Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums earned.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
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-Subparagraph (SX 210.7-04.1)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 605
-Section 50
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-URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(c))
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-Name Accounting Standards Codification
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-Subparagraph (SX 210.12-17)
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Schedule IV. Supplemental Schedule of Reinsurance Premiums (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Schedule of Reinsurance Premiums for Insurance Companies [Abstract]
Gross Amounts									$ 244,285	$ 157,112	$ 98,182
Ceded to Other Companies									833,929	628,675	466,719
Assumed									2,307,219	1,874,993	1,769,088
Net premiums earned (Note 7)	$ 421,473	$ 547,792	$ 382,265	$ 366,045	$ 351,901	$ 346,521	$ 351,402	$ 353,606	$ 1,717,575	$ 1,403,430	$ 1,400,551
Percentage of Amount Assumed to Net									134.00%	134.00%	126.00%