Defined Benefit Pension Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Qualified Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	$ 509	$ 561	$ 1,018	$ 1,122
Interest cost	[2]	742	678	1,484	1,357
Expected return on plan assets	[2]	(1,123)	(1,318)	(2,247)	(2,636)
Amortization of prior service (credit) cost	[2]	(4)	(5)	(8)	(11)
Recognized net actuarial loss	[2]	198	374	396	748
Net periodic benefit cost		322	290	643	580
Non-Qualified Retirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	32	27	63	54
Interest cost	[2]	141	118	282	237
Expected return on plan assets	[2]	0	0	0	0
Amortization of prior service (credit) cost	[2]	0	0	0	0
Recognized net actuarial loss	[2]	101	103	203	205
Net periodic benefit cost		$ 274	$ 248	$ 548	$ 496

[1] Included in salaries and employee benefits expense in the Unaudited Consolidated Statements of Income.

[2] Included in other expenses in the Unaudited Consolidated Statements of Income.