Defined Benefit Pension Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Qualified Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	$ 509	$ 561
Interest cost	[2]	742	679
Expected return on plan assets	[2]	(1,124)	(1,318)
Amortization of prior service (credit) cost	[2]	(4)	(6)
Recognized net actuarial loss	[2]	198	374
Net periodic benefit cost		321	290
Non-Qualified Retirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	31	27
Interest cost	[2]	141	119
Expected return on plan assets	[2]	0	0
Amortization of prior service (credit) cost	[2]	0	0
Recognized net actuarial loss	[2]	102	102
Net periodic benefit cost		$ 274	$ 248

[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.