Subsequent Events - Additional Information (Detail) (Residential Loans, USD $) In Millions, unless otherwise specified		1 Months Ended
Sep. 30, 2013	Nov. 04, 2013 Subsequent Event
Subsequent Events [Line Items]
Amount of loans planned to be purchased	$ 595
Residential mortgage loans closed and purchased		$ 246

The cash outflow used to purchase loans that are secured with real estate mortgage and are held with the intention to resell in the near future.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 21

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3461-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 230

-Section 55

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6587932&loc=d3e60097-112785

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3367-108585

Name:	us-gaap_PaymentsToPurchaseMortgageLoansHeldForSale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration