XML 52 R41.htm IDEA: XBRL DOCUMENT
v3.23.2

Reinsurance - Excess of Loss Reinsurance (Details) - USD ($) $ in Thousands |  |  |  |  |  |  |  |  | 6 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Apr. 01, 2023 | Apr. 26, 2022 | Apr. 01, 2022 | Aug. 03, 2021 | Feb. 02, 2021 | Oct. 29, 2020 | May 25, 2019 | Oct. 30, 2018 | Jun. 30, 2023 | Dec. 31, 2022
2023 Traditional XOL |  |  |  |  |  |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |  |  |  |  |  |
Amortization period excess of loss reinsurance coverage | 10 years |  |  |  |  |  |  |  |  |
Excess of loss reinsurance coverage, initial and remaining | $ 116,000 |  |  |  |  |  |  |  |  |
2022 Traditional XOL |  |  |  |  |  |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |  |  |  |  |  |
Amortization period excess of loss reinsurance coverage |  |  | 10 years |  |  |  |  |  |  |
Initial first layer retention |  |  | $ 82,523 |  |  |  |  |  |  |
Remaining first layer retention |  |  |  |  |  |  |  |  | $ 82,490 | $ 82,517
Excess of loss reinsurance coverage, initial and remaining |  |  | $ 142,642 |  |  |  |  |  | 142,642 | 142,642
Home Re 2022-1 |  |  |  |  |  |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |  |  |  |  |  |
Term of mortgage insurance-linked notes |  | 12 years 6 months |  |  |  |  |  |  |  |
Initial first layer retention |  | $ 325,589 |  |  |  |  |  |  |  |
Remaining first layer retention |  |  |  |  |  |  |  |  | 325,317 | 325,576
Excess of loss reinsurance coverage, initial and remaining |  | $ 473,575 |  |  |  |  |  |  | 473,575 | 473,575
Home Re 2021-2 |  |  |  |  |  |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |  |  |  |  |  |
Term of mortgage insurance-linked notes |  |  |  | 12 years 6 months |  |  |  |  |  |
Initial first layer retention |  |  |  | $ 190,159 |  |  |  |  |  |
Remaining first layer retention |  |  |  |  |  |  |  |  | 189,894 | 190,097
Excess of loss reinsurance coverage, initial and remaining |  |  |  | $ 398,429 |  |  |  |  | 299,100 | 352,084
Home Re 2021-1 |  |  |  |  |  |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |  |  |  |  |  |
Term of mortgage insurance-linked notes |  |  |  |  | 12 years 6 months |  |  |  |  |
Initial first layer retention |  |  |  |  | $ 211,159 |  |  |  |  |
Remaining first layer retention |  |  |  |  |  |  |  |  | 210,961 | 211,102
Excess of loss reinsurance coverage, initial and remaining |  |  |  |  | $ 398,848 |  |  |  | 229,325 | 277,053
Home Re 2020-1 |  |  |  |  |  |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |  |  |  |  |  |
Term of mortgage insurance-linked notes |  |  |  |  |  | 10 years |  |  |  |
Initial first layer retention |  |  |  |  |  | $ 275,283 |  |  |  |
Remaining first layer retention |  |  |  |  |  |  |  |  | 274,978 | 275,051
Excess of loss reinsurance coverage, initial and remaining |  |  |  |  |  | $ 412,917 |  |  | 72,127 | 113,247
Home Re 2019-1 |  |  |  |  |  |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |  |  |  |  |  |
Term of mortgage insurance-linked notes |  |  |  |  |  |  | 10 years |  |  |
Initial first layer retention |  |  |  |  |  |  | $ 185,730 |  |  |
Remaining first layer retention |  |  |  |  |  |  |  |  | 183,000 | 183,540
Excess of loss reinsurance coverage, initial and remaining |  |  |  |  |  |  | $ 315,739 |  | 208,146 | 208,146
Home Re 2018-1 |  |  |  |  |  |  |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |  |  |  |  |  |  |
Term of mortgage insurance-linked notes |  |  |  |  |  |  |  | 10 years |  |
Initial first layer retention |  |  |  |  |  |  |  | $ 168,691 |  |
Remaining first layer retention |  |  |  |  |  |  |  |  | 164,572 | 164,849
Excess of loss reinsurance coverage, initial and remaining |  |  |  |  |  |  |  | $ 318,636 | $ 102,557 | $ 140,993

X
- Definition Amortization Period Excess of Loss Reinsurance Coverage + References No definition available. + Details
Name: | mtg_AmortizationPeriodExcessofLossReinsuranceCoverage
Namespace Prefix: | mtg_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Reinsurance Retention Policy, Debt Issued To Cover Insurance, Term + References No definition available. + Details
Name: | mtg_ReinsuranceRetentionPolicyDebtIssuedToCoverInsuranceTerm
Namespace Prefix: | mtg_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Reinsurance Retention Policy, Excess of Loss Reinsurance Coverages + References No definition available. + Details
Name: | mtg_ReinsuranceRetentionPolicyExcessOfLossReinsuranceCoverages
Namespace Prefix: | mtg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Reinsurance Retention Policy, Initial Amount Retained + References No definition available. + Details
Name: | mtg_ReinsuranceRetentionPolicyInitialAmountRetained
Namespace Prefix: | mtg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- 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
Name: | us-gaap_EffectsOfReinsuranceLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount per life of risk undertaken originally by insurer that is not ceded to reinsurer. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479838/944-20-50-3 + Details
Name: | us-gaap_ReinsuranceRetentionAmountRetainedPerLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=mtg_A2023TraditionalXOLMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=mtg_A2022TraditionalXOLMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=mtg_HomeRe20221Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=mtg_HomeRe20212Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=mtg_HomeRe20211Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=mtg_HomeRe20201Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=mtg_HomeRe20191Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=mtg_HomeRe20181Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |