Loans - Age Analysis of Loan Portfolio, Segregated by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of Days Past Due, 30-59	$ 6,244	$ 12,226	$ 17,932
Number of Days Past Due, 60-89	3,203	2,689	5,406
Number of Days Past Due, Greater Than 90	19,418	28,158	19,629
Number of Days Past Due, Total Past Due	28,865	43,073	42,967
Current	333,542	332,276	388,116
Total	362,407	375,349	431,083
Loans Past Due Greater Than 90 Days and Still Accruing	763	651	1,445
Gaming [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of Days Past Due, 60-89			1,721
Number of Days Past Due, Total Past Due			1,721
Current	31,353	29,570	58,466
Total	31,353	29,570	60,187
Residential and Land Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of Days Past Due, 30-59		51
Number of Days Past Due, Greater Than 90	5,262	13,572	5,765
Number of Days Past Due, Total Past Due	5,262	13,623	5,765
Current	4,857	5,780	21,573
Total	10,119	19,403	27,338
Real Estate, Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of Days Past Due, 30-59	1,665	3,846	3,989
Number of Days Past Due, 60-89	85		878
Number of Days Past Due, Greater Than 90	1,944	9,452	6,151
Number of Days Past Due, Total Past Due	3,694	13,298	11,018
Current	30,316	31,689	41,568
Total	34,010	44,987	52,586
Loans Past Due Greater Than 90 Days and Still Accruing	30	146	572
Real Estate, Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of Days Past Due, 30-59	3,502	6,910	12,012
Number of Days Past Due, 60-89	3,101	2,684	2,702
Number of Days Past Due, Greater Than 90	12,007	5,134	7,605
Number of Days Past Due, Total Past Due	18,610	14,728	22,319
Current	221,731	222,430	224,101
Total	240,341	237,158	246,420
Loans Past Due Greater Than 90 Days and Still Accruing	733	505	872
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of Days Past Due, 30-59	909	1,192	1,804
Number of Days Past Due, 60-89	7		79
Number of Days Past Due, Greater Than 90	205		107
Number of Days Past Due, Total Past Due	1,121	1,192	1,990
Current	30,785	33,815	33,014
Total	31,906	35,007	35,004
Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of Days Past Due, 30-59	168	227	127
Number of Days Past Due, 60-89	10	5	26
Number of Days Past Due, Greater Than 90			1
Number of Days Past Due, Total Past Due	178	232	154
Current	14,500	8,992	9,394
Total	14,678	9,224	9,548
Loans Past Due Greater Than 90 Days and Still Accruing			$ 1