Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6351-108592

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- Definition

Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 50
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-URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6824-158387

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-Publisher FASB
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-Section S99
-Paragraph 1
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- Definition

Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
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Reinsurance (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
Reinsurance (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Ceded Credit Risk [Line Items]
Reinsurance recoverable	$ 1,572,321	$ 325,819	$ 1,586,630
Allowance for reinsurance recoverable
Ceded Credit Risk [Line Items]
Valuation allowances and reserves balance	$ 7,800		$ 7,000
Customer Concentration Risk, Customer One \| Reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	9.30%	10.40%
Customer Concentration Risk, Customer One \| Allowance for reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	16.10%	11.10%
Customer Concentration Risk, Customer Two \| Reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	8.10%	7.50%
Customer Concentration Risk, Customer Two \| Allowance for reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	15.20%	9.20%
Customer Concentration Risk, Customer Three \| Reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	6.70%	7.30%
Customer Concentration Risk, Customer Three \| Allowance for reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	14.20%	8.40%
Ceded Credit Risk, Secured \| Reinsurer Concentration Risk \| Reinsurance recoverable
Ceded Credit Risk [Line Items]
Concentration risk, percentage	52.20%	54.50%
Ceded Credit Risk, Unsecured \| Reinsurer Concentration Risk \| Reinsurance recoverable \| Standard & Poor's, A- Rating
Ceded Credit Risk [Line Items]
Concentration risk, percentage	46.80%	44.50%
Ceded Credit Risk, Unsecured \| Reinsurer Concentration Risk \| Reinsurance recoverable \| Standard & Poor's, BBB Rating
Ceded Credit Risk [Line Items]
Concentration risk, percentage	1.00%	1.00%