Variable Contracts Containing Guaranteed Benefits - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Future policy benefits	$ 552,500	$ 518,911
GMDB
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Future policy benefits	135,787	131,378
GMIB
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Future policy benefits	$ 105,587	$ 95,048

Amount of accrued obligation to policyholders that relates to insured events for long-duration contracts.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 25
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=28366191&loc=d3e13145-158430

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (cc)
-URI http://asc.fasb.org/extlink&oid=65670824&loc=d3e14764-158437

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.13(a)(1))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=65670824&loc=d3e14764-158437

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant