Loans and Credit Quality (Average Recorded Investment And Interest Income Recognized On Impaired Loans) (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	[1]	$ 91,619	$ 115,188	$ 90,220	$ 113,902
Interest Income Recognized	[1]	350	460	559	890
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	[1]	59,380	55,534	55,791	48,935
Interest Income Recognized	[1]	316	419	500	801
Commercial real estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	[1]	14,823	36,960	16,359	41,617
Interest Income Recognized	[1]	10	20	13	44
Residential real estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	[1]	4,454	9,481	4,676	9,700
Interest Income Recognized	[1]	0	0	0	0
Home equity [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	[1]	12,714	12,614	13,094	13,018
Interest Income Recognized	[1]	24	21	46	45
Personal [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	[1]	248	599	300	632
Interest Income Recognized	[1]	$ 0	$ 0	$ 0	$ 0

[1] Represents amounts while classified as impaired for the periods presented.