Allowance for Loan Losses (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Minimum Non Performing Substandard Loans Outstanding for Allowance for Credit Losses	$ 300,000
Minimum Non Performing Substandard Doubtful Loans Outstanding for Allowance for Credit Losses	100,000
Financing Receivable, Allowance for Credit Losses, Write-downs	14,700,000	6,800,000
Impaired Financing Receivable, Interest Income, Cash Basis Method	900,000	1,300,000
Loans and Leases Receivable, Impaired, Troubled Debt, Interest Income	2,800,000	5,500,000	3,200,000
Loan Commitments	6,136,313,000	5,546,635,000
Total impaired loans with no related allowance
Financing Receivable, Allowance for Credit Losses [Line Items]
Loan Commitments	200,000
Acquired Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Allowance for Credit Losses	7,457,000	741,000	0
Covered Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan Losses Before Benefit Attributable to FDIC Loss Share Agreements	10,568,000	23,892,000	35,450,000
Benefit Attributable to FDIC Loss Share Agreements	(2,920,000)	10,790,000	14,728,000
Provision for Loan Lease and Other Losses Covered	$ 7,648,000	$ 13,102,000	$ 20,722,000