Loans Receivable and Allowance for Loan Losses (Summary of Nonaccrual Loans, by Type) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012 Nonaccrual_Loans	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans	$ 37,213	$ 34,129
Period used to determine when a loan receivable is moved to nonaccrual status	90 days
Loans receivable, equal to greater than 90 days past due	19,019	23,370
Amount available to be advanced on nonaccrual loans	73
Number of nonaccrual loans with funds available for advance	2
Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans	17,133	10,162
Loans receivable, equal to greater than 90 days past due	6,945	3,193
Commercial tax-exempt [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans	0	0
Loans receivable, equal to greater than 90 days past due	0	0
Owner occupied real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans	3,230	2,895
Loans receivable, equal to greater than 90 days past due	3,621	1,901
Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans	6,826	8,511
Loans receivable, equal to greater than 90 days past due	2,897	8,304
Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans	4,571	7,820
Loans receivable, equal to greater than 90 days past due	2,463	6,124
Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans	3,149	2,912
Loans receivable, equal to greater than 90 days past due	1,834	2,905
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual loans	2,304	1,829
Loans receivable, equal to greater than 90 days past due	$ 1,259	$ 943