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Reinsurance (List of Direct, Assumed, and Ceded Reinsurance Amounts) (Details) (USD $) In Thousands, unless otherwise specified | 3 Months Ended
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Mar. 31, 2014 | Mar. 31, 2013
Premiums written: |  |
Direct | $ 557,891 | $ 528,816
Assumed | 7,850 | 8,482
Ceded premiums written | (88,991) | (87,174)
Net | 476,750 | 450,124
Premiums earned: |  |
Direct | 536,700 | 494,066
Assumed | 10,185 | 12,463
Ceded premiums earned | (90,390) | (85,589)
Net | 456,495 | 420,940
Loss and loss expense incurred: |  |
Direct | 358,349 | 365,646
Assumed | 7,479 | 9,074
Ceded loss and loss expense incurred | (45,282) | (104,871)
Net | $ 320,546 | $ 269,849
Number of insurance subsidiaries | 10 |
Percentage of NFIP claims ceded by federal government | 100.00% |

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