Losses and Loss Adjustment Reserve - Effects of Reinsurance on Premiums Written and Earned (Detail) $ in Thousands	3 Months Ended
Mar. 31, 2018 USD ($)
Written
Direct premiums	$ 116,490
Ceded premiums	(116,487)
Net premiums	3
Earned
Direct premiums	145,336
Ceded premiums	(145,333)
Net premiums	$ 3

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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-Section 50
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-URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547

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

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-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

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

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