Benefit Plan (Components Of Net Periodic Benefit Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Other components of net periodic benefit income	$ 1,705	$ 1,448	$ 3,410	$ 2,896
Total other income	23,242	20,699	50,145	39,654
Employee Benefits and Share-based Compensation	7,630	6,206	14,659	12,674
Other expense	1,665	1,749	3,575	3,405
Total other expense	52,534	49,554	106,842	98,464
Service cost	1,637	1,317	3,274	2,634
Interest cost	1,309	1,271	2,618	2,542
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(68)	(131)	(136)	(262)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1,637	1,317	3,274	2,634
Interest cost	1,309	1,271	2,618	2,542
Expected return on plan assets	(3,354)	(2,863)	(6,708)	(5,726)
Amortization of prior service cost	0	0	0	0
Recognized net actuarial loss	340	144	680	288
Benefit expense	(68)	(131)	(136)	(262)
Pension plan contributions	0	0	0	0
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	244	185	478	370
Interest cost	44	161	161	322
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	288	346	639	692
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	244	185	478	370
Interest cost	44	161	161	322
Benefit expense	$ 288	346	$ 639	692
Restatement Adjustment [Member] | Accounting Standards Update 2017-07 [Member]
Defined Benefit Plan Disclosure [Line Items]
Other components of net periodic benefit income		1,448		2,896
Total other income		20,699		39,654
Employee Benefits and Share-based Compensation		6,206		12,674
Other expense		1,749		3,405
Total other expense		49,554		98,464
Previously Reported [Member] | Accounting Standards Update 2017-07 [Member]
Defined Benefit Plan Disclosure [Line Items]
Other components of net periodic benefit income		0		0
Total other income		19,251		36,758
Employee Benefits and Share-based Compensation		4,919		10,100
Other expense		1,588		3,083
Total other expense		$ 48,106		$ 95,568