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Debt (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Sep. 30, 2017 | Sep. 30, 2017 | Sep. 30, 2016 | May 12, 2017 | Dec. 31, 2016 | Jul. 23, 2015 | Aug. 14, 2013
Debt Instrument |  |  |  |  |  |  |
Total debt | $ 9.4 | $ 9.4 |  |  | $ 12.7 |  |
Repayments of debt |  | 364.6 | $ 401.8 |  |  |  |
Draw down of debt and revolving line of credit |  | 361.0 | $ 352.5 |  |  |  |
WTM Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total commitment under revolving credit facility |  |  |  |  |  |  | $ 425.0
White Mountains | WTM Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt | 0.0 | 0.0 |  |  | 0.0 |  |
MediaAlpha | MediaAlpha Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Debt Instrument, Face Amount | 9.4 | 9.4 |  |  |  |  |
Unamortized issuance cost | $ 0.0 | $ 0.0 |  |  |  |  |
Debt instrument, interest rate, effective percentage | 5.50% | 5.50% |  |  |  |  |
Total commitment under revolving credit facility |  |  |  | $ 20.0 |  |  |
Long-term line of credit | $ 9.4 | $ 9.4 |  |  |  |  |
Draw down of debt and revolving line of credit |  | 6.0 |  |  |  |  |
MediaAlpha | Previous MediaAlpha Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Debt Instrument, Face Amount | 0.0 | 0.0 |  |  | 12.9 |  |
Unamortized issuance cost | 0.0 | 0.0 |  |  | $ (0.2) |  |
Debt instrument, interest rate, effective percentage |  |  |  |  | 5.70% |  |
Total commitment under revolving credit facility |  |  |  |  |  | $ 20.0 |
Repayments of debt |  | 12.9 |  |  |  |  |
Long-term line of credit | 0.0 | 0.0 |  |  | $ 12.7 |  |
OneBeacon | 2012 OBH Senior Notes |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt | 0.0 | 0.0 |  |  | 0.0 |  |
Unamortized issuance cost | 0.0 | $ 0.0 |  |  | $ 0.0 |  |
Term Loan | MediaAlpha Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Basis points |  | 1.50% |  |  |  |  |
Term Loan | MediaAlpha | MediaAlpha Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total commitment under revolving credit facility | 5.0 | $ 5.0 |  |  |  |  |
Repayments of debt |  | 1.6 |  |  |  |  |
Long-term line of credit | 3.4 | 3.4 |  |  |  |  |
Proceeds from issuance of debt |  | 5.0 |  |  |  |  |
Revolving Credit Facility [Member] | MediaAlpha | MediaAlpha Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total commitment under revolving credit facility | 15.0 | 15.0 |  |  |  |  |
Long-term line of credit | 6.0 | $ 6.0 |  |  |  |  |
Line of Credit | MediaAlpha Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Basis points |  | 0.25% |  |  |  |  |
Line of Credit | White Mountains | WTM Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Repayments of debt | $ 350.0 | $ 350.0 |  |  |  |  |

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- Definition Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399 + Details
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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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