Loans and Other Repossessed Assets Acquired (Detail) - Schedule of impaired loans (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Unpaid Contractual Principal Balance	$ 44,308	$ 31,226
Recorded Investment With No Specific Allowance	30,208	20,820
Recorded Investment With Specific Allowance	4,619	4,774
Total Recorded Investment	34,827	25,594
Specific Allowance	1,325	962
Average Balance	30,212	25,832
Interest Income Recognized Period to Date	47	186
Residential Mortgage [Member] | Residential 1-4 Family [Member]
Unpaid Contractual Principal Balance	7,734	2,123
Recorded Investment With No Specific Allowance	5,705	1,988
Recorded Investment With Specific Allowance	462	0
Total Recorded Investment	6,167	1,988
Specific Allowance	93	0
Average Balance	4,078	2,117
Interest Income Recognized Period to Date	0	0
Residential Mortgage [Member] | Residential Land [Member]
Unpaid Contractual Principal Balance	675	341
Recorded Investment With No Specific Allowance	314	62
Recorded Investment With Specific Allowance	16	0
Total Recorded Investment	330	62
Specific Allowance	5	0
Average Balance	196	31
Interest Income Recognized Period to Date	4	0
Residential Mortgage [Member]
Unpaid Contractual Principal Balance	8,409	2,464
Recorded Investment With No Specific Allowance	6,019	2,050
Recorded Investment With Specific Allowance	478	0
Total Recorded Investment	6,497	2,050
Specific Allowance	98	0
Average Balance	4,274	2,148
Interest Income Recognized Period to Date	4	0
Commercial Loan [Member] | Commercial Business [Member]
Unpaid Contractual Principal Balance	2,025	1,676
Recorded Investment With No Specific Allowance	1,180	1,368
Recorded Investment With Specific Allowance	829	108
Total Recorded Investment	2,009	1,476
Specific Allowance	829	0
Average Balance	1,743	2,565
Interest Income Recognized Period to Date	9	33
Commercial Loan [Member] | Commercial Real Estate [Member]
Unpaid Contractual Principal Balance	16,883	13,510
Recorded Investment With No Specific Allowance	12,024	8,595
Recorded Investment With Specific Allowance	1,726	3,324
Total Recorded Investment	13,750	11,919
Specific Allowance	109	624
Average Balance	12,835	12,096
Interest Income Recognized Period to Date	28	0
Commercial Loan [Member] | Commercial Construction [Member]
Unpaid Contractual Principal Balance	0	311
Recorded Investment With No Specific Allowance	0	247
Recorded Investment With Specific Allowance	0	0
Total Recorded Investment	0	247
Specific Allowance	0	0
Average Balance	124	254
Interest Income Recognized Period to Date	0	125
Commercial Loan [Member] | Commercial Land [Member]
Unpaid Contractual Principal Balance	5,361	5,000
Recorded Investment With No Specific Allowance	2,426	2,121
Recorded Investment With Specific Allowance	1,040	1,243
Total Recorded Investment	3,466	3,364
Specific Allowance	230	271
Average Balance	3,415	3,546
Interest Income Recognized Period to Date	0	0
Commercial Loan [Member]
Unpaid Contractual Principal Balance	24,269	20,497
Recorded Investment With No Specific Allowance	15,630	12,331
Recorded Investment With Specific Allowance	3,595	4,675
Total Recorded Investment	19,225	17,006
Specific Allowance	1,168	895
Average Balance	18,116	18,461
Interest Income Recognized Period to Date	37	158
Consumer Loan [Member] | Home Equity Loans [Member]
Unpaid Contractual Principal Balance	11,013	8,070
Recorded Investment With No Specific Allowance	8,281	6,262
Recorded Investment With Specific Allowance	447	99
Total Recorded Investment	8,728	6,361
Specific Allowance	43	67
Average Balance	7,545	5,068
Interest Income Recognized Period to Date	6	28
Consumer Loan [Member] | Manufactured Housing [Member]
Unpaid Contractual Principal Balance	605	195
Recorded Investment With No Specific Allowance	273	177
Recorded Investment With Specific Allowance	99	0
Total Recorded Investment	372	177
Specific Allowance	16	0
Average Balance	275	155
Interest Income Recognized Period to Date	0	0
Consumer Loan [Member] | Marine [Member]
Unpaid Contractual Principal Balance	12	0
Recorded Investment With No Specific Allowance	5	0
Recorded Investment With Specific Allowance	0	0
Total Recorded Investment	5	0
Specific Allowance	0	0
Average Balance	3	0
Interest Income Recognized Period to Date	0	0
Consumer Loan [Member]
Unpaid Contractual Principal Balance	11,630	8,265
Recorded Investment With No Specific Allowance	8,559	6,439
Recorded Investment With Specific Allowance	546	99
Total Recorded Investment	9,105	6,538
Specific Allowance	59	67
Average Balance	7,822	5,223
Interest Income Recognized Period to Date	6	28
Acquired Non-Covered Loans [Member]
Unpaid Contractual Principal Balance	299	0
Recorded Investment With No Specific Allowance	154	0
Recorded Investment With Specific Allowance	0	0
Total Recorded Investment	154	0
Specific Allowance	0	0
Average Balance	77	0
Interest Income Recognized Period to Date	0	0
Acquired Covered Loans [Member]
Unpaid Contractual Principal Balance	6,379	4,228
Recorded Investment With No Specific Allowance	4,181	3,217
Recorded Investment With Specific Allowance	719	300
Total Recorded Investment	4,900	3,517
Specific Allowance	42	12
Average Balance	4,209	8,082
Interest Income Recognized Period to Date	0	0
Legacy Loans [Member]
Unpaid Contractual Principal Balance	37,630	26,998
Recorded Investment With No Specific Allowance	25,873	17,603
Recorded Investment With Specific Allowance	3,900	4,474
Total Recorded Investment	29,773	22,077
Specific Allowance	1,283	950
Average Balance	25,926	17,750
Interest Income Recognized Period to Date	$ 47	$ 186