Allowance for Probable Loan Losses (Non-accrual Basis By Loan Class) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Loan loss allowances, financing receivable past due
Non-accrual loans, total	$ 35,067	$ 47,685
Commercial
Loan loss allowances, financing receivable past due
Non-accrual loans, total	21,886	30,894
Commercial Real Estate: Other Construction and Land Development
Loan loss allowances, financing receivable past due
Non-accrual loans, total	3,017	3,668
Commercial Real Estate: Farmland & Commercial
Loan loss allowances, financing receivable past due
Non-accrual loans, total	8,235	11,543
Commercial Real Estate: Multifamily
Loan loss allowances, financing receivable past due
Non-accrual loans, total	571	777
Residential First Lien
Loan loss allowances, financing receivable past due
Non-accrual loans, total	792	383
Residential Junior Lien
Loan loss allowances, financing receivable past due
Non-accrual loans, total	178	21
Consumer
Loan loss allowances, financing receivable past due
Non-accrual loans, total	2	34
Foreign
Loan loss allowances, financing receivable past due
Non-accrual loans, total	$ 386	$ 365