Loan Portfolio and Credit Quality Impaired Loans With and Without Related Allowance (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				12 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	$ 42,345	[1]	$ 54,877	[1]	$ 40,666	[1]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	19,345	[1]	42,269	[1]	23,401	[1]
Impaired Financing Receivable, Recorded Investment	61,690	[1]	97,146	[1]	64,067	[1]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	55,505		77,317		55,388
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	20,370		44,156		24,199
Impaired Financing Receivable, Unpaid Principal Balance	75,875		121,473		79,587
Impaired Financing Receivable, Related Allowance	2,151		4,728		1,978
Impaired Financing Receivable, Related Allowance	2,151		4,728		1,978
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	40,533		53,426		43,508
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	22,342		37,648		36,155
Impaired Financing Receivable, Average Recorded Investment	62,875		91,074		79,663
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	417		303		1,845
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	169		228		1,357
Impaired Financing Receivable, Interest Income, Cash Basis Method	586		531		3,202
Commercial and industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,049	[1]	7,859	[1]	2,084	[1]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,082	[1]	3,245	[1]	1,353	[1]
Impaired Financing Receivable, Recorded Investment	3,131	[1]	11,104	[1]	3,437	[1]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	3,161		9,043		3,222
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,191		3,310		1,453
Impaired Financing Receivable, Unpaid Principal Balance	4,352		12,353		4,675
Impaired Financing Receivable, Related Allowance	74		369		100
Impaired Financing Receivable, Related Allowance	74		369		100
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	2,110		7,251		3,908
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,284		1,676		2,228
Impaired Financing Receivable, Average Recorded Investment	3,394		8,927		6,136
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	3		81		332
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	9		4		63
Impaired Financing Receivable, Interest Income, Cash Basis Method	12		85		395
Commercial real estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	29,346	[1]	39,348	[1]	31,917	[1]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	7,814	[1]	24,475	[1]	8,692	[1]
Impaired Financing Receivable, Recorded Investment	37,160	[1]	63,823	[1]	40,609	[1]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	40,065		58,523		42,493
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	8,243		25,957		9,166
Impaired Financing Receivable, Unpaid Principal Balance	48,308		84,480		51,659
Impaired Financing Receivable, Related Allowance	1,095		2,446		730
Impaired Financing Receivable, Related Allowance	1,095		2,446		730
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	30,416		39,835		33,861
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	8,453		20,702		17,904
Impaired Financing Receivable, Average Recorded Investment	38,869		60,537		51,765
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	269		101		1,265
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	91		112		810
Impaired Financing Receivable, Interest Income, Cash Basis Method	360		213		2,075
Construction and land [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	730	[1]	934	[1]	1,072	[1]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,724	[1]	3,965	[1]	2,758	[1]
Impaired Financing Receivable, Recorded Investment	3,454	[1]	4,899	[1]	3,830	[1]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,456		1,547		1,798
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	2,951		4,046		2,982
Impaired Financing Receivable, Unpaid Principal Balance	4,407		5,593		4,780
Impaired Financing Receivable, Related Allowance	239		417		236
Impaired Financing Receivable, Related Allowance	239		417		236
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	816		2,633		1,472
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	2,731		1,637		3,415
Impaired Financing Receivable, Average Recorded Investment	3,547		4,270		4,887
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0		91		109
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0		0		0
Impaired Financing Receivable, Interest Income, Cash Basis Method	0		91		109
Residential [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	10,163	[1]	6,696	[1]	5,536	[1]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	7,725	[1]	10,584	[1]	10,598	[1]
Impaired Financing Receivable, Recorded Investment	17,888	[1]	17,280	[1]	16,134	[1]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	10,766		8,164		7,818
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	7,985		10,843		10,598
Impaired Financing Receivable, Unpaid Principal Balance	18,751		19,007		18,416
Impaired Financing Receivable, Related Allowance	743		1,496		912
Impaired Financing Receivable, Related Allowance	743		1,496		912
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	7,134		3,427		4,139
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	9,874		13,633		12,608
Impaired Financing Receivable, Average Recorded Investment	17,008		17,060		16,747
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	144		29		134
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	69		112		484
Impaired Financing Receivable, Interest Income, Cash Basis Method	213		141		618
Home equity [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	50	[1]	40	[1]	50	[1]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[1]	0	[1]	0	[1]
Impaired Financing Receivable, Recorded Investment	50	[1]	40	[1]	50	[1]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	50		40		50
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		0		0
Impaired Financing Receivable, Unpaid Principal Balance	50		40		50
Impaired Financing Receivable, Related Allowance	0		0		0
Impaired Financing Receivable, Related Allowance	0		0		0
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	50		280		126
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0		0		0
Impaired Financing Receivable, Average Recorded Investment	50		280		126
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	1		1		5
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0		0		0
Impaired Financing Receivable, Interest Income, Cash Basis Method	1		1		5
Consumer and other [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	7	[1]	0	[1]	7	[1]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	[1]	0	[1]	0	[1]
Impaired Financing Receivable, Recorded Investment	7	[1]	0	[1]	7	[1]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	7		0		7
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0		0		0
Impaired Financing Receivable, Unpaid Principal Balance	7		0		7
Impaired Financing Receivable, Related Allowance	0		0		0
Impaired Financing Receivable, Related Allowance	0		0		0
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	7		0		2
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0		0		0
Impaired Financing Receivable, Average Recorded Investment	7		0		2
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	0		0		0
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method	0		0		0
Impaired Financing Receivable, Interest Income, Cash Basis Method	$ 0		$ 0		$ 0

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