Employee Benefit Plans (Net Periodic Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	$ 592	$ 533	$ 587
Interest cost on projected benefit obligation	3,545	4,860	4,495
Expected return on assets	(3,869)	(4,874)	(5,572)
Prior service cost	0	0	0
Settlement loss	1,805	0	0
Amortization of net loss (gain)	1,836	2,001	1,804
Net expense	3,909	2,520	1,314
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost — benefits earned during the period	0	3	4
Interest cost on projected benefit obligation	286	347	330
Expected return on assets	0	0	0
Prior service cost	4	4	4
Settlement loss	0	0	0
Amortization of net loss (gain)	11	(40)	(41)
Net expense	$ 301	$ 314	$ 297