Investment Securities (Gross Unrealized Losses And Fair Values By Investment And Length Of Time Of Securities) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	$ 105,524	$ 154,085
Unrealized Losses, Less than 12 Months	1,215	4,160
Fair Value, 12 Months or More	30,594	94,625
Unrealized Losses, 12 Months or More	19,959	22,154
Fair Value, Total	136,118	248,710
Unrealized Losses, Total	21,174	26,314
U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	0	0
Unrealized Losses, Less than 12 Months	0	0
Fair Value, 12 Months or More	0	6,500
Unrealized Losses, 12 Months or More	0	1
Fair Value, Total	0	6,500
Unrealized Losses, Total	0	1
Obligations Of States And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	51,330	0
Unrealized Losses, Less than 12 Months	518	0
Fair Value, 12 Months or More	0	925
Unrealized Losses, 12 Months or More	0	75
Fair Value, Total	51,330	925
Unrealized Losses, Total	518	75
Agency Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	52,391	126,645
Unrealized Losses, Less than 12 Months	178	608
Fair Value, 12 Months or More	0	0
Unrealized Losses, 12 Months or More	0	0
Fair Value, Total	52,391	126,645
Unrealized Losses, Total	178	608
Non-Agency Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	0	6,187
Unrealized Losses, Less than 12 Months	0	563
Fair Value, 12 Months or More	15,110	62,884
Unrealized Losses, 12 Months or More	2,535	9,591
Fair Value, Total	15,110	69,071
Unrealized Losses, Total	2,535	10,154
Other Structured Financial Products [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	0	0
Unrealized Losses, Less than 12 Months	0	0
Fair Value, 12 Months or More	8,393	13,293
Unrealized Losses, 12 Months or More	16,577	11,538
Fair Value, Total	8,393	13,293
Unrealized Losses, Total	16,577	11,538
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	0	21,237
Unrealized Losses, Less than 12 Months	0	2,988
Fair Value, 12 Months or More	6,306	10,102
Unrealized Losses, 12 Months or More	664	723
Fair Value, Total	6,306	31,339
Unrealized Losses, Total	664	3,711
Other Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	1,803	16
Unrealized Losses, Less than 12 Months	519	1
Fair Value, 12 Months or More	785	921
Unrealized Losses, 12 Months or More	183	226
Fair Value, Total	2,588	937
Unrealized Losses, Total	$ 702	$ 227