Credit Quality of Mortgage Loans by Type of Property (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Mortgage loans on real estate	$ 47,278	$ 52,644
Less: general reserve	(27)	(25)
Total mortgage loans on real estate, net	47,251	52,619
AAA - AA
Financing Receivable, Recorded Investment [Line Items]
Mortgage loans on real estate	17,024	20,821
A
Financing Receivable, Recorded Investment [Line Items]
Mortgage loans on real estate	20,593	31,823
BBB
Financing Receivable, Recorded Investment [Line Items]
Mortgage loans on real estate	$ 9,661

Amount of reserve for write-down of a mortgage loan on real estate.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 10

-Section S99

-Paragraph 6

-Subparagraph (SX 210.5-04.(c) Schedule IV)

-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 29

-Article 12

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

-Subparagraph Schedule IV

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 310

-Section S99

-Paragraph 1

-Subparagraph (SX 210.12-29.7)

-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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