Realized Gains and Losses, Excluding Net Other-Than-Temporary Impairment Losses Recognized in Earnings (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Gain (Loss) on Investments [Line Items]
Net Realized Gains (Losses)	$ 1,694	$ 1,960	$ 2,743	$ 3,557
Fixed Maturities
Gain (Loss) on Investments [Line Items]
Gains	344	1,296	812	3,844
Losses	(958)	(738)	(2,214)	(1,865)
Net Realized Gains (Losses)	(614)	558	(1,402)	1,979
Short-Term Investments
Gain (Loss) on Investments [Line Items]
Gains	135	407	247	675
Losses	(69)	(60)	(260)	(143)
Net Realized Gains (Losses)	66	347	(13)	532
Equity Securities
Gain (Loss) on Investments [Line Items]
Gains	2,470	1,071	4,386	1,680
Losses	(228)	(16)	(228)	(634)
Net Realized Gains (Losses)	$ 2,242	$ 1,055	$ 4,158	$ 1,046

This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563

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This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26805-111562

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Amount of loss realized on the sale of debt or equity securities classified as available-for-sale. Excludes other than temporary impairments (OTTI).

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