Securities (Narrative) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2011 Security	Jun. 30, 2012
Investment Securities [Line Items]
Investment securities pledged as collateral	$ 6,300,000	$ 5,600,000
Percentage of gross unrealized losses on amortized costs of investment securities	2.10%
Government Sponsored Enterprises [Member]
Investment Securities [Line Items]
Number of investment securities	1
Aggregate unrealized loss on investment securities	2,000	23,000
State And Municipal Securities [Member]
Investment Securities [Line Items]
Number of investment securities	1
Aggregate unrealized loss on investment securities
Mortgage-Backed Securities [Member]
Investment Securities [Line Items]
Number of investment securities	27
Aggregate unrealized loss on investment securities	120,000	104,000
Other Securities [Member]
Investment Securities [Line Items]
Number of investment securities	5
Aggregate unrealized loss on investment securities	$ 243,000	$ 118,000