Fair value and the undiscounted amount of the true-up payment obligation (Detail) (Federal Deposit Insurance Corporation [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Federal Deposit Insurance Corporation [Member]
Business Acquisition, Contingent Consideration [Line Items]
Business Combination Contingent Consideration Liability	$ 126,473	$ 127,513
Business Combination Contingent Consideration Potential Cash Payment	$ 187,636	$ 185,372

Amount of liability recognized arising from contingent consideration in a business combination.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 35

-Paragraph 1

-Subparagraph b

-URI http://asc.fasb.org/extlink&oid=6911338&loc=d3e6819-128478

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 25

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476

Name:	us-gaap_BusinessCombinationContingentConsiderationLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant