Assets Acquired in FDIC-Assisted Acquisitions - Components of Covered Assets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Covered Assets [Line Items]
Covered loans	$ 443,322	$ 641,451
Less: Credit risk adjustments	52,855	132,983
Less: Liquidity and rate adjustments	230	756
Total covered loans	390,237	507,712
OREO	55,827	105,347
Less: Fair value adjustments	9,934	17,074
Total covered OREO	45,893	88,273
Total covered assets	436,130	595,985
FDIC indemnification asset	65,441	159,724
American United Bank (AUB) [Member]
Covered Assets [Line Items]
Covered loans	15,787	27,169
Less: Credit risk adjustments	231	2,481
Total covered loans	15,556	24,688
OREO	4,264	10,636
Less: Fair value adjustments		102
Total covered OREO	4,264	10,534
Total covered assets	19,820	35,222
FDIC indemnification asset	1,452	2,905
United Security Bank (USB) [Member]
Covered Assets [Line Items]
Covered loans	18,504	27,286
Less: Credit risk adjustments	1,427	4,320
Total covered loans	17,077	22,966
OREO	2,865	7,087
Less: Fair value adjustments	141	99
Total covered OREO	2,724	6,988
Total covered assets	19,801	29,954
FDIC indemnification asset	889	6,619
Satilla Community Bank (SCB) [Member]
Covered Assets [Line Items]
Covered loans	34,637	41,389
Less: Credit risk adjustments	1,483	3,285
Total covered loans	33,154	38,104
OREO	3,461	10,686
Less: Fair value adjustments	303	654
Total covered OREO	3,158	10,032
Total covered assets	36,312	48,136
FDIC indemnification asset	3,175	6,133
First Bank of Jacksonville (FBJ) [Member]
Covered Assets [Line Items]
Covered loans	25,891	32,574
Less: Credit risk adjustments	3,730	6,204
Less: Liquidity and rate adjustments		27
Total covered loans	22,161	26,343
OREO	1,880	3,260
Less: Fair value adjustments	242	526
Total covered OREO	1,638	2,734
Total covered assets	23,799	29,077
FDIC indemnification asset	3,689	6,589
Darby Bank & Trust (DBT) [Member]
Covered Assets [Line Items]
Covered loans	105,157	169,527
Less: Credit risk adjustments	17,819	41,631
Less: Liquidity and rate adjustments		207
Total covered loans	87,338	127,689
OREO	17,023	30,395
Less: Fair value adjustments	1,282	2,160
Total covered OREO	15,741	28,235
Total covered assets	103,079	155,924
FDIC indemnification asset	18,724	47,012
Tifton Banking Company (TBC) [Member]
Covered Assets [Line Items]
Covered loans	32,590	46,796
Less: Credit risk adjustments	2,340	4,979
Less: Liquidity and rate adjustments	14	173
Total covered loans	30,236	41,644
OREO	4,844	11,089
Less: Fair value adjustments	745	1,381
Total covered OREO	4,099	9,708
Total covered assets	34,335	51,352
FDIC indemnification asset	3,721	8,073
High Trust Bank (HTB) [Member]
Covered Assets [Line Items]
Covered loans	67,126	90,602
Less: Credit risk adjustments	7,321	16,072
Less: Liquidity and rate adjustments	38	52
Total covered loans	59,767	74,478
OREO	6,374	13,980
Less: Fair value adjustments	2,304	4,954
Total covered OREO	4,070	9,026
Total covered assets	63,837	83,504
FDIC indemnification asset	9,325	20,020
One Georgia Bank (OGB) [Member]
Covered Assets [Line Items]
Covered loans	58,512	81,908
Less: Credit risk adjustments	4,969	17,127
Less: Liquidity and rate adjustments	98	136
Total covered loans	53,445	64,645
OREO	7,506	9,168
Less: Fair value adjustments	2,984	4,078
Total covered OREO	4,522	5,090
Total covered assets	57,967	69,735
FDIC indemnification asset	9,645	16,871
Central Bank of Georgia (CBG) [Member]
Covered Assets [Line Items]
Covered loans	85,118	124,200
Less: Credit risk adjustments	13,535	36,884
Less: Liquidity and rate adjustments	80	161
Total covered loans	71,503	87,155
OREO	7,610	9,046
Less: Fair value adjustments	1,933	3,120
Total covered OREO	5,677	5,926
Total covered assets	77,180	93,081
FDIC indemnification asset	$ 14,821	$ 45,502