Employee Benefit Plans (Components Of Pension Expense) (Details) - BancShares Plan - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 3,457	$ 3,113
Interest cost	8,531	9,291
Expected return on assets	(16,409)	(15,635)
Amortization of prior service cost	0	14
Amortization of net actuarial loss	6,264	2,741
Total pension expense	$ 1,843	$ (476)