Litigation and Contingencies	9 Months Ended
Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Litigation and Contingencies	Litigation and Contingencies 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. We call such reduction of claims “curtailments.” In 2015 and the first three quarters of 2016, curtailments reduced our average claim paid by approximately 6.7% and 5.4%, respectively. When reviewing the loan file associated with a claim, we may determine that we have the right to rescind coverage on the loan. (In our SEC reports, we refer to insurance rescissions and denials of claims collectively as “rescissions” and variations of that term.) In recent quarters, approximately 4% of claims received in a quarter have been resolved by rescissions, down from the peak of approximately 28% in the first half of 2009. Our loss reserving methodology incorporates our estimates of future rescissions, curtailments, and reversals of rescissions and curtailments. A variance between ultimate actual rescission, curtailment and reversal rates and our estimates, as a result of the outcome of litigation, settlements or other factors, could materially affect our losses. When the insured disputes our right to curtail claims or rescind coverage, we generally engage in discussions in an attempt to settle the dispute. If we are unable to reach a settlement, the outcome of a dispute ultimately would be determined by legal proceedings. Until a liability associated with settlement discussions or legal proceedings becomes probable and can be reasonably estimated, we consider our claim payment or rescission resolved for financial reporting purposes. Under ASC 450-20, an estimated loss from such discussions and proceedings is accrued for only if we determine that the loss is probable and can be reasonably estimated. In such cases, we have recorded our best estimate of our probable loss. If we are not able to implement settlements we consider probable, we intend to defend MGIC vigorously against any related legal proceedings. In addition to matters for which we have recorded a probable loss, we are involved in other discussions and/or proceedings with insureds with respect to our claims paying practices. Although it is reasonably possible that when these matters are resolved we will not prevail in all cases, we are unable to make a reasonable estimate or range of estimates of the potential liability. We estimate the maximum exposure associated with matters where a loss is reasonably possible to be approximately $281 million, although we believe (but can give no assurance that) we will ultimately resolve these matters for significantly less than this amount. This estimate of our maximum exposure does not include interest or consequential or exemplary damages. Mortgage insurers, including MGIC, have been involved in litigation and regulatory actions related to alleged 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. For MGIC, while these proceedings in the aggregate have not resulted in material liability, were there to be future proceedings under these laws, there can be no assurance that the outcome would not have a material adverse effect on us. In addition, various regulators, including the CFPB, state insurance commissioners and state attorneys general may bring other actions seeking various forms of relief in connection with alleged 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. 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. Claims for remedies may be made a number of years after the underwriting work was performed. Beginning in the second half of 2009, our subsidiary experienced an increase in claims for contract underwriting remedies, which continued throughout 2012. The underwriting remedy expense for 2015 was approximately $1 million, but may increase in the future. 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. See Note 11 – “Income Taxes” for a description of federal income tax contingencies.

Litigation and Contingencies

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. We call such reduction of claims “curtailments.” In 2015 and the first three quarters of 2016, curtailments reduced our average claim paid by approximately 6.7% and 5.4%, respectively.

When reviewing the loan file associated with a claim, we may determine that we have the right to rescind coverage on the loan. (In our SEC reports, we refer to insurance rescissions and denials of claims collectively as “rescissions” and variations of that term.) In recent quarters, approximately 4% of claims received in a quarter have been resolved by rescissions, down from the peak of approximately 28% in the first half of 2009. Our loss reserving methodology incorporates our estimates of future rescissions, curtailments, and reversals of rescissions and curtailments. A variance between ultimate actual rescission, curtailment and reversal rates and our estimates, as a result of the outcome of litigation, settlements or other factors, could materially affect our losses.

When the insured disputes our right to curtail claims or rescind coverage, we generally engage in discussions in an attempt to settle the dispute. If we are unable to reach a settlement, the outcome of a dispute ultimately would be determined by legal proceedings.

Until a liability associated with settlement discussions or legal proceedings becomes probable and can be reasonably estimated, we consider our claim payment or rescission resolved for financial reporting purposes. Under ASC 450-20, an estimated loss from such discussions and proceedings is accrued for only if we determine that the loss is probable and can be reasonably estimated. In such cases, we have recorded our best estimate of our probable loss. If we are not able to implement settlements we consider probable, we intend to defend MGIC vigorously against any related legal proceedings.

In addition to matters for which we have recorded a probable loss, we are involved in other discussions and/or proceedings with insureds with respect to our claims paying practices. Although it is reasonably possible that when these matters are resolved we will not prevail in all cases, we are unable to make a reasonable estimate or range of estimates of the potential liability. We estimate the maximum exposure associated with matters where a loss is reasonably possible to be approximately $281 million, although we believe (but can give no assurance that) we will ultimately resolve these matters for significantly less than this amount. This estimate of our maximum exposure does not include interest or consequential or exemplary damages.

Mortgage insurers, including MGIC, have been involved in litigation and regulatory actions related to alleged 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.

For MGIC, while these proceedings in the aggregate have not resulted in material liability, were there to be future proceedings under these laws, there can be no assurance that the outcome would not have a material adverse effect on us. In addition, various regulators, including the CFPB, state insurance commissioners and state attorneys general may bring other actions seeking various forms of relief in connection with alleged 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.

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. Claims for remedies may be made a number of years after the underwriting work was performed. Beginning in the second half of 2009, our subsidiary experienced an increase in claims for contract underwriting remedies, which continued throughout 2012. The underwriting remedy expense for 2015 was approximately $1 million, but may increase in the future.

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.

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