Subsidiary Dividend Restrictions - Additional Information (Detail) - Wright Flood - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2016
Dividend Restrictions [Line Items]
Dividend rate as a percentage of net income	100.00%
Ordinary dividends payment description	The maximum amount of ordinary dividends that Wright Flood can pay to shareholders in a rolling twelve month period is limited to the greater of 10% of statutory adjusted capital and surplus as shown on Wright Flood’s last annual statement on file with the superintendent or 100% of adjusted net income.
Scenario, Forecast
Dividend Restrictions [Line Items]
Maximum dividend payout that may be made without prior approval		$ 4.1
Maximum
Dividend Restrictions [Line Items]
Dividend rate as a percentage of net income	10.00%

[Line Items] for Dividend Restrictions [Table]

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- Definition

Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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- Definition

Amount of dividends that can be declared or paid without approval of regulatory agency.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph e
-Article 4

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- Definition

Disclosure of statutory restrictions on the payment of dividends as prescribed by the National Association of Insurance Commissioners or state regulatory authorities, amounts not available for future dividend payments, and amount of dividends paid.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6486098&loc=d3e24708-158529

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