Benefit Plan (Components Of Net Periodic Benefit Expense) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Other components of net periodic benefit income	$ 1,705	$ 1,448
Total other income	26,903	18,955
Employee Benefits and Share-based Compensation	7,029	6,468
Other expense	1,910	1,656
Total other expense	54,308	48,910
Service cost	1,637	1,317
Interest cost	1,309	1,271
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(68)	(131)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1,637	1,317
Interest cost	1,309	1,271
Expected return on plan assets	(3,354)	(2,863)
Amortization of prior service cost	0	0
Recognized net actuarial loss	340	144
Benefit expense	(68)	(131)
Pension plan contributions	0	0
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	185	233
Interest cost	161	117
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	346	350
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	185	233
Interest cost	161	117
Benefit expense	$ 346	350
Restatement Adjustment [Member] | AccountingStandardsUpdate201707 [Member]
Defined Benefit Plan Disclosure [Line Items]
Other components of net periodic benefit income		1,448
Total other income		18,955
Employee Benefits and Share-based Compensation		6,468
Other expense		1,656
Total other expense		48,910
Scenario, Previously Reported [Member] | AccountingStandardsUpdate201707 [Member]
Defined Benefit Plan Disclosure [Line Items]
Other components of net periodic benefit income		0
Total other income		17,507
Employee Benefits and Share-based Compensation		5,181
Other expense		1,495
Total other expense		$ 47,462