Loans and Other Repossessed Assets Acquired (Detail) - Troubled debt restructurings (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
#	63		54
Accruing	$ 3,768		$ 3,536
Non-accruing	12,328		13,169
Total	16,096	[1]	16,705	[1]
Residential Mortgage [Member] | Residential 1-4 Family [Member]
#	5		4
Accruing	0		0
Non-accruing	1,816		1,745
Total	1,816	[1]	1,745	[1]
Residential Mortgage [Member] | Residential Land [Member]
#	2		1
Accruing	257		0
Non-accruing	57		61
Total	314	[1]	61	[1]
Residential Mortgage [Member]
#	7		5
Accruing	257		0
Non-accruing	1,873		1,806
Total	2,130	[1]	1,806	[1]
Commercial Loan [Member] | Commercial Business [Member]
#	2		3
Accruing	683		687
Non-accruing	252		609
Total	935	[1]	1,296	[1]
Commercial Loan [Member] | Commercial Real Estate [Member]
#	21		18
Accruing	1,695		1,713
Non-accruing	4,030		4,543
Total	5,725	[1]	6,256	[1]
Commercial Loan [Member] | Commercial Land [Member]
#	5		5
Accruing	499		499
Non-accruing	1,820		1,852
Total	2,319	[1]	2,351	[1]
Commercial Loan [Member]
#	28		26
Accruing	2,877		2,899
Non-accruing	6,102		7,004
Total	8,979	[1]	9,903	[1]
Consumer Loan [Member] | Home Equity Loans [Member]
#	22		22
Accruing	500		502
Non-accruing	4,254		4,359
Total	4,754	[1]	4,861	[1]
Consumer Loan [Member] | Manufactured Housing [Member]
#	5		1
Accruing	134		135
Non-accruing	94		0
Total	228	[1]	135	[1]
Consumer Loan [Member] | Marine [Member]
#	1		0
Accruing	0		0
Non-accruing	5		0
Total	5	[1]	0	[1]
Consumer Loan [Member]
#	28		23
Accruing	634		637
Non-accruing	4,353		4,359
Total	4,987	[1]	4,996	[1]
Acquired Covered Loans [Member]
#	9		8
Accruing	0		0
Non-accruing	2,410		2,612
Total	$ 2,410	[1]	$ 2,612	[1]

[1] There were no acquired non-covered TDRs in the above noted periods.