Loans (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross, Commercial	$ 9,220,049		$ 9,116,184	$ 9,220,049	$ 9,116,184	$ 9,128,591
Time period for non-payment of loans that are placed on non-accrual status	90 days
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	$ 5,400		6,100	5,400	6,100	5,400
Days past due for nonaccrual status credit card loans	120 days
Acquired Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net reclassifications from nonaccretable to accretable	$ 8,217	$ 21,212	10,499		30,013
Covered impaired loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	351,100		637,600	351,100	637,600
Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross, Commercial	877,598		1,457,903	877,598	1,457,903	$ 1,086,899
Covered impaired loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net reclassifications from nonaccretable to accretable	2,136		5,549	2,080	11,606
Impaired loans | Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance	$ 504,700		$ 714,200	$ 504,700	$ 714,200