Loans and Allowance for Loan Losses - Schedule of Average Net Investment Impaired Loans and Interest Income Recognized and Received on Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Schedule Of Financial Receivables [Line Items]
Average Recorded Investment	$ 45,627	$ 54,220
Interest Income Recognized	1,206	2,529
Interest Income Received	1,199	2,582
Construction, Land Development and Other Land Loans [Member]
Schedule Of Financial Receivables [Line Items]
Average Recorded Investment	11,656	18,283
Interest Income Recognized	134	546
Interest Income Received	135	598
Secured by 1-4 Family Residential Properties [Member]
Schedule Of Financial Receivables [Line Items]
Average Recorded Investment	308	146
Interest Income Recognized	5	10
Interest Income Received	6	10
Secured by Multi-family Residential Properties [Member]
Schedule Of Financial Receivables [Line Items]
Average Recorded Investment	9,075	4,942
Interest Income Recognized	298	483
Interest Income Received	304	455
Secured by Non-farm, Non-residential Properties [Member]
Schedule Of Financial Receivables [Line Items]
Average Recorded Investment	23,527	29,627
Interest Income Recognized	741	1,452
Interest Income Received	726	1,477
Commercial and Industrial Loans [Member]
Schedule Of Financial Receivables [Line Items]
Average Recorded Investment	1,061	1,222
Interest Income Recognized	28	38
Interest Income Received	$ 28	$ 42