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Derivatives (Pre-Tax Operating Results of WM Life Re) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2012 | Sep. 30, 2012 | Jun. 30, 2012 | Mar. 31, 2012 | Dec. 31, 2011 | Sep. 30, 2011 | Jun. 30, 2011 | Mar. 31, 2011 | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010
Pre-tax operating results of WM Life Re |  |  |  |  |  |  |  |  |  |  |
Change in fair value of variable annuity liability, included in other revenues |  |  |  |  |  |  |  |  |  | $ 7.2 | $ 47.7
Total revenues | 566.4 | 697.4 | 542.3 | 629.7 | 593.4 | 501.7 | 552.4 | 525.6 | 2,435.7 | 2,173.1 | 2,333.7
General and administrative expenses |  |  |  |  |  |  |  |  | (182.2) | (175.3) | (155.0)
Pre-tax income | (50.8) | 135.1 | 37.6 | 140.9 | 98.4 | 1.2 | 35.8 | (37.4) | 262.8 | 98.0 | 189.3
White Mountains Life Re |  |  |  |  |  |  |  |  |  |  |
Pre-tax operating results of WM Life Re |  |  |  |  |  |  |  |  |  |  |
Fees, included in other revenues |  |  |  |  |  |  |  |  | 31.8 | 32.5 | 30.2
Change in fair value of variable annuity liability, included in other revenues |  |  |  |  |  |  |  |  | 312.8 | (156.5) | (223.5)
Change in fair value of derivatives, included in other revenues |  |  |  |  |  |  |  |  | (339.0) | 92.9 | 127.0
Foreign exchange, included in other revenues |  |  |  |  |  |  |  |  | (30.3) | 15.1 | 21.4
Other investment income and gains (losses) |  |  |  |  |  |  |  |  | 2.5 | (0.9) | (0.9)
Total revenues |  |  |  |  |  |  |  |  | (22.2) | (16.9) | (45.8)
Change in fair value of variable annuity death benefit liabilities, included in general and administrative expenses |  |  |  |  |  |  |  |  | 14.2 | (1.8) | (6.0)
Death benefit claims paid, included in general and administrative expenses |  |  |  |  |  |  |  |  | (5.7) | (3.8) | (2.7)
General and administrative expenses |  |  |  |  |  |  |  |  | (5.2) | (4.7) | (6.3)
Pre-tax income |  |  |  |  |  |  |  |  | $ (18.9) | $ (27.2) | $ (60.8)

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- Definition Monetary decrease in the future benefit reserve resulting from amounts paid to policy and contract holders during the period for policy benefit claims. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Financial Reporting Release (FRR) -Number 403 -Paragraph 04 -Subparagraph b Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6482485&loc=d3e14764-158437 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-LHI -Paragraph 2, 27 -IssueDate 2006-05-01 -Chapter 9 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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