Loans and Allowance for Loan Losses (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) contract agreement	Mar. 31, 2015 contract	Dec. 31, 2015 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carryover of related allowance for loan losses	$ 0
Number of loss share agreements | agreement	2
Nonaccrual loans	$ 237,303		$ 159,713
TDRs both accruing and nonaccruing	$ 63,900		13,100
Number of TDRs subsequently defaulted | contract	0	0
TDRs and loans impaired with minimum aggregate relationship balances	$ 1,000
Real estate acquired through foreclosure	$ 23,191		26,256
Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Period for which payments of principal and interest are past due	less than 90 days
Troubled Debt Restructurings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 18,300		8,800
Originated Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 234,395		$ 156,721
FDIC Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans
Commercial Non-Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 165,930		$ 88,743
Commercial Non-Real Estate [Member] | Originated Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 165,930		$ 88,743
Commercial Non-Real Estate [Member] | FDIC Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 22,125		$ 20,816
Commercial Real Estate [Member] | Originated Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 19,217		$ 17,824
Commercial Real Estate [Member] | FDIC Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 8,538		$ 9,061
Mortgage loan in process of foreclosure	6,000		7,400
Real estate acquired through foreclosure	5,900		9,300
Consumer [Member] | Originated Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 8,538		$ 9,061
Consumer [Member] | FDIC Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans
Mortgage loan in process of foreclosure	$ 4,000		$ 4,100
Real estate acquired through foreclosure	$ 1,100		$ 1,600