Derivative Instruments And Other Hedging Activities (Narrative) (Detail) (USD $)	6 Months Ended
	Jun. 30, 2012 Day	Dec. 31, 2011	Jun. 30, 2011
Derivatives, Fair Value [Line Items]
Derivative, notional amount	$ 70,000,000	$ 70,000,000	$ 70,000,000
Fair value of derivatives	195,000
Rate lock period (in days)	60
Derivative, collateral, right to reclaim cash	4,460,000		1,210,000
Customers Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative, notional amount	331,303,000		274,688,000
Offsetting Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative, notional amount	331,303,000	293,794,000
Equity-Indexed Certificates Of Deposit Asset [Member]
Derivatives, Fair Value [Line Items]
Derivative, notional amount	177,013,000		123,880,000
Equity-Indexed Certificates Of Deposit Liability [Member]
Derivatives, Fair Value [Line Items]
Derivative, notional amount	$ 177,013,000		$ 158,164,000