Loans Receivable and Allowance for Loan Losses (Age Analysis of Past Due Loan Receivables) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Current	$ 1,661,929		$ 1,487,781
30-59 Days Past Due	11,526		16,383
60-89 Days Past Due	9,831		9,667
90 Days Past Due and Greater	19,390		14,966
Total Past Due	40,747		41,016
Total loans receivable	1,702,676		1,528,797
Recorded Investment in Loans 90 Days and Greater and Still Accruing	119		220
Transfer of loans to foreclosed assets	2,732	1,989
Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	427,524		368,769
30-59 Days Past Due	2,105		1,096
60-89 Days Past Due	945		3,256
90 Days Past Due and Greater	4,934		3,867
Total Past Due	7,984		8,219
Total loans receivable	435,508		376,988
Recorded Investment in Loans 90 Days and Greater and Still Accruing	0		30
Commercial tax-exempt [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	82,507		92,202
30-59 Days Past Due	0		0
60-89 Days Past Due	0		0
90 Days Past Due and Greater	0		0
Total Past Due	0		0
Total loans receivable	82,507		92,202
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	293,443		265,817
30-59 Days Past Due	2,870		610
60-89 Days Past Due	839		353
90 Days Past Due and Greater	3,403		1,592
Total Past Due	7,112		2,555
Total loans receivable	300,555		268,372
Recorded Investment in Loans 90 Days and Greater and Still Accruing	0		0
Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	116,133		89,250
30-59 Days Past Due	169		4,251
60-89 Days Past Due	0		4,318
90 Days Past Due and Greater	8,074		2,580
Total Past Due	8,243		11,149
Total loans receivable	124,376		100,399
Recorded Investment in Loans 90 Days and Greater and Still Accruing	0		188
Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	439,855		386,821
30-59 Days Past Due	3,937		3,846
60-89 Days Past Due	6,241		78
90 Days Past Due and Greater	578		3,659
Total Past Due	10,756		7,583
Total loans receivable	450,611		394,404
Recorded Investment in Loans 90 Days and Greater and Still Accruing	0		0
Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	90,874		76,587
30-59 Days Past Due	570		4,303
60-89 Days Past Due	1,243		1,252
90 Days Past Due and Greater	1,540		1,757
Total Past Due	3,353		7,312
Total loans receivable	94,227		83,899
Recorded Investment in Loans 90 Days and Greater and Still Accruing	119		0
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	211,593		208,335
30-59 Days Past Due	1,875		2,277
60-89 Days Past Due	563		410
90 Days Past Due and Greater	861		1,511
Total Past Due	3,299		4,198
Total loans receivable	214,892		212,533
Recorded Investment in Loans 90 Days and Greater and Still Accruing	0		2
Improvement to Current Status [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	13,200
Paid Off During the Quarter [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	3,500
Current at Previous Fiscal Year End [Member]
Financing Receivable, Recorded Investment [Line Items]
30-59 Days Past Due	10,800
60-89 Days Past Due	7,700
90 Days Past Due and Greater	4,200
Total Past Due	22,700
Charged Off [Member]
Financing Receivable, Recorded Investment [Line Items]
Write-off of financing receivable	3,200
Transition to Foreclosed Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Transfer of loans to foreclosed assets	$ 2,700