Allowance for Probable Loan Losses (Non-accrual Basis By Loan Class) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Loan loss allowances, financing receivable past due
Non-accrual loans, total	$ 30,862	$ 47,685
Commercial
Loan loss allowances, financing receivable past due
Non-accrual loans, total	14,808	30,894
Commercial Real Estate: Other Construction and Land Development
Loan loss allowances, financing receivable past due
Non-accrual loans, total	3,413	3,668
Commercial Real Estate: Farmland & Commercial
Loan loss allowances, financing receivable past due
Non-accrual loans, total	11,383	11,543
Commercial Real Estate: Multifamily
Loan loss allowances, financing receivable past due
Non-accrual loans, total	164	777
Residential First Lien
Loan loss allowances, financing receivable past due
Non-accrual loans, total	649	383
Residential Junior Lien
Loan loss allowances, financing receivable past due
Non-accrual loans, total	44	21
Consumer
Loan loss allowances, financing receivable past due
Non-accrual loans, total	36	34
Foreign
Loan loss allowances, financing receivable past due
Non-accrual loans, total	$ 365	$ 365