Loans Receivable and Allowance for Loan Losses (Credit Quality Indicators for Commercial Loans, by Loan Type) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	$ 1,582,941	$ 1,437,659
Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	478,605	447,144
Commercial tax-exempt [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	75,986	81,734
Owner occupied real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	312,032	302,417
Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	122,314	133,176
Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	594,004	473,188
Pass Rated Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	1,508,546	1,362,775
Pass Rated Loans [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	436,885	410,530
Pass Rated Loans [Member] | Commercial tax-exempt [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	75,986	81,734
Pass Rated Loans [Member] | Owner occupied real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	293,622	285,416
Pass Rated Loans [Member] | Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	117,308	120,687
Pass Rated Loans [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	584,745	464,408
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	17,943	12,006
Special Mention [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	14,475	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	2,407	3,624
Special Mention [Member] | Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	0	0
Special Mention [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	1,061	318
Substandard Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	31,863	32,531
Substandard Accrual [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	19,271	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	9,049	8,539
Substandard Accrual [Member] | Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	1,752	3,902
Substandard Accrual [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	1,791	1,757
Substandard Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	24,589	30,347
Substandard Nonaccrual [Member] | Commercial and industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	7,974	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	6,954	4,838
Substandard Nonaccrual [Member] | Commercial construction and land development [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	3,254	8,587
Substandard Nonaccrual [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Credit exposure for commercial loans	$ 6,407	$ 6,705