Credit Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Credit Loss [Abstract]
Allowance for Doubtful Accounts Receivable	$ 40,474	$ 29,381	$ 28,469	$ 34,479
Additional Allowance for Credit Losses	2,706	0	0
Provision for Other Credit Losses	11,171	5,933	3,875
Accounts Receivable, Allowance for Credit Loss, Writeoff	(3,863)	(3,464)	(9,326)
Accounts Receivable, Other, Including Dispositions and Foreign Currency	1,079	(1,557)	$ (559)
Retained earnings	$ 8,608,284	$ 8,211,257