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v3.3.1.900

Common Shareholders’ Equity and Non-controlling Interests (Details) - USD ($) $ / shares in Units, $ in Millions | 1 Months Ended | 12 Months Ended
--- | --- | ---
May. 31, 2007 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Common Shares Repurchased and Retired [Abstract] |  |  |  |  |
Value of common shares repurchased and retired during the period |  | $ 284.2 | $ 134.5 | $ 79.8 |
Value of each common share repurchased and retired during the period (in dollars per share) |  | $ 733 | $ 617 | $ 564 |
Common Shares Issued [Abstract] |  |  |  |  |
Stock Issued During Period, Shares, New Issues |  | 25,016 | 28,405 | 27,310 |
Shares issued to directors (in shares) |  | 1,376 | 1,395 | 1,590 |
Dividends, Common Stock [Abstract] |  |  |  |  |
Cash dividends declared and paid |  | $ 6.0 | $ 6.2 | $ 6.2 |
Dividends delared and paid (in dollars per share) |  | $ 1.00 | $ 1.00 | $ 1.00 |
Non-controlling interests |  | $ 454.8 | $ 542.7 |  |
Non-controlling Interests |  |  |  |  |
Common Shares Repurchased and Retired [Abstract] |  |  |  |  |
Value of common shares repurchased and retired during the period |  | 0.0 | 0.0 | $ 0.0 |
Total Non-Controlling Excluding Reciprocals [Member] |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Non-controlling interests |  | $ 115.2 | $ 168.6 |  |
Restricted Stock |  |  |  |  |
Common Shares Issued [Abstract] |  |  |  |  |
Stock Issued During Period, Shares, New Issues |  | 23,640 | 23,440 | 25,720 |
Performance Shares |  |  |  |  |
Common Shares Issued [Abstract] |  |  |  |  |
Stock Issued During Period, Shares, New Issues |  |  | 3,570 |  |
Common Stock |  |  |  |  |
Common Shares Repurchased and Retired [Abstract] |  |  |  |  |
Common shares repurchased and retired during the period |  | 387,495 | 217,879 | 141,535 |
General Board Authorization [Member] |  |  |  |  |
Common Shares Repurchased and Retired [Abstract] |  |  |  |  |
Additional authorized repurchase of common shares |  | 476,253 |  |  |
Common shares repurchased and retired during the period |  | 361,839 | 207,404 | 140,000 |
Value of common shares repurchased and retired during the period |  | $ 267.4 | $ 128.2 | $ 78.9 |
Value of each common share repurchased and retired during the period (in dollars per share) |  | $ 739 | $ 618 | $ 564 |
Repurchased for Employee Benefit Plans [Member] |  |  |  |  |
Common Shares Repurchased and Retired [Abstract] |  |  |  |  |
Common shares repurchased and retired during the period |  | 10,802 |  | 1,535 |
Repurchased for Employee Benefit Plans [Member] | Combination Three [Member] |  |  |  |  |
Common Shares Repurchased and Retired [Abstract] |  |  |  |  |
Common shares repurchased and retired during the period |  |  | 10,475 |  |
White Mountains |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Capital contributions |  |  |  |  | $ 594.5
Sirius Internation Group Ltd | Preferred stocks |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Preference shares floating rate of dividend amount in excess of libor | 3.20% |  |  |  |
Preferred Stock Redemption Basis Spread on Treasury Issue Rate | 45.00% |  |  |  |
OneBeacon Ltd. |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners |  | 24.50% | 24.70% |  |
Non-controlling interests |  | $ 245.6 | $ 258.4 |  |
HG/BAM [Member] |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners |  | 100.00% | 100.00% |  |
Non-controlling interests |  | $ (140.0) | $ (121.9) |  |
Star & Shield Insurance Exchange [Member] |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners |  | 100.00% | 100.00% |  |
Non-controlling interests |  | $ (16.0) | $ (12.4) |  |
HG Global |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners |  | 3.10% | 3.10% |  |
Non-controlling interests |  | $ 17.1 | $ 17.9 |  |
MediaAlpha |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners |  | 40.00% | 40.00% |  |
Non-controlling interests |  | $ 14.4 | $ 22.6 |  |
Tranzact [Member] |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners |  | 36.80% | 36.80% |  |
Non-controlling interests |  | $ 79.4 | $ 88.2 |  |
WOBI [Member] |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners |  | 3.90% | 36.70% |  |
Non-controlling interests |  | $ 0.6 | $ 5.4 |  |
Prospector Offshore Fund Ltd [Member] |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners |  | 0.00% | 23.40% |  |
Non-controlling interests |  | $ 0.0 | $ 31.1 |  |
A W G Dewar Inc [Member] |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners |  | 19.00% | 18.00% |  |
Non-controlling interests |  | $ 3.7 | $ 3.4 |  |
SIG Preference Shares |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners |  | 100.00% | 100.00% |  |
Non-controlling interests |  | $ 250.0 | $ 250.0 |  |
BAM Management |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Capital contributions |  |  |  |  | $ 14.5
OneBeacon |  |  |  |  |
Dividends, Common Stock [Abstract] |  |  |  |  |
Non-controlling interests |  | $ 249.3 | $ 261.8 |  |

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- Definition Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which is directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent (that is, noncontrolling interest, previously referred to as minority interest). + 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 210.5-02.31) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 27 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 20 -Article 7 + Details
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