XML 67 R53.htm IDEA: XBRL DOCUMENT
v3.20.2

Loss Reserves (Details) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2020 USD ($) loan | Sep. 30, 2019 loan | Sep. 30, 2020 USD ($) loan | Sep. 30, 2019 USD ($) loan | Dec. 31, 2019 USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |
Prior years | $ |  |  | $ 17,317 | $ (47,760) |
Prior years | $ |  |  | $ 93,937 | $ 165,844 |
Percentage of prior year default inventory resolved |  |  | 61.00% | 61.00% |
Premium refund liability, expected claim payments | $ | $ 29,000 |  | $ 29,000 |  | $ 30,000
Primary Delinquent Inventory [Roll Forward] |  |  |  |  |
Delinquent inventory at the beginning of period (in loans) | loan | 69,326 | 29,795 | 30,028 | 32,898 |
New notices (in loans) | loan | 20,924 | 14,019 | 90,906 | 40,545 |
Cures (in loans) | loan | (25,446) | (12,592) | (54,523) | (39,822) |
Paids (including those charged to a deductible or captive) (in loans) | loan | (375) | (1,045) | (1,933) | (3,345) |
Rescissions and denials (in loans) | loan | (11) | (42) | (60) | (141) |
Other items removed from inventory (in loans) | loan | 0 | (195) | 0 | (195) |
Delinquent inventory at end of period (in loans) | loan | 64,418 | 29,940 | 64,418 | 29,940 |
Probable loss on litigation claims paying practices |  |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |
Prior years | $ |  |  |  | $ 23,500 |
Decrease in estimated claim rate on primary defaults |  |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |
Prior years | $ |  |  | $ (1,626) | (94,294) |
Increase in estimated severity on primary defaults |  |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |
Prior years | $ |  |  | 13,503 | 2,637 |
Change in estimates related to pool reserves, LAE reserves, reinsurance, and other |  |  |  |  |
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |
Prior years | $ |  |  | $ 5,440 | $ 43,897 |

X
- Definition The percentage of the prior year default inventory resolved, which is used in the calculation of the change in the severity and claim rates. + References No definition available. + Details
Name: | mtg_PercentageOfPriorYearDefaultInventoryResolved
Namespace Prefix: | mtg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The carrying amount for the estimate of premiums to be refunded on expected claim payments. + References No definition available. + Details
Name: | mtg_PremiumRefundLiabilityExpectedClaimPayments
Namespace Prefix: | mtg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The number of loans in the primary default inventory. + References No definition available. + Details
Name: | mtg_PrimaryDefaultInventory
Namespace Prefix: | mtg_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Deductions from the primary default inventory resulting from loans in default being brought current. + References No definition available. + Details
Name: | mtg_PrimaryDefaultInventoryCures
Namespace Prefix: | mtg_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Additions to the primary default inventory resulting from new notices of defaulted loans. + References No definition available. + Details
Name: | mtg_PrimaryDefaultInventoryNewNotices
Namespace Prefix: | mtg_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Other deductions from the primary default inventory, including items removed for settlements + References No definition available. + Details
Name: | mtg_PrimaryDefaultInventoryOtherItemsRemoved
Namespace Prefix: | mtg_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Deductions from the primary default inventory resulting from claims being paid, including those charged to a deductible or captive. + References No definition available. + Details
Name: | mtg_PrimaryDefaultInventoryPaids
Namespace Prefix: | mtg_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Deductions from the primary default inventory resulting from rescissions and denials. + References No definition available. + Details
Name: | mtg_PrimaryDefaultInventoryRescissionsAndDenials
Namespace Prefix: | mtg_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | mtg_PrimaryDefaultInventoryRollForward
Namespace Prefix: | mtg_
Data Type: | xbrli:stringItemType
Balance Type: | na
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_CausesOfIncreaseDecreaseInLiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after effects of reinsurance, of payments to settle claims incurred in prior periods and related claims settlement costs. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437 + Details
Name: | us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred in prior reporting periods and related claims settlement costs. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437 + Details
Name: | us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_NoncatastrophicEventAxis=mtg_ProbableLossOnLitigationClaimsPayingPracticesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_NoncatastrophicEventAxis=mtg_IncreaseDecreaseInExpectedClaimRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_NoncatastrophicEventAxis=mtg_IncreaseDecreaseInEstimatedSeverityPrimaryDefaultsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_NoncatastrophicEventAxis=mtg_IncreaseDecreaseRelatedToIBNRPoolReservesLAEReservesandReinsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |