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Reinsurance (List of Direct, Assumed, and Ceded Reinsurance Amounts) (Details) (USD $) | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013
Effects of Reinsurance [Line Items] |  |  |  |
Decrease in direct loss and loss expense incurred | $ 46,100,000 |  |  |
Premiums written: |  |  |  |
Direct | 592,858,000 | 570,849,000 | 1,723,063,000 | 1,650,855,000
Assumed | 5,780,000 | 22,053,000 | 19,467,000 | 34,913,000
Ceded premiums written | (103,517,000) | (100,154,000) | (290,836,000) | (280,719,000)
Net | 495,121,000 | 492,748,000 | 1,451,694,000 | 1,405,049,000
Premiums earned: |  |  |  |
Direct | 548,734,000 | 518,307,000 | 1,630,347,000 | 1,516,454,000
Assumed | 6,789,000 | 11,066,000 | 27,359,000 | 32,480,000
Ceded premiums earned | (92,884,000) | (91,805,000) | (274,947,000) | (264,174,000)
Net | 462,639,000 | 437,568,000 | 1,382,759,000 | 1,284,760,000
Loss and loss expense incurred: |  |  |  |
Direct | 304,525,000 | 350,648,000 | 995,581,000 | 1,055,248,000
Assumed | 5,362,000 | 7,264,000 | 20,218,000 | 22,758,000
Ceded loss and loss expense incurred | (38,955,000) | (74,595,000) | (126,526,000) | (245,246,000)
Net | 270,932,000 | 283,317,000 | 889,273,000 | 832,760,000
Percentage of NFIP claims ceded by federal government |  |  | 100.00% |
Hurricane Sandy [Member] |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |
Reduction in estimated ultimate exposure | 4,000,000 |  |  |
Hurricane Sandy [Member] | Catastrophe excess of loss treaty [Member] |  |  |  |
Effects of Reinsurance [Line Items] |  |  |  |
Reduction in estimated ultimate exposure | $ 3,600,000 |  |  |

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