Loans Receivable and Allowance for Loan Losses (Summary of Loans Receivable) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Qualifying loans pledged as FHLB collateral	$ 622,400,000
Bank loans receivable, Gross	1,802,245,000	1,750,872,000
Bank loans receivable, Allowance for loan losses	23,934,000	23,110,000	27,472,000	25,282,000
Bank loans receivable, Net	1,778,311,000	1,727,762,000
Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	465,931,000	447,144,000
Bank loans receivable, Allowance for loan losses	7,914,000	8,178,000	10,408,000	9,959,000
Commercial tax-exempt [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	77,566,000	81,734,000
Bank loans receivable, Allowance for loan losses	68,000	72,000	75,000	83,000
Owner occupied real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	306,765,000	302,417,000
Bank loans receivable, Allowance for loan losses	2,236,000	2,180,000	2,208,000	2,129,000
Commercial construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	123,789,000	133,176,000
Bank loans receivable, Allowance for loan losses	5,842,000	5,559,000	7,967,000	7,222,000
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	512,582,000	473,188,000
Bank loans receivable, Allowance for loan losses	4,640,000	4,161,000	5,038,000	3,983,000
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	98,827,000	97,766,000
Bank loans receivable, Allowance for loan losses	1,023,000	960,000	338,000	324,000
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	216,785,000	215,447,000
Bank loans receivable, Allowance for loan losses	$ 1,329,000	$ 1,303,000	$ 787,000	$ 793,000