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Debt (Details) - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Nov. 30, 2012 | Mar. 31, 2017 | Mar. 31, 2016 | Dec. 31, 2012 | Dec. 31, 2016 | Jul. 23, 2015 | Aug. 14, 2013
Debt Instrument |  |  |  |  |  |  |
Total debt |  | $ 284.7 |  |  | $ 285.9 |  |
Notional amount |  | 299.9 |  |  |  |  |
Repayments of Debt |  | 1.2 | $ 0.0 |  |  |  |
Draw down of debt and revolving line of credit |  | $ 0.0 | $ 102.5 |  |  |  |
MediaAlpha Bank Facility [Member] |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Basis points |  | 1.50% |  |  |  |  |
2012 OBH Senior Notes |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Proceeds from Issuance of Debt |  |  |  | $ 275.0 |  |  |
WTM Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total commitment under revolving credit facility |  |  |  |  |  |  | $ 425.0
OB Bank Facility [Member] |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total commitment under revolving credit facility |  | $ 65.0 |  |  |  |  |
One Beacon Holdings Inc [Member] | 2012 OBH Senior Notes |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Effective Percentage | 4.70% |  |  |  |  |  |
Proceeds from Issuance of Debt | $ 272.9 |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 4.60% |  |  |  |  |  |
Debt Instrument, Issue Price as Percentage of Par Value | 99.90% |  |  |  |  |  |
OneBeacon [Member] | 2012 OBH Senior Notes |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Debt instrument at face value |  | 275.0 |  |  | 275.0 |  |
Unamortized original issue discount |  | (1.8) |  |  | (1.8) |  |
Total debt |  | $ 273.2 |  |  | $ 273.2 |  |
Debt Instrument, Interest Rate, Effective Percentage |  | 4.70% |  |  | 4.70% |  |
White Mountains | WTM Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt |  | $ 0.0 |  |  | $ 0.0 |  |
MediaAlpha [Member] | MediaAlpha Bank Facility [Member] |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Debt instrument at face value |  | $ 11.7 |  |  | $ 12.9 |  |
Debt Instrument, Interest Rate, Effective Percentage |  | 6.10% |  |  | 5.70% |  |
Unamortized Debt Issuance Expense |  | $ (0.2) |  |  | $ (0.2) |  |
Line of Credit Facility, Fair Value of Amount Outstanding |  | 11.5 |  |  | $ 12.7 |  |
Total commitment under revolving credit facility |  |  |  |  |  | $ 20.0 |
Notional amount |  | 15.0 |  |  |  |  |
Line of Credit Facility, Remaining Borrowing Capacity |  | 5.0 |  |  |  |  |
MediaAlpha [Member] | Term Loan [Member] |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Repayments of Debt |  | 1.2 |  |  |  |  |
Debt Instrument, Redemption, Period One [Member] | OneBeacon [Member] | 2012 OBH Senior Notes |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt |  | $ 75.0 |  |  |  |  |

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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 Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3255-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(f)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
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