Employee Benefit Plans (Components of Net Periodic Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Service Cost	$ 5,493	$ 4,351	$ 5,153
Interest Cost	1,469	1,340	862
Expected Return on Assets	(1,539)	(1,252)	(973)
Amortization of Prior Service Cost	487	406	0
Total Net Periodic Benefit Costs	$ 5,910	$ 4,845	$ 5,042