Loans Receivable and Credit Quality Impaired Loans With and Without Related Allowance (Details) (USD $)	3 Months Ended				9 Months Ended				12 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011		Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 94,624,000	[1]	$ 86,451,000	[2]	$ 94,624,000	[1]	$ 86,451,000	[2]	$ 89,793,000	[3]
Impaired Financing Receivable, Unpaid Principal Balance	123,179,000		108,027,000		123,179,000		108,027,000		111,492,000
Impaired Financing Receivable, Related Allowance	4,266,000		4,011,000		4,266,000		4,011,000		4,208,000
Impaired Financing Receivable, Average Recorded Investment	90,366,000		96,645,000		91,980,000		112,162,000		106,264,000
Impaired Financing Receivable, Interest Income, Cash Basis Method	431,000		332,000		1,412,000		716,000		1,213,000
Impaired Financing Receivable, with Related Allowance, Recorded Investment	40,017,000	[1]	30,702,000	[2]	40,017,000	[1]	30,702,000	[2]	31,965,000	[3]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	41,446,000		33,781,000		41,446,000		33,781,000		33,198,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	42,396,000		38,632,000		40,570,000		35,026,000		34,023,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	320,000		195,000		843,000		393,000		583,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	54,607,000	[1]	55,749,000	[2]	54,607,000	[1]	55,749,000	[2]	57,828,000	[3]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	81,733,000		74,246,000		81,733,000		74,246,000		78,294,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	47,970,000		58,013,000		51,410,000		77,136,000		72,241,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	111,000		137,000		569,000		323,000		630,000
Charge offs to date on impaired loans receivable	24,200,000		18,700,000		24,200,000		18,700,000		18,200,000
Nonaccrual Interest Payments to Date Applied to Principal	4,400,000		2,900,000		4,400,000		2,900,000		3,500,000
Commercial and industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	6,349,000	[1]	2,535,000	[2]	6,349,000	[1]	2,535,000	[2]	6,718,000	[3]
Impaired Financing Receivable, Unpaid Principal Balance	9,646,000		2,945,000		9,646,000		2,945,000		7,376,000
Impaired Financing Receivable, Related Allowance	123,000		15,000		123,000		15,000		149,000
Impaired Financing Receivable, Average Recorded Investment	6,417,000		2,774,000		6,809,000		7,666,000		7,185,000
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		0		0		16,000		59,000
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,285,000	[1]	121,000	[2]	1,285,000	[1]	121,000	[2]	1,123,000	[3]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,285,000		125,000		1,285,000		125,000		1,137,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	2,731,000		124,000		1,983,000		803,000		748,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0		0		0		0		0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	5,064,000	[1]	2,414,000	[2]	5,064,000	[1]	2,414,000	[2]	5,595,000	[3]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	8,361,000		2,820,000		8,361,000		2,820,000		6,239,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	3,686,000		2,650,000		4,826,000		6,863,000		6,437,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0		0		0		16,000		59,000
Commercial real estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	60,305,000	[1]	62,585,000	[2]	60,305,000	[1]	62,585,000	[2]	58,165,000	[3]
Impaired Financing Receivable, Unpaid Principal Balance	81,935,000		79,794,000		81,935,000		79,794,000		74,088,000
Impaired Financing Receivable, Related Allowance	2,507,000		3,172,000		2,507,000		3,172,000		3,307,000
Impaired Financing Receivable, Average Recorded Investment	53,176,000		73,579,000		55,505,000		81,360,000		76,039,000
Impaired Financing Receivable, Interest Income, Cash Basis Method	239,000		250,000		788,000		536,000		813,000
Impaired Financing Receivable, with Related Allowance, Recorded Investment	25,516,000	[1]	23,811,000	[2]	25,516,000	[1]	23,811,000	[2]	23,202,000	[3]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	26,901,000		26,722,000		26,901,000		26,722,000		24,398,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	24,462,000		32,552,000		25,190,000		27,036,000		26,274,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	200,000		153,000		562,000		274,000		440,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	34,789,000	[1]	38,774,000	[2]	34,789,000	[1]	38,774,000	[2]	34,963,000	[3]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	55,034,000		53,072,000		55,034,000		53,072,000		49,690,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	28,714,000		41,027,000		30,315,000		54,324,000		49,765,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	39,000		97,000		226,000		262,000		373,000
Construction and land [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	5,648,000	[1]	5,580,000	[2]	5,648,000	[1]	5,580,000	[2]	7,772,000	[3]
Impaired Financing Receivable, Unpaid Principal Balance	7,845,000		8,832,000		7,845,000		8,832,000		12,085,000
Impaired Financing Receivable, Related Allowance	425,000		327,000		425,000		327,000		219,000
Impaired Financing Receivable, Average Recorded Investment	7,842,000		6,553,000		7,777,000		9,774,000		9,064,000
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		0		97,000		0		0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,018,000	[1]	1,565,000	[2]	1,018,000	[1]	1,565,000	[2]	1,279,000	[3]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,062,000		1,729,000		1,062,000		1,729,000		1,302,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	2,187,000		1,524,000		1,662,000		2,976,000		2,591,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0		0		0		0		0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	4,630,000	[1]	4,015,000	[2]	4,630,000	[1]	4,015,000	[2]	6,493,000	[3]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	6,783,000		7,103,000		6,783,000		7,103,000		10,783,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	5,655,000		5,029,000		6,115,000		6,798,000		6,473,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0		0		97,000		0		0
Residential [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	21,831,000	[1]	15,294,000	[2]	21,831,000	[1]	15,294,000	[2]	16,681,000	[3]
Impaired Financing Receivable, Unpaid Principal Balance	23,262,000		15,965,000		23,262,000		15,965,000		17,452,000
Impaired Financing Receivable, Related Allowance	1,080,000		366,000		1,080,000		366,000		402,000
Impaired Financing Receivable, Average Recorded Investment	22,367,000		12,488,000		21,351,000		12,331,000		13,089,000
Impaired Financing Receivable, Interest Income, Cash Basis Method	190,000		81,000		520,000		160,000		335,000
Impaired Financing Receivable, with Related Allowance, Recorded Investment	12,067,000	[1]	5,074,000	[2]	12,067,000	[1]	5,074,000	[2]	6,230,000	[3]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	12,067,000		5,074,000		12,067,000		5,074,000		6,230,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	12,885,000		4,301,000		11,604,000		4,080,000		4,279,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	119,000		41,000		277,000		115,000		137,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	9,764,000	[1]	10,220,000	[2]	9,764,000	[1]	10,220,000	[2]	10,451,000	[3]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	11,195,000		10,891,000		11,195,000		10,891,000		11,222,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	9,482,000		8,187,000		9,747,000		8,251,000		8,810,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	71,000		40,000		243,000		45,000		198,000
Home equity [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	491,000	[1]	457,000	[2]	491,000	[1]	457,000	[2]	457,000	[3]
Impaired Financing Receivable, Unpaid Principal Balance	491,000		491,000		491,000		491,000		491,000
Impaired Financing Receivable, Related Allowance	131,000		131,000		131,000		131,000		131,000
Impaired Financing Receivable, Average Recorded Investment	491,000		1,251,000		485,000		1,016,000		876,000
Impaired Financing Receivable, Interest Income, Cash Basis Method	2,000		1,000		7,000		4,000		6,000
Impaired Financing Receivable, with Related Allowance, Recorded Investment	131,000	[1]	131,000	[2]	131,000	[1]	131,000	[2]	131,000	[3]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	131,000		131,000		131,000		131,000		131,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	131,000		131,000		131,000		131,000		131,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	1,000		1,000		4,000		4,000		6,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	360,000	[1]	326,000	[2]	360,000	[1]	326,000	[2]	326,000	[3]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	360,000		360,000		360,000		360,000		360,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	360,000		1,120,000		354,000		885,000		745,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	1,000		0		3,000		0		0
Consumer and other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	0	[1]	0	[2]	0	[1]	0	[2]	0	[3]
Impaired Financing Receivable, Unpaid Principal Balance	0		0		0		0		0
Impaired Financing Receivable, Related Allowance	0		0		0		0		0
Impaired Financing Receivable, Average Recorded Investment	73,000		0		53,000		15,000		11,000
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		0		0		0		0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[1]	0	[2]	0	[1]	0	[2]	0	[3]
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		0		0		0		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0		0		0		0		0
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0		0		0		0		0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	[1]	0	[2]	0	[1]	0	[2]	0	[3]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0		0		0		0		0
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	73,000		0		53,000		15,000		11,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	$ 0		$ 0		$ 0		$ 0		$ 0

[1] (1)Recorded investment represents the client loan balance net of historical charge-offs of $24.2 million and historical nonaccrual interest paid, which was applied to principal, of $4.4 million.

[2] (1)Recorded investment represents the client loan balance net of historical charge-offs of $18.7 million and historical nonaccrual interest paid, which was applied to principal, of $2.9 million.

[3] (1)Recorded investment represents the client loan balance net of historical charge-offs of $18.2 million and historical nonaccrual interest paid, which was applied to principal, of $3.5 million.