Losses and Loss Adjustment Reserve - Effects of Reinsurance on Premiums Written and Earned (Detail) $ in Thousands	6 Months Ended
Jun. 30, 2018 USD ($)
Written
Direct premiums	$ 283,974
Ceded premiums	(283,967)
Net premiums	7
Earned
Direct premiums	294,284
Ceded premiums	(294,277)
Net premiums	$ 7

Amount of earned premiums ceded to other entities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.1)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

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-URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547

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-Name Accounting Standards Codification
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Amount of written premiums ceded to other entities.

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547

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-Subparagraph (SX 210.12-17)
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

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Amount, before premiums ceded to other entities and premiums assumed by the entity, of premiums written.

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

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