Employee Benefit Plans (Schedule of Net Period Benefit Cost and Other Amounts Recognized in Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in funded status recognized in other comprehensive loss, before taxes
Total recognized in OCI, before taxes	$ 605	$ 1,671	$ (2,332)
Supplemental Executive Retirement Plan [Member]
Net period benefit cost
Service cost	464	395	446
Interest cost	460	523	488
Recognized net actuarial loss(2)	623	240	561
Net periodic benefit cost	1,547	1,158	1,495
Changes in funded status recognized in other comprehensive loss, before taxes
Net actuarial loss (gain) arising during period	911	1,524	(1,534)
Amortization of net unrecognized actuarial loss	(623)	(240)	(561)
Total recognized in OCI, before taxes	288	1,284	(2,095)
Total recognized in net periodic benefit cost and OCI, before taxes	1,835	2,442	(600)
Other Postretirement Benefits Plan [Member]
Net period benefit cost
Service cost	28	48	46
Interest cost	123	148	132
Recognized net actuarial loss(2)	78	31	52
Amortization of prior service credit(2)	(24)	(24)	(24)
Net periodic benefit cost	205	203	206
Changes in funded status recognized in other comprehensive loss, before taxes
Net actuarial loss (gain) arising during period	371	394	(209)
Amortization of net unrecognized actuarial loss	(78)	(31)	(52)
Amortization of prior service credit	24	24	24
Total recognized in OCI, before taxes	317	387	(237)
Total recognized in net periodic benefit cost and OCI, before taxes	$ 522	$ 590	$ (31)