XML 71 R60.htm IDEA: XBRL DOCUMENT
v3.20.2

Goodwill and Other Intangible Assets - Fair Value of Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended | 12 Months Ended |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019 | Dec. 31, 2019 | Apr. 07, 2020 | Mar. 31, 2020 | Jun. 28, 2019 | Apr. 04, 2019 | Apr. 01, 2019 | Mar. 31, 2019 | Mar. 12, 2019 | Dec. 31, 2018
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill, acquisition date fair value | $ 518.2 |  | $ 518.2 |  | $ 402.3 |  |  |  |  |  |  |  |
Goodwill, Impairment Loss |  |  |  |  | 7.6 |  |  |  |  |  |  |  |
Goodwill and other intangible assets | 759.9 |  | 759.9 |  | 654.7 |  |  |  |  |  |  |  |
Goodwill | 518.2 |  | 518.2 |  | 394.7 |  |  |  |  |  |  |  |
Impairment of Intangible Assets, Finite-lived |  |  |  |  | 10.4 |  |  |  |  |  |  |  |
Renewal Rights |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill and intangible assets acquired |  |  |  |  |  |  |  | $ 82.5 |  |  |  |  |
Kingsbridge [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill and intangible assets acquired |  |  |  |  |  | $ 125.1 |  |  |  |  |  |  |
NSM Holding Co LLC |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill, acquisition date fair value | 504.9 |  | 504.9 |  | 381.6 |  |  |  |  |  |  |  |
Goodwill and intangible assets acquired | 275.2 |  | 275.2 |  |  |  |  |  |  |  |  |  |
Goodwill | 504.9 |  | 504.9 |  | 381.6 |  |  |  |  |  |  |  |
Impairment of Intangible Assets, Finite-lived |  |  |  |  | 2.4 |  |  |  |  |  |  |  |
NSM Holding Co LLC | Renewal Rights |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Impairment of Intangible Assets, Finite-lived |  |  |  |  | 0.0 |  |  |  |  |  |  |  |
Kudu investments |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill, acquisition date fair value | 7.6 |  | 7.6 |  | 7.6 |  |  |  |  |  |  |  |
Goodwill | 7.6 |  | 7.6 |  | 7.6 |  |  |  |  |  |  |  |
Other [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill, acquisition date fair value | 5.7 |  | 5.7 |  | 13.1 |  |  |  |  |  |  |  |
Goodwill, Impairment Loss |  |  |  |  | 7.6 |  |  |  |  |  |  |  |
Goodwill | 5.7 |  | 5.7 |  | 5.5 |  |  |  |  |  |  |  |
Impairment of Intangible Assets, Finite-lived |  |  |  |  | 0.4 |  |  |  |  |  |  |  |
Embrace Pet Insurance |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Capitalized Computer Software, Additions |  | $ 3.4 |  |  |  |  |  |  |  |  |  |  |
Goodwill and intangible assets acquired |  |  |  |  |  |  |  |  |  | $ 67.6 |  |  |
Goodwill |  |  |  |  |  |  |  |  |  | $ 52.2 |  |  |
Kudu |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill and intangible assets acquired |  |  |  |  |  |  |  |  | $ 9.8 |  |  |  |
Other Operations |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill and intangible assets acquired |  |  |  |  |  |  |  |  |  |  |  | $ 22.6 |
Goodwill |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill, Foreign Currency Translation Gain (Loss) | 0.7 | (1.2) | (1.8) | $ 0.0 |  |  |  |  |  |  |  |  |
Goodwill | 518.2 | $ 428.6 | 518.2 | $ 428.6 | 394.7 |  | $ 392.4 |  |  |  | $ 349.7 |  | $ 379.9
Other Intangible Assets | NSM Holding Co LLC |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss) |  |  | (0.4) |  | 0.7 |  |  |  |  |  |  |  |
Fresh Insurance Services Group Limited |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Impairment of Intangible Assets, Finite-lived |  |  | 6.2 |  |  |  |  |  |  |  |  |  |
Fresh Insurance Services Group Limited | NSM Holding Co LLC |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Impairment of Intangible Assets, Finite-lived |  |  | 6.2 |  |  |  |  |  |  |  |  |  |
Fresh Insurance Services Group Limited | NSM Holding Co LLC | Renewal Rights |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Impairment of Intangible Assets, Finite-lived |  |  | 0.0 |  |  |  |  |  |  |  |  |  |
NSM Holding Co LLC |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill and other intangible assets | $ 728.6 |  | 728.6 |  | 623.0 |  |  |  |  |  |  |  |
NSM Holding Co LLC | Goodwill |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill, Foreign Currency Translation Gain (Loss) |  |  | $ (1.8) |  | $ 1.4 |  |  |  |  |  |  |  |

X
- Definition Additions made to capitalized computer software costs during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275 + Details
Name: | us-gaap_CapitalizedComputerSoftwareAdditions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of foreign currency translation gain (loss) which increases (decreases) assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References No definition available. + Details
Name: | us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266 + Details
Name: | us-gaap_Goodwill
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
Name: | us-gaap_GoodwillFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267 + Details
Name: | us-gaap_GoodwillForeignCurrencyTranslationGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13854-109267 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13777-109266 + Details
Name: | us-gaap_GoodwillImpairmentLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_GoodwillLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of a finite-lived intangible asset to fair value. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16373-109275 + Details
Name: | us-gaap_ImpairmentOfIntangibleAssetsFinitelived
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Carrying amount of finite-lived intangible assets, indefinite-lived intangible assets and goodwill. Goodwill is an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Intangible assets are assets, not including financial assets, lacking physical substance. + References No definition available. + Details
Name: | us-gaap_IntangibleAssetsNetIncludingGoodwill
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Goodwill and Intangible Assets + References No definition available. + Details
Name: | wtm_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedGoodwillandIntangibleAssets
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=wtm_RenewalRightsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=wtm_KingsbridgeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=wtm_NSMInsuranceGroupMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=wtm_KuduInvestmentManagementLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=wtm_OtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=wtm_EmbracePetInsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=wtm_KuduMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=wtm_OtherOperationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_GoodwillMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_OtherIntangibleAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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