Employee Benefit Plans (Components Of Pension Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
BancShares Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 3,603	$ 2,785	$ 7,203	$ 6,166
Interest cost	6,750	6,251	13,498	12,807
Expected return on assets	(8,299)	(8,340)	(16,594)	(16,152)
Amortization of prior service cost	52	52	105	105
Amortization of net actuarial loss	2,835	1,546	5,668	3,092
Total pension expense	4,941	$ 2,294	9,880	$ 6,018
Bancorporation Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	932		1,865
Interest cost	1,627		3,255
Expected return on assets	(2,870)		(5,739)
Amortization of prior service cost	0		0
Amortization of net actuarial loss	0		0
Total pension expense	$ (311)		$ (619)