Loans and Leases (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	$ 5,500,000	$ 6,080,000
Advances from Federal Home Loan Banks	660,200	510,300
Federal Home Loan Bank Advances, Current Borrowing Capacity	4,840,000	5,570,000
Noncovered loans pledged to secure debt obligations	$ 8,260,000	8,580,000
Charge off of past due business credit card loans (days)	120 days
Loans and Leases Receivable, Gross, Carrying Amount, Covered	$ 84,800	272,600
Carrying Value of Loans Held-for-Investment Sold at a Premium or Discount	77,700	45,900
Gain (Loss) on Sale of Loans and Leases	3,758	0	$ 0
Non-PCI Loans
Financing Receivable, Recorded Investment [Line Items]
Accretion Income	14,300	18,700
PCI Loans
Financing Receivable, Recorded Investment [Line Items]
Nonaccruing	3,451	7,579
Loans on the Cost Recovery Method | PCI Loans
Financing Receivable, Recorded Investment [Line Items]
Carrying value of acquired impaired loans	500	5,300
Cordia Bancorp Inc.
Financing Receivable, Recorded Investment [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Purchase Discount Remaining	4,200
Bancorporation
Financing Receivable, Recorded Investment [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Purchase Discount Remaining	27,400	41,100
Medical and Dental [Member]
Financing Receivable, Recorded Investment [Line Items]
Concentration of Risk, Loan Receivables, Industry	$ 4,660,000	$ 4,280,000
Concentration Risk, Percentage	21.50%	21.20%