Loans, Allowance for Loan Losses and Credit Quality (Age Analysis of Past Due Financing Receivables) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014 loan	Dec. 31, 2013 loan
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days	117	209
Principal Balance 30-59 Days	$ 14,240	$ 15,925
Number of Loans 60-89 Days	56	60
Principal Balance 60-89 Days	6,433	3,498
Number of Loans 90 Days or More	136	161
Principal Balance 90 Days or More	13,515	21,116
Number of Loans Total Past Due	309	430
Principal Balance Total Past Due	34,188	40,539
Current	4,851,312	4,677,768
Total Financing Receivables	4,885,500	4,718,307
Recorded Investment >90 Days and Accruing	597	525
Commercial and Industrial [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days	8	9
Principal Balance 30-59 Days	1,011	743
Number of Loans 60-89 Days	12	6
Principal Balance 60-89 Days	1,209	327
Number of Loans 90 Days or More	20	20
Principal Balance 90 Days or More	1,481	3,763
Number of Loans Total Past Due	40	35
Principal Balance Total Past Due	3,701	4,833
Current	849,626	779,369
Total Financing Receivables	853,327	784,202
Recorded Investment >90 Days and Accruing
Commercial Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days	16	21
Principal Balance 30-59 Days	9,105	8,643
Number of Loans 60-89 Days	5	2
Principal Balance 60-89 Days	3,218	356
Number of Loans 90 Days or More	20	30
Principal Balance 90 Days or More	3,652	8,155
Number of Loans Total Past Due	41	53
Principal Balance Total Past Due	15,975	17,154
Current	2,284,658	2,232,106
Total Financing Receivables	2,300,633	2,249,260
Recorded Investment >90 Days and Accruing
Commercial Construction [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days		1
Principal Balance 30-59 Days		847
Number of Loans 60-89 Days
Principal Balance 60-89 Days
Number of Loans 90 Days or More		1
Principal Balance 90 Days or More		100
Number of Loans Total Past Due		2
Principal Balance Total Past Due		947
Current	252,222	222,912
Total Financing Receivables	252,222	223,859
Recorded Investment >90 Days and Accruing
Small Business [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days	8	18
Principal Balance 30-59 Days	144	353
Number of Loans 60-89 Days	5	6
Principal Balance 60-89 Days	22	227
Number of Loans 90 Days or More	8	14
Principal Balance 90 Days or More	224	247
Number of Loans Total Past Due	21	38
Principal Balance Total Past Due	390	827
Current	78,565	76,413
Total Financing Receivables	78,955	77,240
Recorded Investment >90 Days and Accruing
Residential Real Estate [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days	15	23
Principal Balance 30-59 Days	1,594	2,903
Number of Loans 60-89 Days	7	8
Principal Balance 60-89 Days	1,468	1,630
Number of Loans 90 Days or More	41	39
Principal Balance 90 Days or More	6,352	6,648
Number of Loans Total Past Due	63	70
Principal Balance Total Past Due	9,414	11,181
Current	532,187	530,262
Total Financing Receivables	541,601	541,443
Recorded Investment >90 Days and Accruing	476	462
Consumer Home Equity [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days	21	27
Principal Balance 30-59 Days	2,185	1,922
Number of Loans 60-89 Days	9	8
Principal Balance 60-89 Days	419	852
Number of Loans 90 Days or More	22	23
Principal Balance 90 Days or More	1,752	2,055
Number of Loans Total Past Due	52	58
Principal Balance Total Past Due	4,356	4,829
Current	836,459	817,312
Total Financing Receivables	840,815	822,141
Recorded Investment >90 Days and Accruing	82
Consumer - Other [Member]
Age Analysis of Past Due Financing Receivables
Number of Loans 30-59 Days	49	110
Principal Balance 30-59 Days	201	514
Number of Loans 60-89 Days	18	30
Principal Balance 60-89 Days	97	106
Number of Loans 90 Days or More	25	34
Principal Balance 90 Days or More	54	148
Number of Loans Total Past Due	92	174
Principal Balance Total Past Due	352	768
Current	17,595	19,394
Total Financing Receivables	17,947	20,162
Recorded Investment >90 Days and Accruing	$ 39	$ 63