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SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - SUPPLEMENTARY NOTES (Details) - USD ($) | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Insurance Subsidiaries |  |  |
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items] |  |  |
Adjusted statutory net income measurement period | 3 years |  |
Adjusted statutory net income dividend payment measurement period | 2 years |  |
Proceeds from contribution from parent | $ 0 | $ 0 | $ 0
Convertible Junior Subordinated Debentures, at 9% per annum, Due 2063 |  |  |
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items] |  |  |
Stated interest rate (in hundredths) | 9.00% |  |
Mortgage Guaranty Insurance Corporation |  |  |
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items] |  |  |
Percentage of statutory policyholders surplus used to determine maximum allowable dividends | 10.00% |  |
Adjusted statutory net income measurement period | 3 years |  |
Adjusted statutory net income dividend payment measurement period | 2 years |  |
Dividends paid to the parent company | $ 390,000,000 | 280,000,000 | $ 220,000,000
Mortgage Guaranty Insurance Corporation | Convertible Junior Subordinated Debentures, at 9% per annum, Due 2063 |  |  |
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items] |  |  |
Investment in holding company debt |  | $ 132,700,000 |

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- Definition The investment in holding company debt at the end of the period. + References No definition available. + Details
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- Definition The percentage of statutory policyholders' surplus, as defined, as of the preceding calendar year end which is used in the determination of the maximum allowable dividends that the insurance subsidiaries may pay in any twelve-month period without regulatory approval by the Office of the Commissioner of Insurance of the State of Wisconsin. + References No definition available. + Details
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- Definition Statutory Accounting Practices, Statutory Amount Available For Dividend Payments Without Regulatory Approval, Measurement, Measurement Period + References No definition available. + Details
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- Definition Statutory Accounting Practices, Statutory Amount Available for Dividend Payments without Regulatory Approval, Measurement, Dividend Payment Period + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition This element represents disclosure of the total aggregate cash dividends paid to the entity by consolidated subsidiaries, by unconsolidated subsidiaries, and by 50% or less owned persons accounted for using the equity method. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04(b)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition The cash inflow from parent as a source of financing that is recorded as additional paid in capital. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585 + Details
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