Loans Receivable and Allowance for Loan Losses (Credit Quality Indicators for Commercial Loans, by Loan Type) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	$ 1,486,633	$ 1,437,659
Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	465,931	447,144
Commercial tax-exempt [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	77,566	81,734
Owner occupied real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	306,765	302,417
Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	123,789	133,176
Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	512,582	473,188
Pass Rated Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	1,416,003	1,362,775
Pass Rated Loans [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	435,605	410,530
Pass Rated Loans [Member] | Commercial tax-exempt [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	77,566	81,734
Pass Rated Loans [Member] | Owner occupied real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	288,510	285,416
Pass Rated Loans [Member] | Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	110,495	120,687
Pass Rated Loans [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	503,827	464,408
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	10,311	12,006
Special Mention [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	5,187	8,064
Special Mention [Member] | Commercial tax-exempt [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	0	0
Special Mention [Member] | Owner occupied real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	3,632	3,624
Special Mention [Member] | Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	285	0
Special Mention [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	1,207	318
Substandard Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	28,523	32,531
Substandard Accrual [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	16,125	18,333
Substandard Accrual [Member] | Commercial tax-exempt [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	0	0
Substandard Accrual [Member] | Owner occupied real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	8,618	8,539
Substandard Accrual [Member] | Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	2,275	3,902
Substandard Accrual [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	1,505	1,757
Substandard Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	31,796	30,347
Substandard Nonaccrual [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	9,014	10,217
Substandard Nonaccrual [Member] | Commercial tax-exempt [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	0	0
Substandard Nonaccrual [Member] | Owner occupied real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	6,005	4,838
Substandard Nonaccrual [Member] | Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	10,734	8,587
Substandard Nonaccrual [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	$ 6,043	$ 6,705