Delinquency Statistics of Commercial Real Estate Loan (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Mortgage Loans on Real Estate [Line Items]
Delinquency statistics, Total	$ 47,427	$ 53,735
30 to 59 days
Mortgage Loans on Real Estate [Line Items]
Delinquency statistics, Total	963	1,974
60 to 89 days
Mortgage Loans on Real Estate [Line Items]
Delinquency statistics, Total	5,211	5,211
90 days or more
Mortgage Loans on Real Estate [Line Items]
Delinquency statistics, Total	24,556	37,130
In foreclosure or bankruptcy proceedings
Mortgage Loans on Real Estate [Line Items]
Delinquency statistics, Total	$ 16,697	$ 9,420

Amount of principal due on loans that have been delinquent, which may exclude loans having interest delinquent for three months or less, as of the balance sheet date.

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 210.12-29.10(a))

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

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Data Type:	xbrli:monetaryItemType
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