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Reinsurance (List of Direct, Assumed, and Ceded Reinsurance Amounts) (Details) (USD $) | 3 Months Ended | 9 Months Ended |  | 9 Months Ended
--- | --- | --- | --- | ---
Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2013 Hurricane Sandy [Member] | Dec. 31, 2012 Hurricane Sandy [Member] | Sep. 30, 2013 National Flood Insurance Program [Member] Hurricane Sandy [Member]
Premiums written: |  |  |  |  |  |  |
Direct | $ 570,849,000 | $ 520,943,000 | $ 1,650,855,000 | $ 1,504,429,000 |  |  |
Assumed | 22,053,000 | 17,976,000 | 34,913,000 | 44,712,000 |  |  |
Ceded premiums written | (100,154,000) | (88,401,000) | (280,719,000) | (252,888,000) |  |  |
Net | 492,748,000 | 450,518,000 | 1,405,049,000 | 1,296,253,000 |  |  |
Premiums earned: |  |  |  |  |  |  |
Direct | 518,307,000 | 474,055,000 | 1,516,454,000 | 1,389,373,000 |  |  |
Assumed | 11,066,000 | 18,595,000 | 32,480,000 | 49,683,000 |  |  |
Ceded premiums earned | (91,805,000) | (86,425,000) | (264,174,000) | (261,790,000) |  |  |
Net | 437,568,000 | 406,225,000 | 1,284,760,000 | 1,177,266,000 |  |  |
Loss and loss expense incurred: |  |  |  |  |  |  |
Direct | 350,648,000 | 327,883,000 | 1,055,248,000 | 881,537,000 | 128,000,000 |  |
Assumed | 7,264,000 | 13,970,000 | 22,758,000 | 35,039,000 |  |  |
Ceded loss and loss expense incurred | (74,595,000) | (69,602,000) | (245,246,000) | (103,516,000) |  |  |
Net | 283,317,000 | 272,251,000 | 832,760,000 | 813,060,000 |  |  |
Number of insurance subsidiaries |  |  | 10 |  |  |  |
Estimated flood gross losses |  |  |  |  | 1,179,000,000 | 1,052,000,000 |
Percentage of unpaid NFIP claims ceded by federal government |  |  | 100.00% |  |  |  |
Flood Losses Paid |  |  |  |  |  |  | $ 1,148,000,000

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