Loans and Leases (Narrative) (Details) - Internal Credit Assessment [Domain] - Class of Financing Receivable [Domain] - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
PCI loans	$ 1,123,239	$ 1,186,498	$ 1,109,933	$ 1,029,426
Noncovered loans pledged to secure debt obligations	$ 3,310,000	3,160,000
Threshold period past due for write-off of Business credit card loans (days)	120 days
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	$ 2,380,000	2,200,000
Advances from Federal Home Loan Banks	290,300	240,300
Federal Home Loan Bank Advances, Current Borrowing Capacity	2,090,000	1,960,000
Loans and Leases Receivable, Gross, Carrying Amount, Covered	319,700	485,300
PCI Loans
Financing Receivable, Recorded Investment [Line Items]
Nonaccruing	8,672	33,422
PCI loans	1,123,239	1,186,498
Bancorporation
Financing Receivable, Recorded Investment [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Purchase Discount Remaining	49,300	$ 61,200
Sun American Bank
Financing Receivable, Recorded Investment [Line Items]
PCI loans	30,900
First Regional Bank
Financing Receivable, Recorded Investment [Line Items]
PCI loans	9,000
Williamsburg First National Bank
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	$ 8,200