Loans Receivable and Allowance for Loan Losses (Age Analysis of Past Due Loan Receivables) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Current	$ 2,052,489	$ 1,963,906
Past Due	45,215	34,628
Total loans receivable	2,097,704	1,998,534
Recorded Investment in Loans 90 Days and Greater and Still Accruing	0	445
Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	595,694	514,428
Past Due	11,390	10,699
Total loans receivable	607,084	525,127
Recorded Investment in Loans 90 Days and Greater and Still Accruing	0	0
Commercial tax-exempt [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	58,999	71,151
Past Due	0	0
Total loans receivable	58,999	71,151
Recorded Investment in Loans 90 Days and Greater and Still Accruing	0	0
Owner occupied real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	304,978	325,681
Past Due	10,577	6,389
Total loans receivable	315,555	332,070
Recorded Investment in Loans 90 Days and Greater and Still Accruing	0	445
Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	133,987	137,263
Past Due	6,148	801
Total loans receivable	140,135	138,064
Recorded Investment in Loans 90 Days and Greater and Still Accruing	0	0
Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	630,455	591,383
Past Due	8,680	2,893
Total loans receivable	639,135	594,276
Recorded Investment in Loans 90 Days and Greater and Still Accruing	0	0
Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	114,986	101,233
Past Due	4,097	9,718
Total loans receivable	119,083	110,951
Recorded Investment in Loans 90 Days and Greater and Still Accruing	0	0
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	213,390	222,767
Past Due	4,323	4,128
Total loans receivable	217,713	226,895
Recorded Investment in Loans 90 Days and Greater and Still Accruing	0	0
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	13,592	11,612
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	547	1,574
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial tax-exempt [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Owner occupied real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	2,238	606
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	6,118	611
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	1,626	1,104
Financing Receivables, 30 to 59 Days Past Due [Member] | Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	474	5,067
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	2,589	2,650
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	4,150	6,144
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	171	3,398
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial tax-exempt [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Owner occupied real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	737	44
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	0	190
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	1,390	175
Financing Receivables, 60 to 89 Days Past Due [Member] | Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	831	1,900
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	1,021	437
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	27,473	16,872
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	10,672	5,727
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial tax-exempt [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Owner occupied real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	7,602	5,739
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	30	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	5,664	1,614
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	2,792	2,751
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Past Due	$ 713	$ 1,041