Fair Value Measurement - Amount of Gains and Losses from Changes in Fair Value Included in Earnings (Detail) (Construction Loans [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015
Construction Loans [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Change in fair value	$ 561
Total change in fair value	$ 561

For loans held as assets for which the fair value option has been elected, this item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of those loans that are 90 days or more past due, in nonaccrual status, or both.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 28

-Subparagraph (e)(3)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

Name:	us-gaap_FairValueOptionLoansHeldAsAssetsAggregateDifference
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant