XML 82 R63.htm IDEA: XBRL DOCUMENT
v3.20.4

Reinsurance - Quota Share Reinsurance (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Effects of Reinsurance [Line Items] |  |  |
Ceded losses incurred | $ 77,975 | $ 11,400 | $ 6,829
Quota Share Reinsurance Agreements |  |  |
Effects of Reinsurance [Line Items] |  |  |
Ceded premiums written and earned, net of profit commission | 167,930 | 111,550 | 108,337
Ceded losses incurred | 78,012 | 11,395 | 6,543
Ceding commisisons | 48,077 | 48,793 | 51,201
Profit commission | $ 72,452 | $ 139,179 | $ 147,667

X
- Definition Ceded Premiums Written and Earned, Net of Profit Commission + References No definition available. + Details
Name: | mtg_CededPremiumsWrittenandEarnedNetofProfitCommission
Namespace Prefix: | mtg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Reinsurance Ceding Commission Earned + References No definition available. + Details
Name: | mtg_ReinsuranceCedingCommissionEarned
Namespace Prefix: | mtg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Reinsurance, Profit Commission + References No definition available. + Details
Name: | mtg_ReinsuranceProfitCommission
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 of reduction of provision for policy benefits and costs incurred for policies ceded. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=99397103&loc=d3e6811-158387 + Details
Name: | us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_ReinsurancePolicyTypeAxis=mtg_QuotaShareReinsuranceAgreementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |