Business Combinations (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013 Somerville Bank & Trust Company [Member] Branch	Jul. 26, 2013 Oxford, Mississippi Branches [Member] Branch
Business Acquisition [Line Items]
Number of branches acquired			5	2
Total assets	$ 0	$ 1,845,930	$ 219,600
Business acquisition purchase price allocation deposits acquired				$ 11,700

Amount of other liabilities due within one year or within the normal operating cycle, if longer, assumed at the acquisition date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6910749&loc=d3e4845-128472

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