Difference between Fair Value Option and Unpaid Principal Balance (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value Carrying Amount	$ 351,467	$ 201,012
Aggregate Unpaid Principal	341,245	194,692
Fair Value Carrying Amount Less Aggregate Unpaid Principal	$ 10,222	$ 6,320

This item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of loans and long-term receivables (other than securities categorized as trading, available-for-sale or held-to-maturity) that have contractual principal amounts and for which the fair value option has been elected.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 28

-Subparagraph (d)(1)

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

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