Loans and Allowance for Loan Losses (Narrative) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($) contract agreement	Sep. 30, 2016 USD ($) contract	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 269,676			$ 317,970
TDRs both accruing and nonaccruing	216,000			121,700
Post-Modification outstanding recorded investment	$ 147,454	$ 58,447
Number of TDRs subsequently defaulted | contract	0	0
TDRs and loans impaired with minimum aggregate relationship balances	$ 1,000
Loans receivable			$ 154,000
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	$ 119,300			81,900
Troubled Debt Restructurings [Member] | Loans With Extended Amortization Terms Or Other Payment Concessions [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extended terms and other payment concessions	96,100	$ 43,400
Troubled Debt Restructurings [Member] | Loans With Significant Covenant Waivers [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Convenant waivers	50,100	14,700
Troubled Debt Restructurings [Member] | Loans With Other Modifications [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Post-Modification outstanding recorded investment	$ 1,300
Other Modifications		$ 400
FDIC Loss Share Agreement [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loss share agreements | agreement	2
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans	$ 14,063			12,351
Post-Modification outstanding recorded investment	42
Real estate in process of foreclosure	8,000			10,100
Real estate acquired through foreclosure	$ 2,500			$ 3,100