Assets Acquired and Liabilities Assumed Including Recast Adjustments (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended				12 Months Ended		12 Months Ended				1 Months Ended
	Dec. 31, 2012	Sep. 07, 2012	Jan. 27, 2012	Dec. 31, 2011	Dec. 31, 2012 First Commercial Bank("FCB")	Sep. 07, 2012 First Commercial Bank("FCB")	Dec. 31, 2012 Tennessee Commerce Bank ("TCB")	Jan. 27, 2012 Tennessee Commerce Bank ("TCB")	Sep. 07, 2012 Contractual Amount First Commercial Bank("FCB")	Jan. 27, 2012 Contractual Amount Tennessee Commerce Bank ("TCB")	Sep. 07, 2012 Fair Value Adjustments First Commercial Bank("FCB")	Jan. 27, 2012 Fair Value Adjustments Tennessee Commerce Bank ("TCB")	Sep. 07, 2012 Recast Adjustments First Commercial Bank("FCB")	Jan. 27, 2012 Recast Adjustments Tennessee Commerce Bank ("TCB")	Sep. 07, 2012 Fair Value First Commercial Bank("FCB")	Jan. 27, 2012 Fair Value Tennessee Commerce Bank ("TCB")
Assets acquired :
Cash and cash equivalents									$ 10,524	$ 61,943		$ (89)		$ (2)	$ 10,524	$ 61,852
Securities available for sale					12,000		43,000		12,002	42,646					12,002	42,646
Loans to be repurchased by the FDIC, net of discount								(2,797)		19,800		(2,797)				17,003
Loans						(43,791)		(21,836)	171,744	79,112	(44,214)	(22,666)	423	830	127,953	57,276
Federal Home Loan Bank stock, at cost						79,412		56,970	407	2,491					407	2,491
Other assets and accrued interest receivable						(95)		(60)	829	945	(95)	(60)			734	885
Other real estate owned						(8,100)		(4,472)	19,360	14,189	(8,389)	(3,359)	289	(1,113)	11,260	9,717
Core deposit intangible						559		64			559	64			559	64
Discount						(79,412)		(56,970)	(79,412)	(56,970)	79,412	56,970
FDIC settlement receivable						(64,326)		(784,545)	64,326	784,545					64,326	784,545
Total assets acquired		215,000	221,000			214,866		221,126	199,780	948,701	27,273	28,063	712	(285)	227,765	976,479
Deposits
Non interest-bearing									7,197	19,754					7,197	19,754
Interest-bearing						(3)		54	189,057	927,641	(3)	54			189,054	927,695
Total deposits									196,254	947,395	(3)	54			196,251	947,449
Federal Home Loan Bank advances						63			3,002		63				3,065
Accrued income taxes payable											9,706	9,988	249	(100)	9,955	9,888
Other liabilities and accrued interest payable									524	1,306	101	110			625	1,416
Total liabilities assumed						199,780		948,701	199,780	948,701	9,867	10,152	249	(100)	209,896	958,753
Equity
Bargain purchase gain, net of taxes	55,438				27,824		27,614				17,406	17,911	463	(185)	17,869	17,726
Total liabilities assumed and equity	$ 3,394,399			$ 3,419,991					$ 199,780	$ 948,701	$ 27,273	$ 28,063	$ 712	$ (285)	$ 227,765	$ 976,479