Loan Modifications for Corporation's Loans Receivable (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2012 Contract	Jun. 30, 2012 Contract
Financing Receivable, Modifications [Line Items]
Number of New Contracts	3	11
Pre Modification Outstanding Recorded Investment	$ 292	$ 1,264
Post Modification Outstanding Recorded Investment	282	1,254
Number of New Contracts	1	1
Post Modification Outstanding Recorded Investment	175	175
Defaulted Recorded Investment	165	165
Commercial Non Real Estate
Financing Receivable, Modifications [Line Items]
Number of New Contracts		3
Pre Modification Outstanding Recorded Investment		238
Post Modification Outstanding Recorded Investment		238
Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Number of New Contracts	1	1
Pre Modification Outstanding Recorded Investment	175	268
Post Modification Outstanding Recorded Investment	165	258
Number of New Contracts	1	1
Post Modification Outstanding Recorded Investment	175	175
Defaulted Recorded Investment	165	165
Other Consumer
Financing Receivable, Modifications [Line Items]
Number of New Contracts	2	6
Pre Modification Outstanding Recorded Investment	117	757
Post Modification Outstanding Recorded Investment	117	757
Residential 1-4 family
Financing Receivable, Modifications [Line Items]
Number of New Contracts		1
Pre Modification Outstanding Recorded Investment		1
Post Modification Outstanding Recorded Investment		$ 1