Employee Benefit Plans (Schedule of Changes in Accumulated Postretirement Benefits Obligations) (Details) - Postretirement Medical and Life Benefit Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Obligation at the Beginning of Year	$ 1,154	$ 1,061
Unrecognized Loss (Gain)	296	74
Components of Net Periodic Postretirement Benefit Cost
Service Cost	83	69	$ 50
Interest Cost	43	34	29
Net Expected Benefit Payments	(92)	(84)
Amendments	14
Obligation at End of Year	$ 1,498	$ 1,154	$ 1,061