Loans and Leases (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Purchase Discount Remaining	$ 41,100	$ 61,200
Loans and Leases Receivable, Collateral for Secured Borrowings	6,080,000	2,200,000
Advances from Federal Home Loan Banks	510,300	240,300
Federal Home Loan Bank Advances, Current Borrowing Capacity	5,570,000	1,960,000
Sale of Loans Held-for-investment	45,900
Noncovered loans pledged to secure debt obligations	$ 8,580,000	3,160,000
Charge off of past due business credit card loans (days)	120 days
Loans and Leases Receivable, Gross, Carrying Amount, Covered	$ 272,600	485,300
Non-PCI Loans
Financing Receivable, Recorded Investment [Line Items]
Accretion Income	18,700	5,900
United Western Bank [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	119,600
First Regional Bank
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	9,700
Colorado Capital Bank [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered	4,800
PCI Loans
Financing Receivable, Recorded Investment [Line Items]
Nonaccruing	7,579	33,422
Loans on the Cost Recovery Method | PCI Loans
Financing Receivable, Recorded Investment [Line Items]
Carrying value of acquired impaired loans	5,300	$ 33,400
Williamsburg First National Bank
Financing Receivable, Recorded Investment [Line Items]
Loans, not covered by FDIC loss share agreements	6,800
Sun American Bank
Financing Receivable, Recorded Investment [Line Items]
Loans, not covered by FDIC loss share agreements	$ 26,700