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Reinsurance - Schedule of the Effect of Reinsurance on Premiums Written and Earned (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Premiums Written and Earned [Abstract]
Gross Written									$ 386,529	$ 393,819	$ 372,177
Ceded Written									(11,228)	(13,793)	(18,425)
Net premiums Written									375,301	380,026	353,752
Gross Earned									387,122	389,540	348,408
Ceded Earned									(11,228)	(13,793)	(18,425)
Net premiums Earned	$ 95,034	$ 90,504	$ 95,569	$ 94,787	$ 97,070	$ 95,928	$ 93,516	$ 89,233	$ 375,894	$ 375,747	$ 329,983

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Amount, before premiums ceded to other entities of premiums earned.

+ References

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Amount of earned premiums ceded to other entities.

+ References

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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-SubTopic 605
-Section 50
-Paragraph 1
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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.

+ References

Reference 1: 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 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 17
-Article 12

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

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Amount of direct and assumed premiums written.

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+ References

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