Defined Benefit Pension Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Qualified Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	$ 510	$ 561	$ 1,528	$ 1,683
Interest cost	[2]	741	679	2,225	2,036
Expected return on plan assets	[2]	(1,124)	(1,318)	(3,371)	(3,954)
Amortization of prior service (credit) cost	[2]	(4)	(6)	(12)	(17)
Recognized net actuarial loss	[2]	198	374	594	1,122
Net periodic benefit cost		321	290	964	870
Non-Qualified Retirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	31	27	94	81
Interest cost	[2]	140	119	422	356
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]	104	103	307	308
Net periodic benefit cost		$ 275	$ 249	$ 823	$ 745

[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.