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Third Party Reinsurance (Written and Earned Premiums) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Written premiums: |  |  |
Direct | $ 1,245.2 | $ 1,325.7 | $ 1,296.3
Assumed | 28.0 | 36.0 | 65.9
Gross written premiums | 1,273.2 | 1,361.7 | 1,362.2
Ceded | (127.4) | (189.1) | (123.2)
Net written premiums | 1,145.8 | 1,172.6 | 1,239.0
Earned premiums: |  |  |
Direct Premiums amount | 1,198.1 | 1,322.0 | 1,233.5
Assumed | 29.4 | 45.9 | 70.9
Gross earned premiums | 1,227.5 | 1,367.9 | 1,304.4
Ceded | (113.5) | (179.7) | (119.4)
Net earned premiums | 1,114.0 | 1,188.2 | 1,185.0
Losses and LAE: |  |  |
Direct | 693.8 | 802.5 | 802.8
Assumed | 21.2 | 55.7 | 115.7
Gross losses and LAE | 715.0 | 858.2 | 918.5
Ceded | (51.0) | (149.3) | (94.5)
Total incurred losses and LAE | 664.0 | 708.9 | 824.0
OneBeacon |  |  |
Written premiums: |  |  |
Direct | 1,193.3 | 1,279.9 | 1,257.5
Assumed | 28.0 | 36.0 | 65.9
Gross written premiums | 1,221.3 | 1,315.9 | 1,323.4
Ceded | (120.6) | (179.3) | (106.5)
Net written premiums | 1,100.7 | 1,136.6 | 1,216.9
Earned premiums: |  |  |
Direct Premiums amount | 1,177.0 | 1,298.0 | 1,209.1
Assumed | 29.4 | 45.9 | 70.9
Gross earned premiums | 1,206.4 | 1,343.9 | 1,280.0
Ceded | (105.8) | (167.7) | (102.9)
Net earned premiums | 1,100.6 | 1,176.2 | 1,177.1
Losses and LAE: |  |  |
Direct | 679.5 | 783.0 | 778.7
Assumed | 21.2 | 55.7 | 115.7
Gross losses and LAE | 700.7 | 838.7 | 894.4
Ceded | (44.7) | (138.0) | (79.3)
Total incurred losses and LAE | 656.0 | 700.7 | 815.1
HG/BAM |  |  |
Written premiums: |  |  |
Direct | 38.6 | 25.9 | 16.2
Assumed | 0.0 | 0.0 | 0.0
Gross written premiums | 38.6 | 25.9 | 16.2
Ceded | 0.0 | 0.0 | 0.0
Net written premiums | 38.6 | 25.9 | 16.2
Earned premiums: |  |  |
Direct Premiums amount | 5.9 | 3.3 | 1.8
Assumed | 0.0 | 0.0 | 0.0
Gross earned premiums | 5.9 | 3.3 | 1.8
Ceded | 0.0 | 0.0 | 0.0
Net earned premiums | 5.9 | 3.3 | 1.8
Losses and LAE: |  |  |
Direct | 0.0 | 0.0 | 0.0
Assumed | 0.0 | 0.0 | 0.0
Gross losses and LAE | 0.0 | 0.0 | 0.0
Ceded | 0.0 | 0.0 | 0.0
Total incurred losses and LAE | 0.0 | 0.0 | 0.0
HG/BAM [Member] |  |  |
Written premiums: |  |  |
Ceded | 27.2 | 19.3 | 12.3
Earned premiums: |  |  |
Ceded | 21.0 | 16.0 | 1.4
Other Segments |  |  |
Written premiums: |  |  |
Direct | 13.3 | 19.9 | 22.6
Assumed | 0.0 | 0.0 | 0.0
Gross written premiums | 13.3 | 19.9 | 22.6
Ceded | (6.8) | (9.8) | (16.7)
Net written premiums | 6.5 | 10.1 | 5.9
Earned premiums: |  |  |
Direct Premiums amount | 15.2 | 20.7 | 22.6
Assumed | 0.0 | 0.0 | 0.0
Gross earned premiums | 15.2 | 20.7 | 22.6
Ceded | (7.7) | (12.0) | (16.5)
Net earned premiums | 7.5 | 8.7 | 6.1
Losses and LAE: |  |  |
Direct | 14.3 | 19.5 | 24.1
Assumed | 0.0 | 0.0 | 0.0
Gross losses and LAE | 14.3 | 19.5 | 24.1
Ceded | (6.3) | (11.3) | (15.2)
Total incurred losses and LAE | $ 8.0 | 8.2 | 8.9
AMTrust [Member] |  |  |
Written premiums: |  |  |
Ceded |  | 33.3 |
Earned premiums: |  |  |
Ceded |  | 33.3 |
Losses and LAE: |  |  |
Ceded |  | $ 33.4 |
Percentage of quota share reinsurance agreement |  | 100.00% |
Star & Shield Insurance Exchange [Member] |  |  |
Written premiums: |  |  |
Ceded |  |  | 16.0
Earned premiums: |  |  |
Ceded |  |  | 15.7
Losses and LAE: |  |  |
Ceded |  |  | $ 16.9

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