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Nature of Business | 12 Months Ended
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Dec. 31, 2021
Nature of Business [Abstract] |
Nature of Business |
NOTE 1 |  | Nature of Business
MGIC Investment Corporation is a holding company which, through Mortgage Guaranty Insurance Corporation ("MGIC"), is principally engaged in the mortgage insurance business. We provide mortgage insurance to lenders throughout the United States and to government sponsored entities to protect against loss from defaults on low down payment residential mortgage loans. Primary mortgage insurance provides mortgage default protection on individual loans and covers a percentage of the unpaid loan principal, delinquent interest and certain expenses associated with the default and subsequent foreclosure or sale approved by us, of the underlying property. MGIC Assurance Corporation ("MAC") and MGIC Indemnity Corporation ("MIC"), insurance subsidiaries of MGIC, provide insurance for certain mortgages under Fannie Mae and Freddie Mac (the "GSEs") credit risk transfer programs. Through certain non-insurance subsidiaries, we also provide certain services for the mortgage finance industry, such as contract underwriting. At December 31, 2021, our direct primary insurance in force ("IIF") was $274.4 billion, which represents the principal balance in our records of all mortgage loans that we insure, and our direct primary risk in force ("RIF") was $69.3 billion, which represents the IIF multiplied by the insurance coverage percentage. The substantial majority of our NIW has been for loans purchased by the GSEs. The current private mortgage insurer eligibility requirements ("PMIERs") of the GSEs include financial requirements, as well as business, quality control and certain transactional approval requirements. The financial requirements of the PMIERs require a mortgage insurer’s "Available Assets" (generally only the most liquid assets of an insurer) to equal or exceed its "Minimum Required Assets" (which are based on an insurer's book of risk in force, calculated from tables of factors with several risk dimensions). Based on our application of the PMIERs, as of December 31, 2021, MGIC’s Available Assets are in excess of its Minimum Required Assets; and MGIC is in compliance with the PMIERs and eligible to insure loans purchased by the GSEs.

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- Definition The entire disclosure for the nature of an entity's business, major products or services, principal markets including location, and the relative importance of its operations in each business and the basis for the determination, including but not limited to, assets, revenues, or earnings. For an entity that has not commenced principal operations, disclosures about the risks and uncertainties related to the activities in which the entity is currently engaged and an understanding of what those activities are being directed toward. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e5967-108592 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -URI http://asc.fasb.org/topic&trid=2134479 + Details
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