Mergers and Acquisitions (Details) (USD $) In Thousands, except Share data, unless otherwise specified	2 Months Ended	0 Months Ended
	Apr. 30, 2012	Sep. 01, 2013		Sep. 01, 2013		Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 10, 2014 Branches	Jan. 20, 2015	Aug. 31, 2011 Trust	Feb. 04, 2011 Branches	Jul. 23, 2010 Branches
Business Acquisition [Line Items]
Goodwill resulting from merger						$ 274,705	$ 274,706	$ 276,144
Variable interest rate of derivatives, description	the three-month LIBOR plus a pre-determined spread
Eligible losses covered (percent)						80.00%
Eligible recoveries covered (percent)						80.00%
Heritage Financial Group
Business Acquisition [Line Items]
Total assets									1,807,828
Loans acquired									1,104,261
Deposits assumed									1,394,111
Number of banking, mortgage, and investment offices (branches)									48
Heritage Financial Group | Norcross, Georgia
Business Acquisition [Line Items]
Loans acquired										37,000
Deposits assumed										107,000
First M&F Merger
Business Acquisition [Line Items]
Total assets		1,516,603		1,516,603
Number of banking and insurance locations the entity operates (branches)		43		43
Shares issued to common shareholders (shares)		6,175,576
Voting interest acquired (percent)		100.00%		100.00%
Total Purchase Price		156,845
Intangible assets, including goodwill		115,159		115,159
Goodwill resulting from merger		90,127	[1]	90,127	[1]
Borrowings		25,346		25,346
First M&F Merger | Core Deposits
Business Acquisition [Line Items]
Intangible assets, other than goodwill		25,032		25,032
Weighted average useful life				10 years
First M&F Merger | Junior Subordinated Debt
Business Acquisition [Line Items]
Borrowings		30,928		30,928
Variable interest rate of derivatives, description				90-day LIBOR
Fair value adjustment				12,371
First M&F Merger | LIBOR | Junior Subordinated Debt
Business Acquisition [Line Items]
Basis spread on variable rate (percent)				1.33%
First M&F Merger | Common Stock
Business Acquisition [Line Items]
Shares issued to common shareholders (shares)		6,175,576
Royal Bank Client
Business Acquisition [Line Items]
Assets under management											680,000
Trust transferred under acquisition (trust)											200
American Trust Bank
Business Acquisition [Line Items]
Number of branches in the northwest region of Georgia (branches)												3
Value of loans covered in loss-share agreements with the FDIC												73,657
Eligible losses covered (percent)						80.00%
Eligible recoveries covered (percent)						80.00%
Crescent Bank & Trust Company
Business Acquisition [Line Items]
Number of branches in the northwest region of Georgia (branches)													11
Value of loans covered in loss-share agreements with the FDIC													361,472
Value Of Other Real Estate Owned Covered In Loss Share Agreements With Federal Deposit Insurance Corporation													$ 50,168
Eligible losses covered (percent)						80.00%

[1] The goodwill resulting from the merger has been assigned to the Community Banks operating segment.