Assets Acquired in FDIC-Assisted Acquisitions - Components of Covered Assets (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Covered Assets [Line Items]
Covered loans	$ 414,855	$ 443,322	$ 575,966
Less: Credit risk adjustments	41,978	52,855	114,699
Less: Liquidity and rate adjustments	183	230	543
Total covered loans	372,694	390,237	460,724
OREO	52,092	55,827	91,677
Less: Fair value adjustments	9,456	9,934	13,762
Total covered OREO	42,636	45,893	77,915
Total covered assets	415,330	436,130	538,639
FDIC indemnification asset	53,181	65,441	160,979	159,724
American United Bank (AUB) [Member]
Covered Assets [Line Items]
Covered loans	13,629	15,787	25,001
Less: Credit risk adjustments	220	231	2,508
Total covered loans	13,409	15,556	22,493
OREO	4,264	4,264	8,079
Less: Fair value adjustments			100
Total covered OREO	4,264	4,264	7,979
Total covered assets	17,673	19,820	30,472
FDIC indemnification asset	1,190	1,452	4,176
United Security Bank (USB) [Member]
Covered Assets [Line Items]
Covered loans	15,668	18,504	25,921
Less: Credit risk adjustments	935	1,427	3,879
Total covered loans	14,733	17,077	22,042
OREO	3,366	2,865	5,379
Less: Fair value adjustments	135	141	139
Total covered OREO	3,231	2,724	5,240
Total covered assets	17,964	19,801	27,282
FDIC indemnification asset	535	889	9,932
Satilla Community Bank (SCB) [Member]
Covered Assets [Line Items]
Covered loans	33,896	34,637	40,008
Less: Credit risk adjustments	1,274	1,483	3,189
Total covered loans	32,622	33,154	36,819
OREO	3,122	3,461	6,670
Less: Fair value adjustments	303	303	299
Total covered OREO	2,819	3,158	6,371
Total covered assets	35,441	36,312	43,190
FDIC indemnification asset	2,781	3,175	8,189
First Bank of Jacksonville (FBJ) [Member]
Covered Assets [Line Items]
Covered loans	24,281	25,891	31,479
Less: Credit risk adjustments	2,768	3,730	5,662
Less: Liquidity and rate adjustments			11
Total covered loans	21,513	22,161	25,806
OREO	1,850	1,880	1,450
Less: Fair value adjustments	253	242	93
Total covered OREO	1,597	1,638	1,357
Total covered assets	23,110	23,799	27,163
FDIC indemnification asset	3,034	3,689	6,840
Darby Bank & Trust (DBT) [Member]
Covered Assets [Line Items]
Covered loans	100,909	105,157	146,178
Less: Credit risk adjustments	13,138	17,819	35,461
Less: Liquidity and rate adjustments			83
Total covered loans	87,771	87,338	110,634
OREO	12,250	17,023	25,990
Less: Fair value adjustments	1,092	1,282	1,895
Total covered OREO	11,158	15,741	24,095
Total covered assets	98,929	103,079	134,729
FDIC indemnification asset	14,947	18,724	37,333
Tifton Banking Company (TBC) [Member]
Covered Assets [Line Items]
Covered loans	31,576	32,590	42,302
Less: Credit risk adjustments	2,119	2,340	4,450
Less: Liquidity and rate adjustments		14	133
Total covered loans	29,457	30,236	37,719
OREO	4,681	4,844	10,478
Less: Fair value adjustments	761	745	1,814
Total covered OREO	3,920	4,099	8,664
Total covered assets	33,377	34,335	46,383
FDIC indemnification asset	3,425	3,721	8,050
High Trust Bank (HTB) [Member]
Covered Assets [Line Items]
Covered loans	61,560	67,126	82,202
Less: Credit risk adjustments	6,596	7,321	14,068
Less: Liquidity and rate adjustments	34	38	49
Total covered loans	54,930	59,767	68,085
OREO	7,263	6,374	14,823
Less: Fair value adjustments	2,349	2,304	3,445
Total covered OREO	4,914	4,070	11,378
Total covered assets	59,844	63,837	79,463
FDIC indemnification asset	8,540	9,325	21,423
One Georgia Bank (OGB) [Member]
Covered Assets [Line Items]
Covered loans	55,569	58,512	73,279
Less: Credit risk adjustments	4,564	4,969	14,877
Less: Liquidity and rate adjustments	89	98	127
Total covered loans	50,916	53,445	58,275
OREO	8,169	7,506	10,384
Less: Fair value adjustments	2,984	2,984	4,144
Total covered OREO	5,185	4,522	6,240
Total covered assets	56,101	57,967	64,515
FDIC indemnification asset	6,815	9,645	18,687
Central Bank of Georgia (CBG) [Member]
Covered Assets [Line Items]
Covered loans	77,767	85,118	109,596
Less: Credit risk adjustments	10,364	13,535	30,605
Less: Liquidity and rate adjustments	60	80	140
Total covered loans	67,343	71,503	78,851
OREO	7,127	7,610	8,424
Less: Fair value adjustments	1,579	1,933	1,833
Total covered OREO	5,548	5,677	6,591
Total covered assets	72,891	77,180	85,442
FDIC indemnification asset	$ 11,914	$ 14,821	$ 46,349