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Reinsurance (List of Direct, Assumed, and Ceded Reinsurance Amounts) (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017
Premiums written: |  |  |  |
Direct | $ 752,834 | $ 706,918 | $ 2,220,431 | $ 2,097,146
Assumed | 7,084 | 8,506 | 19,891 | 20,685
Ceded | (108,250) | (111,147) | (308,846) | (301,036)
Net | 651,668 | 604,277 | 1,931,476 | 1,816,795
Premiums earned: |  |  |  |
Direct | 706,497 | 666,048 | 2,086,953 | 1,967,364
Assumed | 6,484 | 7,623 | 19,220 | 19,465
Ceded | (98,704) | (101,616) | (295,232) | (285,890)
Net | 614,277 | 572,055 | 1,810,941 | 1,700,939
Loss and loss expenses incurred: |  |  |  |
Direct | 477,427 | 455,728 | 1,289,357 | 1,187,400
Assumed | 6,529 | 5,420 | 16,897 | 17,623
Ceded | (104,757) | (116,561) | (175,786) | (201,405)
Net | 379,199 | 344,587 | 1,130,468 | 1,003,618
National Flood Insurance Program [Member] |  |  |  |
Premiums written: |  |  |  |
Ceded | (70,100) | (68,132) | (193,110) | (188,274)
Premiums earned: |  |  |  |
Ceded | (61,448) | (59,847) | (180,582) | (174,779)
Loss and loss expenses incurred: |  |  |  |
Ceded | $ (89,396) | $ (112,994) | $ (115,376) | $ (134,675)

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