Estimated Fair Values (Assets And Liabilities Carried At Fair Value On A Nonrecurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate remeasured during current year	$ 53,988		$ 61,231	$ 68,964		$ 65,559
Other Real Estate, Non Covered	53,840		60,759	68,373		58,742
Other Real Estate, Covered	148		472	591		6,817
Mortgage servicing rights	22,003	$ 20,524	20,415	$ 17,730	$ 16,824	$ 19,351
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	71,068		70,977
Other real estate remeasured during current year	38,533		45,402
Mortgage servicing rights			342
Fair Value, Measurements, Nonrecurring | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0		0
Other real estate remeasured during current year	0		0
Mortgage servicing rights			0
Fair Value, Measurements, Nonrecurring | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0		0
Other real estate remeasured during current year	0		0
Mortgage servicing rights			0
Fair Value, Measurements, Nonrecurring | Significant Unobservable Inputs (Level 3 Inputs)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	71,068		70,977
Other real estate remeasured during current year	$ 38,533		45,402
Mortgage servicing rights			$ 342