Premises And Equipment (Gross Carrying Amounts and Accumulated Amortization of Intangible Assets and Goodwill) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill and Intangible Assets [Line Items]
Net Carrying Amount	$ 510,000	$ 1,330,000
Weighted average useful life	15 years
Goodwill gross	84,171,000	84,171,000
Goodwill	84,171,000	84,171,000	84,808,000
Amortization of Intangible Assets
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	18,339,000	18,339,000
Accumulated Amortization	(17,829,000)	(17,009,000)
Net Carrying Amount	510,000	1,330,000
Amortization of Intangible Assets | Core Deposits
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	9,716,000	9,716,000
Accumulated Amortization	(9,716,000)	(9,352,000)
Net Carrying Amount	0	364,000
Weighted average useful life	0 years	3 months 18 days
Amortization of Intangible Assets | Other Intangible Assets
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	8,623,000	8,623,000
Accumulated Amortization	(8,113,000)	(7,657,000)
Net Carrying Amount	$ 510,000	$ 966,000
Weighted average useful life	1 year 7 months 12 days	2 years 4 months 24 days