescissions mitigated our incurred losses by approximately $2.9 billion, which included approximately $2.9 billion of mitigation on paid losses, excluding $0.6 billion that would have been applied to a deductible. At March 31, 2013, we estimate that our total loss reserves were benefited from anticipated rescissions by approximately $0.2 billion. Before paying a claim, we review the loan and servicing files to determine the appropriateness of the claim amount. All of our insurance policies provide that we can reduce or deny a claim if the servicer did not comply with its obligations under our insurance policy, including the requirement to mitigate our loss by performing reasonable loss mitigation efforts or, for example, diligently pursuing a foreclosure or bankruptcy relief in a timely manner. We call such reduction of claims submitted to us "curtailments." In 2012 and the first quarter of 2013, curtailments reduced our average claim paid by approximately 4.1% and 4.7%, respectively. In addition, the claims submitted to us sometimes include costs and expenses not covered by our insurance policies, such as mortgage insurance premiums, hazard insurance premiums for periods after the claim date and losses resulting from property damage that has not been repaired. These other adjustments reduced claim amounts by less than the amount of curtailments. After we pay a claim, servicers and insureds sometimes object to our curtailments and other adjustments. We review these objections if they are sent to us within 90 days after the claim was paid. Historically, we have not had material disputes regarding our curtailments or other adjustments. The Agreements referred to above do not resolve assertions by Countrywide that MGIC has improperly curtailed numerous insurance coverage claims. Countrywide has asserted that the amount of disputed curtailments approximates $40 million. MGIC and Countrywide have agreed to mediate this matter and to enter into arbitration if the mediation does not resolve the matter. We do not believe a loss is probable regarding this curtailment dispute and have not accrued any reserves that would reflect an adverse outcome to this dispute. We intend to defend vigorously our position regarding the correctness of these curtailments under our insurance policy. Although we have not had other material objections to our curtailment and adjustment practices, there can be no assurances that we will not face additional challenges to such practices. A non-insurance subsidiary of our holding company is a shareholder of the corporation that operates the Mortgage Electronic Registration System ("MERS"). Our subsidiary, as a shareholder of MERS, has been named as a defendant (along with MERS and its other shareholders) in eight lawsuits asserting various causes of action arising from allegedly improper recording and foreclosure activities by MERS. Two of those lawsuits remain pending and the other six lawsuits have been dismissed without any further opportunity to appeal. The damages sought in the remaining cases are substantial. We deny any wrongdoing and intend to defend ourselves against the allegations in the lawsuits, vigorously. In addition to the matters described above, we are involved in other legal proceedings in the ordinary course of business. In our opinion, based on the facts known at this time, the ultimate resolution of these ordinary course legal proceedings will not have a material adverse effect on our financial position or results of operations. Through a non-insurance subsidiary, we utilize our underwriting skills to provide an outsourced underwriting service to our customers known as contract underwriting. As part of the contract underwriting activities, that subsidiary is responsible for the quality of the underwriting decisions in accordance with the terms of the contract underwriting agreements with customers. That subsidiary may be required to provide certain remedies to its customers if certain standards relating to the quality of our underwriting work are not met, and we have an established reserve for such future obligations. These obligations have been primarily funded by contributions from our holding company and, in part, from the operations of the subsidiary. A generally positive economic environment for residential real estate that continued until approximately 2007 may have mitigated the effect of some of these costs in previous years. Historically, a material portion of our new insurance written through the flow channel has involved loans for which that subsidiary provided contract underwriting services, including new insurance written between 2006 and 2008. Claims for remedies may be made a number of years after the underwriting work was performed. We believe the rescission of mortgage insurance coverage on loans for which the subsidiary provided contract underwriting services may make a claim for a contract underwriting remedy more likely to occur. Beginning in the second half of 2009, our subsidiary experienced an increase in claims for contract underwriting remedies, which continued throughout 2012. The related contract underwriting remedy expense was approximately $27 million, $23 million and $19 million for the years ended December 31, 2012, 2011 and 2010. The underwriting remedy expense for each of the first three months of 2013 and 2012 was not significant. See Note 11 – "Income Taxes" for a description of federal income tax contingencies.

Note 5 – Litigation and Contingencies

Consumers continue to bring lawsuits against home mortgage lenders and settlement service providers. Mortgage insurers, including MGIC, have been involved in litigation alleging violations of the anti-referral fee provisions of the Real Estate Settlement Procedures Act, which is commonly known as RESPA, and the notice provisions of the Fair Credit Reporting Act, which is commonly known as FCRA. MGIC's settlement of class action litigation against it under RESPA became final in October 2003. MGIC settled the named plaintiffs' claims in litigation against it under FCRA in December 2004, following denial of class certification in June 2004. Since December 2006, class action litigation has been brought against a number of large lenders alleging that their captive mortgage reinsurance arrangements violated RESPA. Beginning in December 2011, MGIC, together with various mortgage lenders and other mortgage insurers, have been named as defendants in twelve lawsuits, alleged to be class actions, filed in various U.S. District Courts. Four of those cases have previously been dismissed. The complaints in all eight of the remaining cases allege various causes of action related to the captive mortgage reinsurance arrangements of the mortgage lenders, including that the defendants violated RESPA by paying excessive premiums to the lenders' captive reinsurer in relation to the risk assumed by that captive. MGIC denies any wrongdoing and intends to vigorously defend itself against the allegations in the lawsuits. There can be no assurance that we will not be subject to further litigation under RESPA (or FCRA) or that the outcome of any such litigation, including the lawsuits mentioned above, would not have a material adverse effect on us.

See Note 4 - "Reinsurance" for a discussion of MGIC's recent settlement with the CFPB. In connection with the settlement, MGIC paid a civil penalty of $2.65 million.

We remain subject to various state investigations or information requests regarding captive mortgage reinsurance arrangements, including (1) a request received by MGIC in June 2005 from the New York Department of Financial Services for information regarding captive mortgage reinsurance arrangements and other types of arrangements in which lenders receive compensation; and (2) requests received from the Minnesota Department of Commerce beginning in February 2006 regarding captive mortgage reinsurance and certain other matters in response to which MGIC has provided information on several occasions, including as recently as May 2011. Other insurance departments or other officials, including attorneys general, may also seek information about or investigate captive mortgage reinsurance.

Various regulators, including the CFPB, state insurance commissioners and state attorneys general may bring actions seeking various forms of relief, including civil penalties and injunctions against violations of RESPA. The insurance law provisions of many states prohibit paying for the referral of insurance business and provide various mechanisms to enforce this prohibition. While we believe our practices are in conformity with applicable laws and regulations, it is not possible to predict the eventual scope, duration or outcome of any such reviews or investigations nor is it possible to predict their effect on us or the mortgage insurance industry.

We are subject to comprehensive, detailed regulation by state insurance departments. These regulations are principally designed for the protection of our insured policyholders, rather than for the benefit of investors. Although their scope varies, state insurance laws generally grant broad supervisory powers to agencies or officials to examine insurance companies and enforce rules or exercise discretion affecting almost every significant aspect of the insurance business. Given the recent significant losses incurred by many insurers in the mortgage and financial guaranty industries, our insurance subsidiaries have been subject to heightened scrutiny by insurance regulators. State insurance regulatory authorities could take actions, including changes in capital requirements or termination of waivers of capital requirements, that could have a material adverse effect on us. In January 2013, the CFPB issued rules to implement laws requiring mortgage lenders to make ability-to-pay determinations prior to extending credit. We are uncertain whether the CFPB will issue any other rules or regulations that affect our business apart from any action it may take as a result of its investigation of captive mortgage reinsurance. Such rules and regulations could have a material adverse effect on us.

We understand several law firms have, among other things, issued press releases to the effect that they are investigating us, including whether the fiduciaries of our 401(k) plan breached their fiduciary duties regarding the plan's investment in or holding of our common stock or whether we breached other legal or fiduciary obligations to our shareholders. We intend to defend vigorously any proceedings that may result from these investigations. With limited exceptions, our bylaws provide that our officers and 401(k) plan fiduciaries are entitled to indemnification from us for claims against them.

Since December 2009, we have been involved in legal proceedings with Countrywide Home Loans ("CHL") and its affiliate, Bank of America, N.A., as successor to Countrywide Home Loans Servicing LP ("BANA") and collectively with CHL, "Countrywide") in which Countrywide alleged that MGIC denied valid mortgage insurance claims. (In our SEC reports, we refer to rescissions of insurance and denials of claims collectively as "rescissions" and variations of that term.) In addition to the claim amounts it alleged MGIC had improperly denied, Countrywide contended it was entitled to other damages of almost $700 million as well as exemplary damages. We sought a determination in those proceedings that we were entitled to rescind coverage on the applicable loans. From January 1, 2008 through March 31, 2013, rescissions of coverage on Countrywide-related loans mitigated our paid losses on the order of $445 million. This amount is the amount we estimate we would have paid had the coverage not been rescinded. In addition, in connection with mediation we were holding with Countrywide, we voluntarily suspended rescissions related to loans that we believed could be covered by a settlement. As of March 31, 2013, coverage on approximately 2,300 loans, representing total potential claim payments of approximately $170 million, that we had determined was rescindable, was affected by our decision to suspend such rescissions.

In April 2013, MGIC entered into separate settlement agreements with CHL and BANA, pursuant to which the parties will settle the Countrywide litigation as it relates to MGIC's rescission practices.

The agreement with BANA covers loans which had been sold to the GSEs by CHL, including loans subsequently repurchased by BANA, as well as other CHL-originated loans currently owned by BANA or one of its affiliates. Implementation of the BANA Agreement is subject to consent and approval by both GSEs. The agreement with CHL covers loans which were purchased by non-GSE investors, including securitization trusts (the "other investors"). The CHL Agreement will not be implemented until the implementation of the BANA Agreement and then will be implemented only as and to the extent that it is approved by or on behalf of the other investors. While there can be no assurance that the Agreements will be implemented, we have determined that their implementation is probable.

Under the Agreements, the parties are seeking to stay their pending arbitration proceedings. Upon implementation of the BANA Agreement, the pending arbitration proceedings concerning the loans covered by the BANA Agreement will be dismissed, and the parties will provide mutual releases. Upon obtaining a specified number of consents by or on behalf of the other investors and also upon the conclusion of the period in the CHL Agreement for obtaining consents by or on behalf of the other investors, all legal proceedings will be dismissed and the parties will provide mutual releases, in each case limited as to the loans held by the other investors that consent to the CHL Agreement.

We are also discussing a settlement of a dispute with another customer and have also determined that it is probable we will reach a settlement with this customer. As of March 31, 2013, coverage on approximately 300 loans, representing total potential claim payments of approximately $20 million, was affected by our decision to suspend rescissions for that customer.

We recorded the estimated impact of the two probable settlements referred to above in our financial statements for the quarter ending December 31, 2012. The aggregate impact to loss reserves for the probable settlement agreements was an increase of approximately $100 million. This impact was somewhat offset by impacts to our return premium accrual and premium deficiency reserve. There was no additional charge in the first quarter of 2013 as a result of executing these agreements, as the financial impact was in line with our original estimations. If we are not able to implement the Agreements, we intend to defend MGIC against any related legal proceedings, vigorously.

The flow policies at issue with Countrywide are in the same form as the flow policies that we use with all of our customers, and the bulk policies at issue vary from one another, but are generally similar to those used in the majority of our Wall Street bulk transactions. The settlement with Countrywide may encourage other customers to pursue remedies against us. From January 1, 2008 through March 31, 2013, we estimate that total rescissions mitigated our incurred losses by approximately $2.9 billion, which included approximately $2.9 billion of mitigation on paid losses, excluding $0.6 billion that would have been applied to a deductible. At March 31, 2013, we estimate that our total loss reserves were benefited from anticipated rescissions by approximately $0.2 billion.

Before paying a claim, we review the loan and servicing files to determine the appropriateness of the claim amount. All of our insurance policies provide that we can reduce or deny a claim if the servicer did not comply with its obligations under our insurance policy, including the requirement to mitigate our loss by performing reasonable loss mitigation efforts or, for example, diligently pursuing a foreclosure or bankruptcy relief in a timely manner. We call such reduction of claims submitted to us "curtailments." In 2012 and the first quarter of 2013, curtailments reduced our average claim paid by approximately 4.1% and 4.7%, respectively. In addition, the claims submitted to us sometimes include costs and expenses not covered by our insurance policies, such as mortgage insurance premiums, hazard insurance premiums for periods after the claim date and losses resulting from property damage that has not been repaired. These other adjustments reduced claim amounts by less than the amount of curtailments.

After we pay a claim, servicers and insureds sometimes object to our curtailments and other adjustments. We review these objections if they are sent to us within 90 days after the claim was paid. Historically, we have not had material disputes regarding our curtailments or other adjustments.

The Agreements referred to above do not resolve assertions by Countrywide that MGIC has improperly curtailed numerous insurance coverage claims. Countrywide has asserted that the amount of disputed curtailments approximates $40 million. MGIC and Countrywide have agreed to mediate this matter and to enter into arbitration if the mediation does not resolve the matter. We do not believe a loss is probable regarding this curtailment dispute and have not accrued any reserves that would reflect an adverse outcome to this dispute. We intend to defend vigorously our position regarding the correctness of these curtailments under our insurance policy. Although we have not had other material objections to our curtailment and adjustment practices, there can be no assurances that we will not face additional challenges to such practices.

A non-insurance subsidiary of our holding company is a shareholder of the corporation that operates the Mortgage Electronic Registration System ("MERS"). Our subsidiary, as a shareholder of MERS, has been named as a defendant (along with MERS and its other shareholders) in eight lawsuits asserting various causes of action arising from allegedly improper recording and foreclosure activities by MERS. Two of those lawsuits remain pending and the other six lawsuits have been dismissed without any further opportunity to appeal. The damages sought in the remaining cases are substantial. We deny any wrongdoing and intend to defend ourselves against the allegations in the lawsuits, vigorously.

In addition to the matters described above, we are involved in other legal proceedings in the ordinary course of business. In our opinion, based on the facts known at this time, the ultimate resolution of these ordinary course legal proceedings will not have a material adverse effect on our financial position or results of operations.

Through a non-insurance subsidiary, we utilize our underwriting skills to provide an outsourced underwriting service to our customers known as contract underwriting. As part of the contract underwriting activities, that subsidiary is responsible for the quality of the underwriting decisions in accordance with the terms of the contract underwriting agreements with customers. That subsidiary may be required to provide certain remedies to its customers if certain standards relating to the quality of our underwriting work are not met, and we have an established reserve for such future obligations. These obligations have been primarily funded by contributions from our holding company and, in part, from the operations of the subsidiary. A generally positive economic environment for residential real estate that continued until approximately 2007 may have mitigated the effect of some of these costs in previous years. Historically, a material portion of our new insurance written through the flow channel has involved loans for which that subsidiary provided contract underwriting services, including new insurance written between 2006 and 2008. Claims for remedies may be made a number of years after the underwriting work was performed. We believe the rescission of mortgage insurance coverage on loans for which the subsidiary provided contract underwriting services may make a claim for a contract underwriting remedy more likely to occur. Beginning in the second half of 2009, our subsidiary experienced an increase in claims for contract underwriting remedies, which continued throughout 2012. The related contract underwriting remedy expense was approximately $27 million, $23 million and $19 million for the years ended December 31, 2012, 2011 and 2010. The underwriting remedy expense for each of the first three months of 2013 and 2012 was not significant.

See Note 11 – "Income Taxes" for a description of federal income tax contingencies.