Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI (3) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Modifications [Line Items]
Nonaccrual	$ 79,343	$ 65,238
Troubled Debt Restructurings [Member]
Financing Receivable, Modifications [Line Items]
Accruing	1,385	1,320	1,513
Nonaccrual	9,910	13,456	22,760
Total	11,295	14,776	24,273
Troubled Debt Restructurings [Member] | Construction, Land Development and Other Land [Member]
Financing Receivable, Modifications [Line Items]
Accruing	0	0	233
Nonaccrual	3,665	6,247	12,073
Total	3,665	6,247	12,306
Troubled Debt Restructurings [Member] | Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Modifications [Line Items]
Accruing	1,385	1,320	1,280
Nonaccrual	3,733	4,201	5,908
Total	5,118	5,521	7,188
Troubled Debt Restructurings [Member] | Nonfarm, Nonresidential Properties [Member]
Financing Receivable, Modifications [Line Items]
Accruing	0	0	0
Nonaccrual	1,854	2,292	4,582
Total	1,854	2,292	4,582
Troubled Debt Restructurings [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Accruing	0	0	0
Nonaccrual	149	167	197
Total	149	167	197
Troubled Debt Restructurings [Member] | Commercial And Industrial Loans [Member]
Financing Receivable, Modifications [Line Items]
Accruing	0	0
Nonaccrual	509	549
Total	$ 509	$ 549