Allowance for Loan Losses - Transactions in Allowance for loan Losses (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Allowance for Loan Losses:
Beginning Balance	$ 8,835	$ 8,048	$ 8,857	$ 8,136
Charge-offs	(335)	(2,608)	(932)	(3,293)
Recoveries	112	13	148	70
Provision	3,538	1,290	4,077	1,830
Ending Balance	12,150	6,743	12,150	6,743
Individually evaluated for impairment	7,655	2,277	7,655	2,277
Collectively evaluated for impairment	4,495	4,466	4,495	4,466
Individually evaluated for impairment, Total	82,499	95,284	82,499	95,284
Collectively evaluated for impairment, Total	320,599	332,307	320,599	332,307
Gaming [Member]
Allowance for Loan Losses:
Beginning Balance	1,146	632	1,541	457
Charge-offs		(275)	(474)	(275)
Provision	(160)	117	(81)	292
Ending Balance	986	474	986	474
Individually evaluated for impairment	626		626
Collectively evaluated for impairment	360	474	360	474
Individually evaluated for impairment, Total	21,579	25,010	21,579	25,010
Collectively evaluated for impairment, Total	28,758	34,287	28,758	34,287
Residential and land development [Member]
Allowance for Loan Losses:
Beginning Balance	238	1,041	200	1,081
Charge-offs		(1,103)		(1,103)
Recoveries	67		67
Provision	3,038	265	3,076	225
Ending Balance	3,343	203	3,343	203
Individually evaluated for impairment	3,143		3,143
Collectively evaluated for impairment	200	203	200	203
Individually evaluated for impairment, Total	20,974	21,339	20,974	21,339
Collectively evaluated for impairment, Total	6,109	6,292	6,109	6,292
Real estate, construction [Member]
Allowance for Loan Losses:
Beginning Balance	935	496	967	937
Charge-offs	(47)		(47)	(474)
Provision	442	(47)	410	(14)
Ending Balance	1,330	449	1,330	449
Individually evaluated for impairment	1,302	401	1,302	401
Collectively evaluated for impairment	28	48	28	48
Individually evaluated for impairment, Total	7,794	9,572	7,794	9,572
Collectively evaluated for impairment, Total	42,153	44,258	42,153	44,258
Real estate, mortgage [Member]
Allowance for Loan Losses:
Beginning Balance	5,551	5,016	5,273	4,800
Charge-offs	(223)	(1,003)	(281)	(1,102)
Recoveries	1		2
Provision	259	863	594	1,178
Ending Balance	5,588	4,876	5,588	4,876
Individually evaluated for impairment	2,220	1,605	2,220	1,605
Collectively evaluated for impairment	3,368	3,271	3,368	3,271
Individually evaluated for impairment, Total	29,759	36,462	29,759	36,462
Collectively evaluated for impairment, Total	203,399	209,500	203,399	209,500
Commercial and Industrial [Member]
Allowance for Loan Losses:
Beginning Balance	667	547	593	557
Charge-offs		(101)		(160)
Recoveries	11	4	22	14
Provision	(51)	7	12	46
Ending Balance	627	457	627	457
Individually evaluated for impairment	331	236	331	236
Collectively evaluated for impairment	296	221	296	221
Individually evaluated for impairment, Total	2,320	2,772	2,320	2,772
Collectively evaluated for impairment, Total	32,019	28,075	32,019	28,075
Other [Member]
Allowance for Loan Losses:
Beginning Balance	298	316	283	304
Charge-offs	(65)	(126)	(130)	(179)
Recoveries	33	9	57	56
Provision	10	85	66	103
Ending Balance	276	284	276	284
Individually evaluated for impairment	33	35	33	35
Collectively evaluated for impairment	243	249	243	249
Individually evaluated for impairment, Total	73	129	73	129
Collectively evaluated for impairment, Total	$ 8,161	$ 9,895	$ 8,161	$ 9,895