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Note 1 - Description of Business - Mortgage (Details) - Mortgage segment - USD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019
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Business Overview [Abstract] |  |
Private Mortgage Insurance Protects Lenders For Loans Made With Less Than This Maximum Down Payment Percentage | 20.00% |
Private Mortgage Insurance Protects Lenders For Refinancings Made to Home Buyers With Less Than This Maximum Equity-Ownership Percentage | 20.00% |
Direct Primary Mortgage Insurance in Force | $ 246,100.0 | $ 240,600.0
Direct Primary Mortgage Insurance Risk In Force | 60,700.0 | 60,900.0
Credit Risk Transfer Transactions |  |
Business Overview [Abstract] |  |
Direct Primary Mortgage Insurance Risk In Force | $ 392.0 | $ 275.2

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- Definition Business Overview [Abstract] + References No definition available. + Details
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- Definition This element represents the maximum down payment percentage on a home's purchase price that is used to measure the need for private mortgage insurance. + References No definition available. + Details
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- Definition This element represents the maximum equity-ownership percentage on a home's value that is used to measure the need for private mortgage insurance for refinancings. + References No definition available. + Details
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- Definition Risk In Force + References No definition available. + Details
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Balance Type: | credit
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- Definition Amount of participating insurance in force. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 50 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6483535&loc=d3e16392-158451 + Details
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- Details
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Namespace Prefix: |
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- Details
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Namespace Prefix: |
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Period Type: |