Net Investment Income By Source (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net Investment Income [Line Items]
Gross investment income	$ 29,484	$ 29,623	$ 57,057	$ 60,133
Less investment expenses	(1,870)	(1,207)	(2,991)	(2,190)
Net investment income	27,614	28,416	54,066	57,943
Limited partnership
Net Investment Income [Line Items]
Gross investment income	(90)	429	(2,631)	1,557
Fixed maturity AFS securities
Net Investment Income [Line Items]
Gross investment income	16,863	17,863	34,230	35,924
Policy loans
Net Investment Income [Line Items]
Gross investment income	8,382	8,808	16,991	17,610
Cash and Cash Equivalents
Net Investment Income [Line Items]
Gross investment income	564	162	1,015	308
Equity AFS securities
Net Investment Income [Line Items]
Gross investment income	538	561	1,003	1,031
Mortgage loans on real estate
Net Investment Income [Line Items]
Gross investment income	1,264	937	2,467	1,860
Derivatives
Net Investment Income [Line Items]
Gross investment income	1,857	929	3,769	1,830
Other
Net Investment Income [Line Items]
Gross investment income	$ 106	$ (66)	$ 213	$ 13

Gross Investment Income (Loss) Operating

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Amount, before investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

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Amount of expenses related to the generation of investment income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.9)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.2)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

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Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

+ 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(2))
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-16(Column G))
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574960-122915

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