Allowance for Loan Losses Details Textual (Details) - Financing Receivable by Loan Portfolio Status [Domain] - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Allowance For Loan And Lease Losses [Line Items]
Financing Receivable, Allowance for Credit Losses, Write-downs	$ 1,600,000		$ 3,800,000
Loan Commitments	6,144,177,000	$ 5,666,483,000	6,144,177,000	$ 5,666,483,000	$ 6,136,313,000
Minimum Non Performing Substandard Loans Outstanding for Allowance for Credit Losses	300,000		300,000
Minimum Non Performing Substandard Doubtful Loans Outstanding for Allowance for Credit Losses	100,000		100,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method	118,000	20,000	236,000	123,000
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	900,000	500,000	1,800,000	1,300,000
Total impaired loans with no related allowance
Allowance For Loan And Lease Losses [Line Items]
Loan Commitments	$ 3,700,000	$ 1,600,000	$ 3,700,000	$ 1,600,000	$ 200,000