XML 116 R108.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Derivatives (Variable Annuity Reinsurance Liabilities and Derivative Instruments) (Details) (White Mountains Life Re, USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Changes in derivative instruments |  |  |  |  |  |
Beginning of period | $ 98.3 |  |  |  |  |
Realized and unrealized gains (losses) | 402.0 |  | 339.0 |  | (92.9) |
Ending balance | 69.2 |  | 98.3 |  |  |
Level 3 |  |  |  |  |  |
Changes in variable annuity (liabilities) |  |  |  |  |  |
Beginning balance | (441.5) |  | (768.5) |  | (610.2) |
Purchases | 0 |  | 0 |  | 0 |
Realized and unrealized gains (losses) | (388.7) | [1] | (327.0) | [1] | 158.3 | [1]
Transfers in (out) | 0 |  | 0 |  | 0 |
Sales/settlements |  |  | 0 |  | 0 |
Ending balance | (52.8) |  | (441.5) |  | (768.5) |
Changes in derivative instruments |  |  |  |  |  |
Beginning of period | 140.5 | [2] | 247.1 | [2] | 275.3 | [2]
Purchases | 59.4 | [2] | 6.1 | [2] | 5.0 | [2]
Realized and unrealized gains (losses) | (136.5) | [2] | (84.0) | [2] | 14.5 | [2]
Transfers in (out) | 0 | [2] | 0 | [2] | 0 | [2]
Sales/settlements |  | [2] | (28.7) | [2] | (47.7) | [2]
Ending balance | 63.4 | [2] | 140.5 | [2] | 247.1 | [2]
Level 2 |  |  |  |  |  |
Changes in derivative instruments |  |  |  |  |  |
Beginning of period | (20.5) | [2],[3] | 39.2 | [2],[3] | 72.2 | [2],[3]
Purchases | 0 | [2],[3] | 0 | [2],[3] | 0 | [2],[3]
Realized and unrealized gains (losses) | (196.1) | [2],[3] | (186.9) | [2],[3] | 67.7 | [2],[3]
Transfers in (out) | 0 | [2],[3] | 0 | [2],[3] | 0 | [2],[3]
Sales/settlements | 221.3 | [2],[3] | 127.2 | [2],[3] | (100.7) | [2],[3]
Ending balance | 4.7 | [2],[3] | (20.5) | [2],[3] | 39.2 | [2],[3]
Level 1 |  |  |  |  |  |
Changes in derivative instruments |  |  |  |  |  |
Beginning of period | (21.7) | [4] | 4.1 | [4] | 0 | [4]
Purchases | 0 | [4] | 0 | [4] | 0 | [4]
Realized and unrealized gains (losses) | (69.4) | [4] | (68.1) | [4] | 10.7 | [4]
Transfers in (out) | 0 | [4] | 0 | [4] | 0 | [4]
Sales/settlements | 92.2 | [4] | 42.3 | [4] | (6.6) | [4]
Ending balance | 1.1 | [4] | (21.7) | [4] | 4.1 | [4]
Fair value |  |  |  |  |  |
Changes in derivative instruments |  |  |  |  |  |
Beginning of period | 98.3 | [5] | 290.4 | [5] | 347.5 | [5]
Purchases | 59.4 | [5] | 6.1 | [5] | 5.0 | [5]
Realized and unrealized gains (losses) | (402.0) | [5] | (339.0) | [5] | 92.9 | [5]
Transfers in (out) | 0 | [5] | 0 | [5] | 0 | [5]
Sales/settlements | 313.5 | [5] | 140.8 | [5] | (155.0) | [5]
Ending balance | $ 69.2 | [5] | $ 98.3 | [5] | $ 290.4 | [5]
[1] | Includes $10.2, $14.2, $(1.8) for December 31, 2013, 2012 and 2011 related to the change in the fair value of variable annuity death benefit liabilities, which are included in general and administrative expenses.
[2] | Consists of over-the-counter instruments.
[3] | Consists of interest rate swaps, total return swaps, foreign currency forward contracts, and bond forwards. Fair value measurement based upon bid/ask pricing quotes for similar instruments that are actively traded, where available. Swaps for which an active market does not exist have been priced using observable inputs including the swap curve and the underlying bond index.
[4] | Consists of exchange traded equity index, foreign currency and interest rate futures. Fair value measurements based upon quoted prices for identical instruments that are actively traded.
[5] | In addition to derivative instruments, WM Life Re held cash, short-term and fixed maturity investments of $81.3, $393.6 and $485.3 at December 31, 2013, 2012 and 2011 posted as collateral to its reinsurance counterparties.

X
- Definition Fair value of the assets less the liabilities of a derivative or group of derivatives. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5618551-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (a),(c),(d),(e) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959 + Details
Name: | us-gaap_DerivativeGainLossOnDerivativeNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of gain (loss) recognized on the income statement for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of purchases of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | wtm_DerivativeInstrumentsRollForward
Namespace Prefix: | wtm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Derivative Transfers In (Out), Net + References No definition available. + Details
Name: | wtm_DerivativeTransfersInOutNet
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Sales and settlements that have taken place during the period in relation to derivative assets measured at fair value on a recurring basis. + References No definition available. + Details
Name: | wtm_FairValueDerivativesMeasuredOnRecurringBasisAssetSalesAndSettlements
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers + References No definition available. + Details
Name: | wtm_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfers
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Sales or settlements that have taken place during the period in relation to liabilities measured at fair value and categorized within Level 3 of the fair value hierarchy. + References No definition available. + Details
Name: | wtm_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySalesOrSettlements
Namespace Prefix: | wtm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration