Loans and Other Repossessed Assets Acquired (Detail) - Summary of the loans that were restructured as TDRs (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Dec. 31, 2012
#	63		54
Rate	$ 4,686	[1]	$ 4,425	[1]
Structure	11,410	[1]	12,280	[1]
Increase to Allowance	237		269
Residential Loans [Member]
#	7		5
Rate	596	[1]	604	[1]
Structure	1,534	[1]	1,202	[1]
Increase to Allowance	0		0
Residential 1-4 Family [Member]
#	5		4
Rate	539	[1]	543	[1]
Structure	1,277	[1]	1,202	[1]
Increase to Allowance	0		0
Residential Land [Member]
#	2		1
Rate	57	[1]	61	[1]
Structure	257	[1]	0	[1]
Increase to Allowance	0		0
Commercial Loan [Member]
#	28		26
Rate	359	[1]	0	[1]
Structure	8,620	[1]	9,903	[1]
Increase to Allowance	230		269
Commercial Business [Member]
#	2		3
Rate	0	[1]	0	[1]
Structure	935	[1]	1,296	[1]
Increase to Allowance	0		0
Commercial Real Estate [Member]
#	21		18
Rate	359	[1]	0	[1]
Structure	5,366	[1]	6,256	[1]
Increase to Allowance	0		12
Commercial Land [Member]
#	5		5
Rate	0	[1]	0	[1]
Structure	2,319	[1]	2,351	[1]
Increase to Allowance	230		257
Consumer Loan [Member] | Home Equity Loans [Member]
#	22		22
Rate	3,597	[1]	3,686	[1]
Structure	1,157	[1]	1,175	[1]
Increase to Allowance	0		0
Consumer Loan [Member] | Manufactured Housing [Member]
#	5		1
Rate	134	[1]	135	[1]
Structure	94	[1]	0	[1]
Increase to Allowance	7		0
Consumer Loan [Member] | Marine [Member]
#	1		0
Rate	0	[1]	0	[1]
Structure	5	[1]	0	[1]
Increase to Allowance	0		0
Consumer Loan [Member]
#	28		23
Rate	3,731	[1]	3,821	[1]
Structure	1,256	[1]	1,175	[1]
Increase to Allowance	7		0
Acquired Covered Loans [Member]
#	9		8
Rate	39	[1]	0	[1]
Structure	2,371	[1]	2,612	[1]
Increase to Allowance	$ 0		$ 0

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