    <SEC-DOCUMENT>0000776867-20-000011-index.html : 20200330
    <SEC-HEADER>0000776867-20-000011.hdr.sgml : 20200330
    <ACCEPTANCE-DATETIME>20200330092037
    ACCESSION NUMBER:		0000776867-20-000011
    CONFORMED SUBMISSION TYPE:	10-K/A
    PUBLIC DOCUMENT COUNT:		63
    CONFORMED PERIOD OF REPORT:	20191231
    FILED AS OF DATE:		20200330
    DATE AS OF CHANGE:		20200330

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			WHITE MOUNTAINS INSURANCE GROUP LTD
    		CENTRAL INDEX KEY:			0000776867
    		STANDARD INDUSTRIAL CLASSIFICATION:	FIRE, MARINE & CASUALTY INSURANCE [6331]
    		IRS NUMBER:				942708455
    		STATE OF INCORPORATION:			D0
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		10-K/A
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	001-08993
    		FILM NUMBER:		20754400

    	BUSINESS ADDRESS:
    		STREET 1:		80 SOUTH MAIN ST
    		CITY:			HANOVER
    		STATE:			NH
    		ZIP:			03755
    		BUSINESS PHONE:		603 640 2200

    	MAIL ADDRESS:
    		STREET 1:		80 SOUTH MAIN STREET
    		CITY:			HANOVER
    		STATE:			NH
    		ZIP:			03755

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	WHITE MOUNTAINS INSURANCE GROUP INC
    		DATE OF NAME CHANGE:	19990603

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	FUND AMERICAN ENTERPRISES HOLDINGS INC
    		DATE OF NAME CHANGE:	19920703

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	FUND AMERICAN COMPANIES INC
    		DATE OF NAME CHANGE:	19920701
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>10-K/A
    <SEQUENCE>1
    <FILENAME>wtm10-ka2019ma.htm
    <DESCRIPTION>10-K/A
    <TEXT>
    Document 1 - file: wtm10-ka2019ma.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-23.1
    <SEQUENCE>2
    <FILENAME>wtm10-ka2019ex231.htm
    <DESCRIPTION>EXHIBIT 23.1
    <TEXT>
    Document 2 - file: wtm10-ka2019ex231.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-31.1
    <SEQUENCE>3
    <FILENAME>wtm10-ka2019ex311.htm
    <DESCRIPTION>EXHIBIT 31.1
    <TEXT>
    Document 3 - file: wtm10-ka2019ex311.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-31.2
    <SEQUENCE>4
    <FILENAME>wtm10-ka2019ex312.htm
    <DESCRIPTION>EXHIBIT 31.2
    <TEXT>
    Document 4 - file: wtm10-ka2019ex312.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-32.1
    <SEQUENCE>5
    <FILENAME>wtm10-ka2019ex321.htm
    <DESCRIPTION>EXHIBIT 32.1
    <TEXT>
    Document 5 - file: wtm10-ka2019ex321.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-32.2
    <SEQUENCE>6
    <FILENAME>wtm10-ka2019ex322.htm
    <DESCRIPTION>EXHIBIT 32.2
    <TEXT>
    Document 6 - file: wtm10-ka2019ex322.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.1
    <SEQUENCE>7
    <FILENAME>wtm10ka2019ex991.htm
    <DESCRIPTION>EXHIBIT 99.1
    <TEXT>
    Document 7 - file: wtm10ka2019ex991.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.2
    <SEQUENCE>8
    <FILENAME>wtm10ka2019ex992.htm
    <DESCRIPTION>EXHIBIT 99.2
    <TEXT>
    Document 8 - file: wtm10ka2019ex992.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.SCH
    <SEQUENCE>9
    <FILENAME>wtm-20191231.xsd
    <DESCRIPTION>XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT
    <TEXT>
    Document 9 - file: wtm-20191231.xsd

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.CAL
    <SEQUENCE>10
    <FILENAME>wtm-20191231_cal.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION CALCULATION LINKBASE DOCUMENT
    <TEXT>
    Document 10 - file: wtm-20191231_cal.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.DEF
    <SEQUENCE>11
    <FILENAME>wtm-20191231_def.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION DEFINITION LINKBASE DOCUMENT
    <TEXT>
    Document 11 - file: wtm-20191231_def.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.LAB
    <SEQUENCE>12
    <FILENAME>wtm-20191231_lab.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION LABEL LINKBASE DOCUMENT
    <TEXT>
    Document 12 - file: wtm-20191231_lab.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.PRE
    <SEQUENCE>13
    <FILENAME>wtm-20191231_pre.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE DOCUMENT
    <TEXT>
    Document 13 - file: wtm-20191231_pre.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>14
    <FILENAME>wtm10ka2019ex991001.jpg
    <TEXT>
    Document 14 - file: wtm10ka2019ex991001.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>15
    <FILENAME>wtm10ka2019ex991002.jpg
    <TEXT>
    Document 15 - file: wtm10ka2019ex991002.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>16
    <FILENAME>wtm10ka2019ex991003.jpg
    <TEXT>
    Document 16 - file: wtm10ka2019ex991003.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>17
    <FILENAME>wtm10ka2019ex991004.jpg
    <TEXT>
    Document 17 - file: wtm10ka2019ex991004.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>18
    <FILENAME>wtm10ka2019ex991005.jpg
    <TEXT>
    Document 18 - file: wtm10ka2019ex991005.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>19
    <FILENAME>wtm10ka2019ex991006.jpg
    <TEXT>
    Document 19 - file: wtm10ka2019ex991006.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>20
    <FILENAME>wtm10ka2019ex991007.jpg
    <TEXT>
    Document 20 - file: wtm10ka2019ex991007.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>21
    <FILENAME>wtm10ka2019ex991008.jpg
    <TEXT>
    Document 21 - file: wtm10ka2019ex991008.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>22
    <FILENAME>wtm10ka2019ex991009.jpg
    <TEXT>
    Document 22 - file: wtm10ka2019ex991009.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>23
    <FILENAME>wtm10ka2019ex991010.jpg
    <TEXT>
    Document 23 - file: wtm10ka2019ex991010.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>24
    <FILENAME>wtm10ka2019ex991011.jpg
    <TEXT>
    Document 24 - file: wtm10ka2019ex991011.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>25
    <FILENAME>wtm10ka2019ex991012.jpg
    <TEXT>
    Document 25 - file: wtm10ka2019ex991012.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>26
    <FILENAME>wtm10ka2019ex991013.jpg
    <TEXT>
    Document 26 - file: wtm10ka2019ex991013.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>27
    <FILENAME>wtm10ka2019ex991014.jpg
    <TEXT>
    Document 27 - file: wtm10ka2019ex991014.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>28
    <FILENAME>wtm10ka2019ex991015.jpg
    <TEXT>
    Document 28 - file: wtm10ka2019ex991015.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>29
    <FILENAME>wtm10ka2019ex991016.jpg
    <TEXT>
    Document 29 - file: wtm10ka2019ex991016.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>30
    <FILENAME>wtm10ka2019ex991017.jpg
    <TEXT>
    Document 30 - file: wtm10ka2019ex991017.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>31
    <FILENAME>wtm10ka2019ex991018.jpg
    <TEXT>
    Document 31 - file: wtm10ka2019ex991018.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>32
    <FILENAME>wtm10ka2019ex991019.jpg
    <TEXT>
    Document 32 - file: wtm10ka2019ex991019.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>33
    <FILENAME>wtm10ka2019ex991020.jpg
    <TEXT>
    Document 33 - file: wtm10ka2019ex991020.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>34
    <FILENAME>wtm10ka2019ex991021.jpg
    <TEXT>
    Document 34 - file: wtm10ka2019ex991021.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>35
    <FILENAME>wtm10ka2019ex992001.jpg
    <TEXT>
    Document 35 - file: wtm10ka2019ex992001.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>36
    <FILENAME>wtm10ka2019ex992002.jpg
    <TEXT>
    Document 36 - file: wtm10ka2019ex992002.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>37
    <FILENAME>wtm10ka2019ex992003.jpg
    <TEXT>
    Document 37 - file: wtm10ka2019ex992003.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>38
    <FILENAME>wtm10ka2019ex992004.jpg
    <TEXT>
    Document 38 - file: wtm10ka2019ex992004.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>39
    <FILENAME>wtm10ka2019ex992005.jpg
    <TEXT>
    Document 39 - file: wtm10ka2019ex992005.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>40
    <FILENAME>wtm10ka2019ex992006.jpg
    <TEXT>
    Document 40 - file: wtm10ka2019ex992006.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>41
    <FILENAME>wtm10ka2019ex992007.jpg
    <TEXT>
    Document 41 - file: wtm10ka2019ex992007.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>42
    <FILENAME>wtm10ka2019ex992008.jpg
    <TEXT>
    Document 42 - file: wtm10ka2019ex992008.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>43
    <FILENAME>wtm10ka2019ex992009.jpg
    <TEXT>
    Document 43 - file: wtm10ka2019ex992009.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>44
    <FILENAME>wtm10ka2019ex992010.jpg
    <TEXT>
    Document 44 - file: wtm10ka2019ex992010.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>45
    <FILENAME>wtm10ka2019ex992011.jpg
    <TEXT>
    Document 45 - file: wtm10ka2019ex992011.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>46
    <FILENAME>wtm10ka2019ex992012.jpg
    <TEXT>
    Document 46 - file: wtm10ka2019ex992012.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>47
    <FILENAME>wtm10ka2019ex992013.jpg
    <TEXT>
    Document 47 - file: wtm10ka2019ex992013.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>48
    <FILENAME>wtm10ka2019ex992014.jpg
    <TEXT>
    Document 48 - file: wtm10ka2019ex992014.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>49
    <FILENAME>wtm10ka2019ex992015.jpg
    <TEXT>
    Document 49 - file: wtm10ka2019ex992015.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>50
    <FILENAME>wtm10ka2019ex992016.jpg
    <TEXT>
    Document 50 - file: wtm10ka2019ex992016.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>51
    <FILENAME>wtm10ka2019ex992017.jpg
    <TEXT>
    Document 51 - file: wtm10ka2019ex992017.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>52
    <FILENAME>wtm10ka2019ex992018.jpg
    <TEXT>
    Document 52 - file: wtm10ka2019ex992018.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>53
    <FILENAME>wtm10ka2019ex992019.jpg
    <TEXT>
    Document 53 - file: wtm10ka2019ex992019.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>54
    <FILENAME>wtm10ka2019ex992020.jpg
    <TEXT>
    Document 54 - file: wtm10ka2019ex992020.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>55
    <FILENAME>wtm10ka2019ex992021.jpg
    <TEXT>
    Document 55 - file: wtm10ka2019ex992021.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>JSON
    <SEQUENCE>56
    <FILENAME>MetaLinks.json
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 56 - file: MetaLinks.json

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>ZIP
    <SEQUENCE>57
    <FILENAME>0000776867-20-000011-xbrl.zip
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 57 - file: 0000776867-20-000011-xbrl.zip

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>58
    <FILENAME>FilingSummary.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 58 - file: FilingSummary.html

    Document 58 - RAW XML: FilingSummary.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>59
    <FILENAME>Show.js
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 59 - file: Show.js

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EXCEL
    <SEQUENCE>62
    <FILENAME>Financial_Report.xlsx
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 62 - file: Financial_Report.xlsx

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>63
    <FILENAME>wtm10-ka2019ma_htm.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 63 - file: wtm10-ka2019ma_htm.html

    Document 63 - RAW XML: wtm10-ka2019ma_htm.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>64
    <FILENAME>R1.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 64 - file: R1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>65
    <FILENAME>report.css
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 65 - file: report.css

    </DOCUMENT>
    </SEC-DOCUMENT>