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SCHEDULE IV REINSURANCE | 12 Months Ended
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Dec. 31, 2015
Supplemental Schedule of Reinsurance Premiums for Insurance Companies [Abstract] |
SCHEDULE IV REINSURANCE | WHITE MOUNTAINS INSURANCE GROUP, LTD. REINSURANCE(3) (Millions)
Column A |  | Column B |  | Column C |  | Column D |  | Column E |  | Column F
Premiums earned $ in millions |  | Gross amount |  | Ceded to other companies |  | Assumed from other companies |  | Net amount |  | Percentage of amount assumed to net
Years ended: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
December 31, 2015 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
OneBeacon (1) |  | $ | 1,298.0 |  |  | $ | (167.7 | ) |  | $ | 45.9 |  |  | $ | 1,176.2 |  |  | 3.9 | %
HG/BAM |  | 3.3 |  |  | — |  |  | — |  |  | 3.3 |  |  | — | %
Other operations(2) |  | 20.7 |  |  | (12.0 | ) |  | — |  |  | 8.7 |  |  | — |
December 31, 2014 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
OneBeacon(1) |  | $ | 1,209.1 |  |  | $ | (102.9 | ) |  | $ | 70.9 |  |  | $ | 1,177.1 |  |  | 6.0 | %
HG/BAM |  | 1.8 |  |  | — |  |  | — |  |  | 1.8 |  |  | — | %
Other operations(2) |  | 22.6 |  |  | (16.5 | ) |  | — |  |  | 6.1 |  |  | — |
December 31, 2013 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
OneBeacon(1) |  | $ | 1,043.3 |  |  | $ | (71.4 | ) |  | $ | 148.5 |  |  | $ | 1,120.4 |  |  | 13.3 | %
(1) | The amounts shown excludes balances reclassified to discontinued operations in the consolidated income statement related to the Runoff Transaction as of December 31, 2015, 2014 and 2013. See Note 22 - “Discontinued Operations”.
(2) | The Other operations amounts shown relate to SSIE. SSIE’s results are attributed to non-controlling interests.
(3) Schedule excludes activity related to Sirius Group for all periods presented. See Note 22 - “Discontinued Operations”. Schedules of the Registrant should be read in conjunction with the Consolidated Financial Statements and Notes.

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- Definition The entire disclosure for the supplemental schedule of reinsurance information. Reinsurance schedule includes, but is not limited to, the type of insurance, gross amount of premiums, premiums ceded to other entities, premiums assumed from other entities, net amount of premium revenue, and the percentage of the premiums assumed to net premium revenue. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 235 -Section S99 -Paragraph 2 -Subparagraph (SX 210.12-17) -URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.7-05.(c) Schedule IV) -URI http://asc.fasb.org/extlink&oid=6879921&loc=d3e569147-122900 + Details
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