Investment Securities (Schedule of Investment Securities' Gross Unrealized Losses and Fair Value By Investment Category) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 16,990	$ 96,381
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	188	2,308
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	125	10,373
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	1	341
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	17,115	106,754
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	189	2,649
Collateralized Mortgage Obligation ("CMO") [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	10,694	78,955
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	131	2,194
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		9,933
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses		333
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	10,694	88,888
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	131	2,527
Federal National Mortgage Association ("FNMA") [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	4,288	6,959
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	54	44
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4,288	6,959
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	54	44
Federal Home Loan Mortgage Corporation ("FHLMC") [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses
Government National Mortgage Association ("GNMA") [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		5,420
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses		57
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		5,420
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		57
U.S. Government And Government Sponsored Enterprises ("GSE") [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	2,008	5,047
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	3	13
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,008	5,047
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	3	13
States And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	125	440
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	1	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	125	440
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	$ 1	$ 8