XML 46 R35.htm IDEA: XBRL DOCUMENT
v3.20.2

Non-controlling Interests (Tables) | 9 Months Ended
--- | ---
Sep. 30, 2020
Noncontrolling Interest [Abstract] |
Non-controlling Interests | The following table presents the balance of non-controlling interests included in White Mountains’s total equity and the related percentage of each consolidated entity’s total equity owned by non-controlling shareholders as of September 30, 2020 and December 31, 2019:
|  | September 30, 2020 |  | December 31, 2019
$ in Millions |  | Non-controlling Percentage |  | Non-controlling Equity |  | Non-controlling Percentage |  | Non-controlling Equity
Non-controlling interests, excluding BAM |  |  |  |  |  |  |  |
HG Global |  | 3.1 | % |  | $ | 14.1 |  |  | 3.1 | % |  | $ | 14.4 |
NSM |  | 3.4 | % |  | 16.9 |  |  | 3.6 | % |  | 14.9 |
Kudu |  | .8 | % |  | 2.2 |  |  | .9 | % |  | 2.2 |
Other |  | various |  |  | (1.3 | ) |  | various |  |  | (1.6 | )
Total, excluding BAM |  |  |  | 31.9 |  |  |  |  | 29.9 |
BAM |  | 100.0 | % |  | (130.4 | ) |  | 100.0 | % |  | (146.7 | )
Total non-controlling interests |  |  |  |  | $ | (98.5 | ) |  |  |  | $ | (116.8 | )

X
- References No definition available. + Details
Name: | us-gaap_NoncontrollingInterestAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Non-controlling Interests [Table Text Block] + References No definition available. + Details
Name: | wtm_NoncontrollingInterestsTableTextBlock
Namespace Prefix: | wtm_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration