Loans Receivable and Allowance for Loan Losses (Summary of Loans Receivable) (Details) (USD $)	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Qualifying loans pledged as FHLB collateral	$ 689,700,000
Bank loans receivable, Gross	1,851,815,000		1,750,872,000
Bank loans receivable, Allowance for loan losses	24,271,000	23,934,000	23,110,000	28,038,000	27,472,000	25,282,000
Bank loans receivable, Net	1,827,544,000		1,727,762,000
Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	467,587,000		447,144,000
Bank loans receivable, Allowance for loan losses	7,100,000	7,914,000	8,178,000	10,549,000	10,408,000	9,959,000
Commercial tax-exempt [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	76,674,000		81,734,000
Bank loans receivable, Allowance for loan losses	67,000	68,000	72,000	74,000	75,000	83,000
Owner occupied real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	308,708,000		302,417,000
Bank loans receivable, Allowance for loan losses	2,233,000	2,236,000	2,180,000	2,207,000	2,208,000	2,129,000
Commercial construction and land development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	130,449,000		133,176,000
Bank loans receivable, Allowance for loan losses	6,696,000	5,842,000	5,559,000	7,810,000	7,967,000	7,222,000
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	544,544,000		473,188,000
Bank loans receivable, Allowance for loan losses	4,840,000	4,640,000	4,161,000	5,059,000	5,038,000	3,983,000
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	103,564,000		97,766,000
Bank loans receivable, Allowance for loan losses	1,061,000	1,023,000	960,000	863,000	338,000	324,000
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans receivable, Gross	220,289,000		215,447,000
Bank loans receivable, Allowance for loan losses	$ 1,333,000	$ 1,329,000	$ 1,303,000	$ 1,258,000	$ 787,000	$ 793,000